Phosphorus Sustainability Perspectives from Phosphates 2022

By Jacob L. Jones of North Carolina State University

Jacob Jones

The CRU Phosphates 2022 Conference & Exhibition was held in Tampa, Florida, from March 7-9, 2022. This was the first CRU Phosphates meeting held with an in-person component since 2019 and there were 250 attendees in-person and another 65 attending virtually.

As the Director of a recently announced research center on phosphorus sustainability, the Science and Technologies for Phosphorus Sustainability (STEPS) Center, my in-person attendance at the Tampa meeting was an important opportunity to network more closely with important stakeholders in the phosphates sector. As I expected, attending in-person did provide many more additional opportunities than available in the strictly online format during the pandemic, notably the networking lunches and social activities. In fact, I was able to meet many of the individuals whom I reference below.

Sustainability was an important topic in the 2022 meeting. Sustainability is often defined as satisfying the needs of the present without compromising the ability of future generations to satisfy theirs. These present and future needs refer to social and environmental factors (e.g., health, nutrition, equity, accessibility) as well as the economic factors (e.g., economic growth and enabling populations above minimum standards of living).

In the weeks preceding the meeting, the Ukraine-Russia war introduced a new need to think about sustainability of phosphates in the immediate term. While supply chain disruption had affected many industries during the pandemic years, the war in the Ukraine and the extraordinary economic sanctions against Russia introduced unprecedented uncertainty in global phosphate flows.

In the opening markets presentation, “Global phosphate market outlook: Overview, major issues, and the future,” Glen Kurokawa was the first to introduce this uncertainty by saying, “supply chain risks with Russia-Ukraine is the big unknown.” Kurokawa further reinforced how this big unknown is seen atop a myriad of newsworthy factors including the global pandemic, China export restrictions, and the U.S. countervailing duty on certain phosphate imports. Kurokawa’s analysis projects that global phosphate demand will continue to grow by 1-2% per year, although disproportionately throughout the world: A significant rise in demand is expected in Brazil as their agricultural exports grow, demand will decrease in China due to overapplication decreases, and U.S. demand will grow slow and steady. Kurokawa and others throughout the day mentioned the growth of the lithium iron phosphate (LFP) battery market, though LFP batteries are still a small portion of the specialty phosphates market.

A panel discussion later in the day provided opportunities to elaborate on the Russia-Ukraine war and its impacts on global P flows. The panel discussion included a presentation by Chris Lawson, Head of Fertilizers at CRU, and joining the questions and answers were Glen Kurokawa and Willis Thomas, Senior Consultant at CRU. In the opening remarks, it was noted that ammonia, urea, ammonium nitrate (AN), and urea ammonium nitrate (UAN) pose the highest risks, although MOP (potassium chloride) and phosphate fertilizers follow soon behind. The impacts of sanctions were expected to increase with time, perhaps taking months to become realizable or predictable.

Importantly, because different countries and regions source fertilizer products from different places, the impact of the war will disproportionately impact some regions more than others. Phosphate rock exports from Russia will be impacted but limited to specific countries: Russia has been supplying 7% of the global phosphate rock exports, with ~0.75 Mt going to Lithuania, ~0.75 Mt to Belgium, ~0.5 Mt to Norway, and smaller amounts to Belarus and Romania. Beyond phosphate rock, the most negative impacts are predicted in Brazil, where 28%, or ~3 Mt, of their total ~11 Mt of MOP imports is sourced from Russia. In fact, a presentation on Day 2 of the meeting by Priscila Richetti from Yara reinforced the historical growth of food production in Brazil and the paralleled consumption of fertilizer; total consumption has approximately doubled from 2010 to 2021, with P representing ~33% of the share in 2021. In the days following the meeting, several news outlets reported that Brazil would seek to source increased fertilizer supplies from Canada. By comparison, Europe and the U.S. had been sourcing ~20-30% and 8-15% of their fertilizer imports from Russia, respectively, though both have lower total volume of imports.

Ammonia was seen as the high risk because Russia has been supplying 23% of the global export share, along with 50% of the AN share, and 25% of the UAN share. Sales to Russia from other countries are also disrupted, e.g. the fertilizer manufacturer EuroChem reported 20% of its 2021 sales went to Russia. Again, how these various supply chain disruptions will affect fertilizer availability and sales is not yet predictable, and those disruptions will clearly have further downstream consequences to the agricultural and food systems sectors.

Also included in the markets agenda was a presentation by Bruce Bodine, Senior Vice President – North America of the Mosaic Company, titled, “North American market outlook.” Bodine emphasized the impact of Mosaic in Florida, citing the capacity to produce 10 Mt of phosphate fertilizer per year, 60% of which is retained in North America and 40% of which is shipped to offshore markets. This large commercial activity helps to sustain jobs and the economy of the State of Florida: Bodine quoted that the Port of Tampa’s economic activity is 70% phosphate-related, that Mosaic employs about 3,000 employees and 3,000 contractors, and that exports from Florida are valued at $1.8B USD. Weather was cited as a key swing factor in future market dynamics, especially droughts, which dominate the western U.S. Total 2022 North American shipments are expected to moderate from a record level in 2021 due to the higher prices that are driven by global supply constraints.

Ben Pratt, Senior Vice President for Government and Public affairs at the Mosaic Company then discussed sustainable Environmental, Social, and Governance (ESG) practices at Mosaic, an initiative within one of six Strategic Alignment Goals called “Act Responsibly.” Pratt presented 13 targeted milestones in areas covering diversity and inclusion (D&I) and environmental impacts such as greenhouse gas (GHG) emissions and freshwater use. Concerning GHG emissions, specifically, Mosaic targets reducing net GHG emissions to zero in Florida by 2030 and to zero, company-wide, by 2040. Mosaic projects to reduce freshwater use per tonne of product 20% by 2025. The year of this meeting – in 2022 – Mosaic launched global D&I targets that state, by the year 2030, Mosaic will have reached 30% women in the workplace, 30% growth in underrepresented groups in the workplace, and a 30% growth in leadership diversity. In the Q&A period, Pratt further reinforced the importance of an inclusive culture by adding, “a culture of inclusion must be there first – before diversifying your workforce.”

The technical agenda included several presentations by companies working in sustainability. Technologies from Novaphos were presented by their CEO, Tim Cotton. Novaphos targets reductions or eliminations in gypsum and mine tailings by introducing alternative technologies to produce phosphoric acid and a new calcium silicate solid called J-Rox, which has sufficiently low radioactive emissions to enable its use in structural and building materials. A product called Crystal Green from Ostara Nutrient Solutions was presented by their CTO, Ahren Britton, which is proposed to be used in parallel with traditional fertilizers. Crystal Green is a root-activated enhanced efficiency phosphate fertilizer which is produced via struvite precipitation and activates in soils in response to organic acids produced from growing roots. Britton reported the results of some studies that show increased yield with less total fertilizer application and reduced nutrient loss to waterways. The product Rhizosorb from Phospholutions was introduced by their CEO, Hunter Swisher. Swisher reported that Rhizosorb had been proven in 2021 on-farm and across 12 U.S. states and that they are now proceeding to test co-granulated formulations. Swisher reports that Rhizosorb maintains yields while reducing the amount of P required by 50%, which decreases nutrient pollution.

Finally, I’ll conclude by highlighting the presentation given by Catherine Thise, Marketing & Innovation Consultant at Marktrack. While Thise’s presentation was on the topic of market developments in phosphate recovery from sewage sludge, she opened with an acknowledgement that the day of her presentation was International Women’s Day, a powerful statement that uplifted diversity and inclusion in the industry. Thise motivated her talk by reinforcing many of the discussion topics in the sustainable P community, including the UN Sustainable Development Goals, continued rising interest in a circular economy for P, and geopolitical aspects including reference to population increases and global urbanization. Thise made the argument that, while sewage sludge and/or the ash produced from incineration of such sewage sludge can be made into fertilizers for agriculture (in fact, countless technologies exist for doing so), there remain significant barriers to global implementation of these processes, e.g. the remaining presence of heavy metals and regulation. Thise says, “The question is not ‘is there a technology to recover phosphate from sewage sludge?’,” but rather, “How do we valorize recovered phosphates?” and “Is there an economical interest in recovering phosphates?” Inspired by the Circular Economy Action Plan from the European Commission in March of 2020, Thise argues for valorization of P from waste products for applications, e.g., in electronics and batteries. With the rise in P demand in specialty markets, e.g. LFP batteries, her questions demand deep consideration. While important to pursue, these questions will also be challenging to answer.

Her final question, on the other hand, may be more straightforward to answer: “Should we compete or collaborate for a more sustainable world?” In my opinion, we could benefit from a complementary dose of both. Bill Gates is quoted as saying both, “Whether it’s Google or Apple or free software, we’ve got some fantastic competitors and it keeps us on our toes,” as well as, “Our success has really been based on partnerships from the very beginning.” In late celebration of International Women’s Day, let’s also pull from the words of American author Helen Keller, who said, “Alone we can do so little; together we can do so much.” Keller was awarded the Presidential Medal of Freedom from President Lyndon B. Johnson in 1964, the highest civil honor in the U.S. for peacetime service. With a war broken out in Europe and disruptions in critical supplies of nutrients to feed the world, now is certainly one of the more important times to work together.

Jacob L. Jones is the Kobe Steel Distinguished Professor of Materials Science & Engineering at North Carolina State University and Director of the Science and Technologies for Phosphorus Sustainability (STEPS) Center, a U.S. National Science Foundation (NSF) Science and Technology Center (STC). Any opinions, findings and conclusions or recommendations expressed in this post are those of the author and do not necessarily reflect the views of the NSF or the Sustainable Phosphorus Alliance.

PTraM Wins $750K to Study P Dynamics in Tile Drained Landscapes

By Matt Scholz of the Sustainable Phosphorus Alliance

Matt Scholz

Members of the Alliance’s P transport modeling (PTraM) group recently won a $750,000 applied research grant through the USDA-NIFA-AFRI foundational funding program. The project entitled “Advancing knowledge and prediction of phosphorus dynamics in tile drained landscapes” will involve interdisciplinary collaborations among soil scientists and watershed modelers. The four-year project aims to improve our understanding of phosphorus (P) loss in tile drainage systems and to improve tile P simulation in the Soil Water Assessment Tool (SWAT), a watershed scale hydrology and nutrient transport model.

“Our long-term goal is to provide science-based information to farmers and other stakeholder groups to support sustainable agricultural production while promoting water quality.”, said Dr. Vinayak Shedekar, who is leading the research project. “Watershed models like SWAT are often used for identifying critical source areas of these nutrients and to evaluate the efficacy of conservation practices in improving water quality. The stakeholder group plays a critical role in our work by informing our models with more realistic (on-the-ground) information. They also help us identify opportunities for improvement of these models. This project is perfect example of stakeholder-driven research and outreach,” said Shedekar.

The main focus area of the project will be the Western Lake Erie Basin (WLEB), where P transported via surface and subsurface flows from agricultural systems plays a major role in water quality impairments downstream, including harmful algal blooms (HABs). In heavily tile-drained agricultural landscapes of the WLEB, understanding and quantifying dynamics of dissolved P (DP) transport through tile drainage is critical. Dr. Chad Penn, a soil scientist at the USDA-ARS National Soil Erosion Laboratory explains, “While the transport of total P (TP) and DP have been extensively studied, knowledge and modeling gaps exist in relating soil properties with sorption dynamics and P transport through matrix and preferential flow pathways. Poor representation of P sorption and transport processes impact the usefulness of watershed models in guiding environmental policy.”

Dr. Penn has developed novel laboratory methods that help characterize the process of P desorption from topsoils and sorption by subsoils under different flow regimes. The knowledge from laboratory studies will then help improve the theoretical framework in the SWAT model, by adopting mathematical models of P dynamics and improving the representation of preferential and matrix flow to tile drains.

Dr. Margaret Kalcic will lead the watershed modeling research for the project with the help of field-scale monitoring data from within the watershed. “These possible source code modifications in SWAT will be an important improvement, especially for the WLEB, said Kalcic. Dr. Kevin King leads an extensive edge-of-field monitoring network in Ohio and plans to contribute monitoring data that would eventually help validate the proposed SWAT model improvements. The Alliance, including Dr. Rebecca Muenich, will play an advisory role on the model improvements and help with the dissemination of the information.

Alliance Helps Lead Major P Research Center

By Matt Scholz

The National Science Foundation has awarded $25 million to a major new phosphorus sustainability research initiative called the Science and Technologies for Phosphorus Sustainability (STEPS) Center. Headquartered at North Carolina State University, STEPS is the largest phosphorus sustainability program ever funded in the world. “This scale of research investment is required to address the wicked and time-sensitive challenges posed by the phosphorus sustainability problem in a way that can advance adoptable and sustainable solutions”, said STEPS Center Director, Dr. Jacob Jones of NCSU.

The Sustainable Phosphorus Alliance played a key role in the development of the proposal and will continue to help lead the knowledge transfer activities of the work, including its stakeholder engagement, public education, and IP aspects. The new Center is a natural evolution from the 2011 Phosphorus Sustainability Research Coordination Network (P-RCN) that was established under by our Director, Dr. Jim Elser, and managed in its later years by me. That project birthed the Sustainable Phosphorus Alliance and developed a network of stakeholders that will be carried into the new STEPS center, creating a vast new network of researchers and practitioners both in North America and abroad.

The mission of the STEPS center is to make a transformative improvement in the sustainable management of the phosphorus cycle in 25 years, leading to enhanced resilience of the food system and reduced environmental pressures. This includes reducing both dependence on mined phosphates and losses of phosphorus via point and non-point sources.

The Center adopts a “convergence science” approach by bringing together a diverse set of disciplines that address scientific challenges spanning the molecular scale to the global scale. Researchers within the program hail from 9 different US institutions and have a wide range of expertise, including materials science; civil, chemical, environmental, genetic, and agricultural engineering; crop, soil, and water science; computer science; chemistry; economics; sociology; forestry; and education. Central to the project will be a unique informatics hub for collecting and curating multiform data that will be incorporated into customized machine learning and artificial intelligence frameworks to help drive innovation, particularly in the space of materials development.

Broadly, research integrates across three thematic areas:

  • Theme 1 integrates diverse expertise in materials informatics with physico-chemical and biological material design and analysis to develop novel molecular motifs, surface chemistries, and topographies. The goal is synthesis of bulk materials, nanomaterials, coatings on textiles, or solid devices for effectively and selectively capturing and releasing phosphorus species or decomposing organophosphate.
  • Theme 2 explores new ways to incorporate phosphorus-capturing materials into scaffolds, supports, or other substrates tailored to the constraints of the environmental or engineered system and deploys novel materials and technologies from Theme 1 into simulated and real-world situations (e.g., soil types). Theme 2 incorporates aspects of socio-economics and policy from Theme 3 (below) to offer specific feedback on the performance of materials and technologies developed by Theme 1.
  • Theme 3 conducts spatial modeling of phosphorus sinks and sources and techno-economic analysis of local and national-scale scenarios. It then links that work with “spatial allocation optimization frameworks” that incorporate stakeholder preferences surrounding technology adoption and environmental sustainability to suggest realistic intervention portfolios across watersheds and socioeconomic conditions.

To help translate the research science to real-world application, the Center leverages what it calls its three “Triple-Bottom-Line Scenario Sites”, geographical testbeds for much of the research that will be conducted. These sites include the Tidewater Research Station in North Carolina, a 1550 acre research extension station that has run a 54-year-long P buildup and drawdown experiment; the Central Arizona-Phoenix Long-Term Ecological Research (CAP-LTER) site, which includes sites of urban ecology, wastewater treatment, and municipal organic waste collection; and Lake Okeechobee, Everglades Agricultural Area, and Everglades National Park, including researchers at the Everglades and Indian River Research and Education Centers, which are agricultural sciences research and outreach hubs.

Finally, a major component of the research center is its educational programming, which aims to recruit, train, and graduate a diverse cadre of intersectional researchers who are prepared for the type of convergent research necessary to drive solutions in this space. A core value of STEPS is to broaden the participation of women and underrepresented minorities within this student body, as well as within its faculty and staff and its stakeholder community.

We can all look forward soon to loads of collaborative STEPS-SPA programming, including a joint Phosphorus Forum, an international P sustainability conference, webinars and much more. Buckle up!

A Long Journey to a Book About Phosphorus

By Jim Elser, Sustainable Phosphorus Alliance, and Phil Haygarth, Lancaster University, UK

Does the world need a book about phosphorus? In 2010 Jim decided that the answer was “yes”, reflecting his belief that phosphorus was a greatly under-appreciated element given its huge importance for all of life and its pressing role in driving water pollution and in supporting food production. But what was missing, perhaps, was the perspective of scientists who work actively on this conundrum writing from the depth of their scientific expertise but in a non-technical form. The book would help awaken those in the world who were not scientific specialists and knew little about phosphorus, telling a story that wasn’t being told under one cover.

The book began to take shape during Jim’s sabbatical leave in 2010 but, like most such sabbaticals, there wasn’t enough time to finish and several chapters were left hanging. Luckily, Jim found a solution when, in 2015, Phil joined Jim’s NSF-funded Research Coordination Network on P sustainability. Phil had the expertise to contribute to chapters on soil, farming, watershed management, and water quality impacts so he was brought into the effort. In 2017 and 2018, final chapters were written and, after polishing and development of figures, the book manuscript was submitted to Oxford University Press in winter of 2019 and officially published on Christmas Eve, 2020.

The bound copy has 202 pages (not including literature and index), encompassing 10 chapters and an epilogue. What will you find among its pages?

Chapter 1: Here we provide a high-level view of the book and its coverage, highlighting the role of P in our everyday lives and describing the global phosphorus cycle, both in its “natural” form and its highly modified, industrial form of the present day. The reader learns that the human body contains about 0.62 kg of P and, over a lifetime, the average human will consume about 34 kg of P.

Chapter 2: Opening with the story of Hennig Brand’s discovery of P by distilling large amounts of urine, the chapter presents the structure of the P atom, along with a discussion of how elements are formed in both Big Bang and stellar nucleosynthesis. As it turns out, a P atom is created by smashing together two oxygen atoms at a temperature of a billion degrees Kelvin.

Chapter 3: Here we bring phosphorus to life, noting its essential role in the molecules of genetic information processing (DNA and RNA), in the currency molecule of energetic exchange (ATP), in the membranes that envelope all cells (phospholipids), and in our very bones (the mineral apatite).

Chapter 4: Next we discuss how P is assimilated from food and closely regulated in the body via excretion by the kidney. The essential role of P for animal nutrition (including humans) is discussed, including effects of insufficient and excessive intake.

Chapter 5: Chapter 5 begins to establish the close association between P and agriculture, discussing how humans once passively received P from foraging and hunting and now actively mobilize P via mining and large-scale agriculture. The dynamics of P in soil are summarized, and we highlight the strong reliance of modern crop varieties on heavy inputs of P fertilizer.

Chapter 6: This chapter takes a historical view of P-driven eutrophication, algal blooms, and dead zones. We discuss how the problem shifted from point sources of P (detergents, sewage outfalls) that were relatively straightforward (though expensive) to mitigate to non-point sources (agricultural runoff, manure losses) that are much harder to manage.

Chapter 7: Chapter 7 traces the history of the emerging phosphorus sustainability movement from when the 2007/2008 price spike in phosphate rock first raised concerns about long-term availability of phosphate fertilizers. We discuss various global efforts to raise awareness about the complex issues surrounding both P supply and P impacts and potential solutions.

Chapter 8: Here we begin to describe a set of mitigation strategies to enhance phosphorus sustainability, from improved crop varieties to better on-farm practices to enhancement of food chain efficiency by reducing food waste to reduction of meat and dairy in the diet (including meat substitutes and stem cell meat).

Chapter 9: This chapter discusses developments on the other side of the P sustainability coin: recycling of P. Emerging approaches from struvite precipitation in wastewater plants to anaerobic bioreactors to treat manure to ecological sanitation are reviewed.

Chapter 10: Here we bring the book’s themes together to argue for a new approach to the P sustainability challenge, one that doesn’t solely rely on piecemeal techo-innovation tricks but one that takes a systems-level approach that connects all dimensions of the complex global food-water system that touch on phosphorus.

Epilogue: We recount our wide-ranging conversation with Alliance Program Manager, Matt Scholz, as we tried to bring the book to completion and the ensuing road trip from Phoenix to San Diego to announce the book’s completion to the annual meeting of the Soil Science Society of America.

We hope that this book will help raise the profile of phosphorus in the broader community because solving the phosphorus conundrum is just as essential for ensuring future human well-being as is addressing other pressing issues such as climate change. And don’t you think everyone should know more about the 0.62 kg of something they carry around in their bodies every day?

The book can be purchased in hardcover or ebook form via Amazon and in hardcover via the Oxford University Press website.

SERA-17 Meets Virtually to Discuss P

By Matt Scholz, Sustainable Phosphorus Alliance

Matt Scholz

The SERA-17 information exchange group hosted its annual meeting virtually on October 15, emceed by their Chair, Dr. John Kovar of the USDA-ARS in Ames, Iowa. The group includes research scientists, policy makers, extension personnel, and educators, and its mission is “to develop and promote innovative solutions to minimize phosphorus losses from agriculture.” If you haven’t attended their meetings and are interested in understanding phosphorus sustainability in agricultural settings, I highly recommend them.

Fertilizer Recommendation Support Tool

This year’s program included four talks on work that the group is undertaking. The first talk, by Dr. Deanna Osmond of North Carolina State University, described the development of the Fertilizer Recommendation Support Tool (FRST). The project team, inspired by an Australian effort, recognizes inconsistencies in how soil tests are being used to develop fertilizer application recommendations and seeks to develop a national database and decision tool for delivering more consistent and science-driven recommendations. The project involves numerous collaborators from across the country and receives funding by USDA-ARS and –NRCS.

Dr. Osmond described how the team has surveyed current fertility practices and recommendations from across the country and has received 60 responses from 48 US states to date. Data have also already been collected from journal articles, factsheets, and other sources, representing 1238 field trials that have taken place between 1949-2018 in 34 states and across 13 types of crops. However, many data remain to be collected. The team is in the process of defining minimum requirements for datasets with the hope of standardizing the data it deposits in its database, thereby facilitating data meta-analysis. They have also studied how to develop a cloud-based decision support tool with an ArcGIS interface. Envisioned tool users include farmers, agricultural retailers, and researchers, among others.

Phosphorus Trade-offs Project

In the second presentation, Dr. Andrew Sharpley of the University of Arkansas described ongoing work undertaken in collaboration with USDA-NRCS that seeks to update current NRCS conservation practice guidance documents with information about tradeoffs farmers should consider when implementing specific practices. Three classes of practices are analyzed, including practices around avoiding over/mis-application of fertilizer (e.g. 4R practices), those around controlling erosion and runoff (e.g no-till and cover crops), and those around trapping nutrients that leave the field (e.g. wetlands and buffer strips).

Dr. Sharpley described how there is no “one-size-fits-all” approach to conservation practices. For example, no-till agriculture may reduce erosion, but can increase soluble P in runoff in some settings. Potential solutions in these settings include using subsurface application/incorporation, intermittent plowing, etc. As another example, buffer strips have “life expectancies” after which they can shift from phosphorus sinks to sources; potential solutions include harvesting forage from the strips or amending them with trapping byproducts such as FDG-gypsum. Dr. Sharpley emphasized that improving soil health alone will not eliminate nutrient runoff, and there is a need for adaptive management of conservation practices and to keep soil test phosphorus values in the “optimal” range. These types of analyses will be provided in updated, user-friendly documents to farmers, extension agents, and others.

Draft documents have been developed and will be circulated soon to relevant stakeholders. Overall, Dr. Sharpley encouraged an approach to nutrient management in fields akin to medical management in patients: triage (assess), diagnose, prescribe, and monitor to avoid unintended consequences.

4R Practice Implementation in the Northern Great Plains

Dr. Lindsay Pease of the University of Minnesota described a cross-border, 4R nutrient management project, which she has undertaken in collaboration with the Canadian universities of Manitoba and Waterloo, that is focused on the Red River basin. The group have established an edge-of-field monitoring project in Crookston and have collected a year of preliminary data on how implementing 4R practices affects phosphorus losses in both tile-drained and undrained soils. The project will continue for 4 more years and will lead to the production of outreach and extension materials based on the results.

USDA LTAR Phosphorus Balance Project

Dr. Pauline Welikhe of Purdue University explained her Network P Budget Project, undertaken through the USDA’s Long-Term Agroecosystem Research (LTAR) network, which was established by USDA to facilitate sustainable intensification of agriculture. The project has sent collaborators from around US and Canada data collection forms to capture information needed to develop P budgets at the soil-plant-system level, essentially looking at the difference between the phosphorus added to a crop minus that removed by its harvest. It does not generate new data, but rather collects data already in hand, and has done so from 19 sites and 41 agricultural systems thus far. Variability across agricultural systems will be analyzed as will the influence of fertilizer source on the phosphorus balance. Where data are missing, her team is working with the collaborators to either fill in the gaps with existing data or define research needs where no data exist.

Featured Member: Renewable Nutrients

Renewable Nutrients logo

North-Carolina-based Renewable Nutrients offers combined nitrogen and phosphorus extraction and recovery technologies to solve the total nutrient issue for high strength streams. It is a founding member of the Sustainable Phosphorus Alliance, and CEO Jeff Dawson serves on our Board of Directors.

How big is your company and where does it operate?

Renewable Nutrients is a small American based startup company commercializing USDA nutrient recovery technologies.

What does your company do related to phosphorus sustainability?

Renewable Nutrients is currently commercializing a technology called Quick Wash. Quick Wash is a phosphorus and ammonia recovery technology originally developed by the USDA. Our phosphorus technology can extract and recover more than 90% of the phosphorus found in waste streams. The recovered product can be used in a more efficient sustainable way and leaves behind low phosphorus biosolids and effluent water. Markets include municipal and private waste water treatment plants, animal and food waste to energy projects, as well as farming projects.

What’s your business model?

Renewable Nutrients has an extremely flexible business model. We are positioned to install and implement our technology on a full scale including operating and distribution of the byproduct. However, we will work with our customers who may want to retain the byproduct or run a model with low or no byproduct. Essentially our model is based on the customers issues around phosphorus, and we model the project to efficiently solve those unique problems.

What are the biggest challenges you face?

Regardless of the benefits of recovery and reuse of nutrient byproducts, we still see reluctance of end users willingness to change the way they think about addressing phosphorus limits or other issues driven by phosphorus and ammonia. We are very early in the recovery space and think long-term, with coordinated regulatory participation, we will see more operators looking for strategic ways to deal with phosphorus recovery.

Where do you see the biggest opportunities for advancing phosphorus sustainability?

I think by being agnostic on how we implement our technology and not needing a return on byproduct sales to justify an installation, we become uniquely positioned to provide recovery technology to smaller markets. Until we find a way to address this problem on a smaller scale, we will never fully penetrate the market opportunity that stands before us.

What’s been your biggest sustainability win?

Combining two technologies to recovery phosphorus and ammonia at the same time while creating two separate byproducts may be game changing for the implementation of Quick Wash. This will allow a client, for the same previous cost of just recovering phosphorus, to solve both their phosphorus and ammonia issues. If we can broaden the value of the technology, then we see clients with ammonia issues adding on phosphorus recovery as a very cost effective solution at the same time rather than punting the problem down the road.

Alliance’s Phosphorus Transport Modeling Group Meets

By Dr. Matt Scholz

Sustainable Phosphorus Alliance

Matt Scholz

The Sustainable Phosphorus Alliance hosted its second in-person workshop of what’s been rebranded as its Phosphorus Transport Modeling Group in San Antonio, Texas, on Nov 14-15. The meeting was held nearby, and just after, the meetings of the Soil Science Society of America and SERA-17. Fourteen academics and practitioners met for the workshop with an additional two joining via phone. The meeting was underwritten in part by USDA-ARS.

The working group originally formed in 2018 to address issues of how to better harmonize field-scale hydrological models of phosphorus fate and transport, such as the Annual Phosphorus Loss Estimator Tool (APLE), with watershed-scale models, such as the Soil and Water Assessment Tool (SWAT), and how to address knowledge gaps evident across all models (e.g. specific transport phenomena not modeled). These models are often applied to validate P indices and estimate P loads into impaired waterbodies, for example. They vary not only in spatial and temporal scales, but in data requirements, sophistication, and ease-of-use. In the time since the original group formed, it has extended its purview to study how field- and watershed-scale models can inform regional models of phosphorus flows as well. For example, transport models may inform assumptions about P losses from manure application that are made in regional, substance-flow models.

All good transport models are beholden to the same laws of physics and chemistry. While they should concur with each other and with edge-of-field data when analyzing identical scenarios, especially in general direction of change, there remains a need for cross-validation studies to demonstrate model agreement. We also need to develop frameworks for integrating these models across scales. For instance, APLE’s extrapolation of total P losses from agricultural fields within a watershed should be similar in magnitude to the watershed-scale predictions of SWAT, and both models should jibe with edge-of-field data on total P losses. Where they don’t, we can identify further research needs for model improvements and integration. Furthermore, the models would ideally confirm and help provide a sound scientific underpinning to decision support tools, such as phosphorus indices. The latter can be accomplished, for example, by leveraging model simulations to estimate more accurate weights when calculating scores in a P index.

The first day of the meeting provided time for group members to update one another on recent progress on related research, and the second day developed work items to be carried forward. One of the tasks accomplished was to develop a research agenda for a postdoc who will be working in Dr. Carl Bolster’s lab at the USDA-ARS research station in Bowling Green, Kentucky, on key research themes for the group. These include such themes as how we account for legacy versus incidental P losses within models, how P hotspots might be identified using hydrologic models, and how well different models agree in these identifications. We also identified a number of areas ripe for inquiry, including: How do we better incorporate plant growth models? How do we adapt models to be more useful in P deficient systems (e.g. sub Saharan Africa)? How does fertilizer formulation affect transport? What should agronomists be measuring to improve modeling?

On day two, we outlined a group paper on best practices in phosphorus fate and transport modeling in agricultural settings. There is considerable room for user error in applying models to scenarios, and we aim through the paper to provide guidance on best practices for model use: What models are best used when? How well do specific scenarios pair with models? What questions can be asked and how long will it take to get an answer? We also discussed funding and outreach opportunities for the group.

The group was joined by 4 representatives from the Moroccan phosphate mining company OCP (foundational supporter of the Alliance) and the Moroccan l’Université Mohammed VI Polytechnique (UM6P). They were particularly interested in how such models might apply to the African context.

Collectively, this Phosphorus Transport Modeling Group set its sights on the ambitious goal of establishing the group as the “go-to” group for phosphorus fate and transport modeling questions. The Sustainable Phosphorus Alliance has built a steering committee, a web page, and other infrastructure to facilitate the group’s collaboration. Readers can look forward to future reports, including a presentation from Dr. Carl Bolster at our Phosphorus Forum 2020 event in Washington DC on April 30.

Participation in the working group is a benefit of Alliance membership and by invitation of the steering committee. Please contact us for further information.

A Tool for Trapping Dissolved Phosphorus

By Dr. Chad Penn

USDA-ARS, National Soil Erosion Research Laboratory

The P removal structure is a large, landscape scale filter for dissolved phosphorus (DP), intended to intercept and trap P from “hot spots” (i.e. legacy P) before reaching a surface water body. The P removal structure embodies four basic principles:

  1. Contains solid media with high affinity for P, commonly known as a “P sorption material”, or PSM.
  2. PSM is contained and placed in a hydrologically active area with high dissolved P concentrations.
  3. High DP water is able to flow through the contained PSM at a sufficient rate and contact time. Structures must be designed to handle peak flow rates since 90% of annual P losses are generally transported in less than 5% of the flow events, which are the largest flow events.
  4. The PSM is able to be removed and replaced after it is no longer effective.

Due to small amounts of PSM, poor contact between PSM and flowing water, and limited contact time, small in-line pipe filters and “socks” filled with filter media are not effective for removing appreciable amounts of P, nor do they remain effective for any significant amount of time. If a site contains appreciable P loads worth treating, then it will require several tons of filter media.

Phosphorus Sorption Materials (PSMs)

Many PSMs are by-products from different industries, and therefore can be obtained for low cost. Some PSMs are manufactured. However, all PSMs must first be screened for safety before use in a P removal structure. Some examples are shown below.

Types of P Removal Structures

P removal structures can appear in many different forms. They can be located on the surface or subsurface, in ditches, tile drains, drainage swales, drop inlets, blind/surface inlets, etc. Any unit that embodies the four basic principles is essentially a P removal structure. Several examples of P removal structures are shown.

Choosing an Ideal Location

In order to qualify as a potential site for construction of a P removal structure, a site must possess:

  1. Flow convergence to a point where water can be directed into a structure, or the ability to manipulate the landscape
  2. At least 0.2 ppm dissolved P (DP) in water
  3. Hydraulic head required to “push” water through structure: function of elevation change or drainage ditch depth
  4. Sufficient space to accommodate PSM

P removal structures are not a “silver bullet”, as they are intended only for sites that are legacy P sources, that is, excessive soil P concentrations that will remain elevated for decades, releasing dissolved P into drainage water even after ceasing P applications. This best management practice is not intended for trapping incidental losses of P from recently applied manure or fertilizer, as there are much less expensive BMPs for that type of P source, such as incorporation and proper timing of application.

Designing a P Removal Structure

Several inputs and target goals are required for designing a site-specific structure. The P-Trap software, which will soon become publicly available through the USDA-ARS, can be used to quickly design a structure with any effective and available PSM.

Example P Removal Structures

The confined bed structure shown above contained 40 tons of treated steel slag and intercepted runoff from a poultry farm with DP ranging from 2-15 ppm. This structure was able to remove 7.5 lbs DP in 2.5 yrs and handle ~1000 GPM flow.

The tile drain P filter shown above during construction, utilized a conventional septic tank. This structure contains 2.5 tons of a manufactured PSM (Fe-coated alumina) that can be regenerated after becoming saturated with P. This unit was designed to remove 40% of the 10 year cumulative DP load, and handle 300 GPM. After 10 years, the PSM will be regenerated in-situ. For more information about how these types of structures are designed and work, please see our video here.

Cost and Justification

The only other conservation practice that can truly remove P is soil P drawdown via plant uptake and harvest. Although necessary for solving the long term problem of legacy P, it requires many years (decades) for plant draw-down to reduce DP concentrations in drainage water. During that long draw-down period while dissolved P losses are still elevated, P removal structures can be used to trap P in drainage water. Cost of structures will vary dramatically with site and PSM utilized. Total costs are similar to waste water treatment: $50-500 dollars per pound of P removed.

Current and Future Efforts

Current research is focused on regeneration of PSMs and investigation of new by-products for reducing costs. The ability to regenerate PSMs in-situ, even once, will nearly cut the cost of P removal in half. The USDA-ARS National Soil Erosion Research Laboratory is also working closely with the NRCS, American Society of Agricultural and Biological Engineering, and American Society of Agronomy, in producing a series of training videos and certification program for design and construction of P removal structures. The P-Trap software will also aid in increasing the adoption of this new BMP. Many states include the P removal structure in their cost-share program, under the 782 Standard.

For more information, please contact Dr. Chad Penn at the USDA-ARS (

Additional Sources:

Penn, C.J., and J.M. Bowen. 2017. Design and construction of P removal structures for improving water quality. Springer Publishing. ISBN 978-3-319-58657-1

Penn, Chagas, Klimeski, and Lyngsie. A Review of Phosphorus Removal Structures: How to Assess and Compare Their Performance. Water (20734441), August 2017. DOI 10.3390/w9080583

USDA-ARS National Soil Erosion Laboratory – water filtration system and P-TRAP application video

Opinions expressed here do not necessarily reflect those of the Sustainable Phosphorus Alliance.


OCP: Feeding the Soil to Feed the Planet

By Krista Maruca of OCP North America

Krista Maruca

OCP Group is a global player with a leadership position across the phosphate value chain in extracting, marketing and selling phosphate and its derivatives. As the top global producer of phosphate in all its forms – rock, acid, and phosphate-based fertilizer – OCP has a strong international presence on all five continents. Recognizing the significant role OCP plays at the top of the value chain as a supplier of the world’s phosphate needs, the company joined the Sustainable Phosphorus Alliance as a foundational supporter and board member at its launch in 2016.

OCP’s Approach to Phosphorus Sustainability

OCP’s unique position requires continually striving to innovate in order to improve environmental sustainability and phosphorus efficiency. As part of that mission, OCP has set ambitious goals with the launch of its Circular Economy program in 2018, which is oriented around four pillars: natural resource preservation, sustainable production, smart consumption, and creation of value through transformation and recycling. This circular approach aims to better integrate its industrial ecosystem with the natural environment and communities in which it operates. In its industrial operations, OCP has publicly committed to goals to transition to 100% green power through solar, wind, and co-generation; zero consumption of public water resources through desalination and purification of wastewater; a reduction in emissions and waste by-products through the use of newly available technology; and to maximize the value of low-content phosphate and other recoverable minerals. Those goals are well on their way to being met through significant investments in new technology to more efficiently source phosphorus.

In the US, OCP’s North American subsidiary has set in motion plans to further the mission of sustainable phosphorus on a local level. On-farm nutrient management has come under the national spotlight in recent years due to highly visible algal blooms that disrupt local business, tourism, and recreation. In some years, when adverse weather conditions lead to a particularly nasty bloom, the issue has risen to crisis levels. The science of phosphorus runoff is complex, with fertilizers’ application rate, timing, source, and placement all playing a role in phosphorus losses to the environment. Moreover, fields with various soil types and management histories have divergent needs, meaning there is no one-size-fits-all solution to reduce runoff. 4R Nutrient Stewardship — working with farmers to ensure applications are at the right place, right time, right rate, and right source — is one approach to close the loop on phosphorus losses. Responsible nutrient stewardship can minimize impact on the environment and rural communities and has positive impacts for the farmers we serve by advancing soil health and productivity. OCP North America is a partner in the 4R effort to promote sustainable on-farm management of phosphorus in the US and Canada.

Platform for Scientific Research and Collaboration

Joining the Sustainable Phosphorus Alliance is not only in line with OCP’s own corporate mission but also fills an important need for the sector more broadly. As farming communities and local policy-makers grapple with ways to reduce nutrient loading into waterways and limit waste, there is a greater need for collaborative research that will provide a scientific basis of understanding of the complex issues of soil health, water quality, and phosphorus management. The Alliance’s ability to bring together technical experts from industry and academia is the first step to advancing shared knowledge of phosphorus dynamics and ensuring evidence-based decision-making.

OCP is proud to contribute to this effort, including by making it a focus of faculty and students at the University Mohammed VI Polytechnique (UM6P). Inaugurated in January 2017 and housed in Ben Guerir, Morocco, several UM6P programs and joint research projects tackle challenges linked to phosphorus sustainability. At the School of Agriculture, Fertilizers, and Environmental Sciences, students learn about environmental conditions in African agriculture for preserving water, soil quality, and natural resources. Programs in industrial operations build upon mining and fertilizer manufacturing technology, including through a new experimental mine that provides a full-scale living lab for developing new innovations in phosphate mining. Exchanges with the scientific community in the Alliance network offer the opportunity for UM6P researchers to contribute to the growing body of global knowledge on phosphorus sustainability.

Making a real impact on phosphorus use efficiency will require collaboration across all players in the value chain; the Alliance creates that space by providing a platform for cooperation and new partnerships. OCP is looking forward to continuing its leadership in the Alliance and building relationships with other new members in the coming years.

Opinions expressed here do not necessarily reflect those of the Sustainable Phosphorus Alliance.

About OCP North America

The OCP Group is the world’s largest exporter of phosphate rock and phosphoric acid, as well as one of the world’s largest producers of fertilizer. The company is integrated across the entire phosphate value chain, extracting, marketing and selling phosphate and its derivatives, phosphoric acid, and fertilizers. Headquartered in Morocco, the OCP Group is the largest corporate employer in the country. OCP’s North American subsidiary was launched as OCP Research LLC in 2016 and transitioned to OCP North America in February 2019 to manage its engagements across the U.S. and Canada.


The Phosphorus Sustainability Challenge

By Matt Scholz of the Sustainable Phosphorus Alliance

Matt Scholz

Phosphorus is both a vital nutrient upon which global agriculture depends and a devastating pollutant of our planet’s freshwater resources. The Sustainable Phosphorus Alliance is committed to managing this finite resource sustainably, and we’re inspiring collective action towards better phosphorus management through the launch this April of our Phosphorus Sustainability Challenge.

Worldwide, many organizations work hard to manage our phosphorus resources sustainably. The Phosphorus Sustainability Challenge will be a place where they can gather to publicly commit to reducing their phosphorus footprint and to see how their individual efforts contribute to greater goals. These goals include using phosphorus more efficiently in crops and animal feed, diverting and removing phosphorus from our waters, and recovering and recycling phosphorus wastes—including food
wastes—back into the food system.

How will the Challenge work? Organizations will publically commit to reduce their collective phosphorus footprint. In return, they will receive public recognition for their leadership, see how their own efforts contribute to larger scale impacts, and network with like-minded organizations through sector-specific action networks. Commitments must be SMART: Specific in what they set out to achieve, Measurable on an annual basis, Ambitious in their targets, Relevant to Challenge goals, and Time-bound. Applicants will need to make new commitments or state existing commitments that have yet to be achieved or publicized, and all committments will have to go beyond what is required for regulatory compliance.

Who can participate? Any government at any jurisdictional level and any public or private institution or company of any size. The platform is being designed to allow everyone from transnational corporations to small, local groups to make meaningful contributions. We need all hands on deck.

How is it funded? The Challenge development is currently funded by the Sustainable Phosphorus Alliance but we seek foundational support. Please contact us if your organization would like to support our effort to keep our waters blue and our fields green.

How will achievement be verified? Participants who obtain third-party or second-party verification for their progress will be recognized as such on the platform upon submitting proof of verification. Otherwise, there is no verification required but commitments will be in the public record. Any verified misrepresentation of prior achievement will bar applicants from further participation in the Challenge.

The Challenge will be launched at our Phosphorus Forum on April 5, 2019. Please contact us for more details.

Notes from the Alliance’s 2018 Phosphorus Modeling Workshop

By Dr. Grey Evenson, Ohio State University

Grey Evenson

The Phosphorus Field-to-Watershed (P-F2W) Modeling Workshop brought 16 researchers and policy experts to Columbus, Ohio, on August 23rd and 24th. The group discussed soil test phosphorus measurements and their relationship to fertilizer application recommendations, status and trends of edge-of-field and in-stream water quality observations for the Maumee River basin (a tributary of Lake Erie and a major contributor of P loadings to the lake), and existing models to simulate soil phosphorus and their application in the Maumee basin.

Chad Penn (USDA-ARS) discussed how soil test phosphorus measurements are used to guide fertilizer application rates. Dr. Penn suggested that these recommendations provide good “ball-park” application recommendations but that they may be better tailored to the soil texture, the crop being grown, and other site conditions. He suggested that these improvements should improve agricultural efficiency while decreasing P loss from fields.

Laura Johnson (Heidelberg University) and Kevin King (USDA-ARS) presented their efforts to assess phosphorus loadings to Lake Erie using in-stream and edge-of-field monitoring networks, respectively. In summarizing long-term, in-stream observational data, Dr. Johnson showed that current, flow-weighted, mean dissolved P concentrations are consistent with historical trends – implying that recent efforts to decrease loadings to the Lake have not been successful, at least to this point in time. Dr. Johnson also suggested that the continuing problem may be partly attributed to increased soil P stratification (i.e. higher P concentrations at the top with lower concentration at greater depths) as a consequence of reduced tillage. Dr. King then described his network of edge-of-field sites that measure P loss from fields in surface and tile flow and noted that most of the monitored fields do not show excessive quantities of P export. Dr. King additionally discussed the impact of various best management practices as applied to these sites, reviewing the relative success of each.

Peter Vadas (USDA-ARS) and Margaret Kalcic (Ohio State University) discussed their work to simulate soil phosphorus dynamics using empirical and process-based models. Dr. Vadas reviewed the evolution of models that simulate soil phosphorus dynamics in agricultural systems – beginning with the EPIC model, then moving to the APEX, SWAT and APLE models. He described the individual “pools” of phosphorus (i.e., labile, active and stabile mineral phosphorus, and organic phosphorus) and emphasized that the labile mineral pool can be initialized using common soil test phosphorus measurements. He then outlined previous work to validate SWAT’s phosphorus routines and introduced his continuing work with the APLE model. Dr. Kalcic provided an overview of the SWAT model and recent applications of that model in the Maumee watershed. She then introduced a new iteration of the model – wherein the most basic spatial unit of simulation approximates the size of agricultural fields – and her ongoing efforts to validate SWAT’s simulation of soil phosphorus dynamics, including phosphorus export through surface and tile flow. She also discussed several challenges in simulating phosphorus in the Maumee – namely problems with calibration when initializing labile P at higher values and with the insensitivity of modeled crop growth to soil phosphorus levels.

Finally, Tom Zimnicki provided a summary of a workshop hosted by the Cooperative Institute for Great Lakes Research at the University of Michigan, Ann Arbor, in July 2018. The workshop hosted a number of researchers and sought to improve hydrologic model representation of soil health as impacted by agricultural best management practices.

Following presentations, the group plotted a path forward. Three specific areas of investigation were identified for additional discussion: identifying whether legacy or incidental losses were the primary sources of P loadings to Lake Erie; coupling fertilizer production, particularly from recycled organics, and watershed hydrologic models; and identifying “hotspots” (i.e. locations of elevated P export) using hydrologic models. The meeting was concluded by discussing plans to collaborate in investigation of these specific topics.

The workshop was organised by the Sustainable Phosphorus Alliance. The workshop agenda and presentation slidedecks are available for download in PDF format in the sidebar to the event listing on this page. In addition, you can view video of these talks on our YouTube channel.

Grey Evenson is a postdoctoral fellow in the Department of Food, Agricultural and Biological Engineering at Ohio State University. Grey is a watershed scientist with an interest in applying models to improve environmental outcomes. Opinions expressed here do not necessarily reflect those of the Sustainable Phosphorus Alliance.

Europe Continues to Move Nutrient Policies Forward

By Chris Thornton, European Sustainable Phosphorus Platform

Chris Thornton

The 3rd European Sustainable Phosphorus Conference (ESPC3) brought together 300 companies, policy makers and experts in Helsinki, June 2018. New EU policies announced include the obligation for farmers to implement nutrient budgets, the new EU Fertilisers Regulation and the draft Water Reuse Regulation. The ambitious new Fertilisers Regulation, currently under finalisation and part of the EU Circular Economy package, will fix quality and safety criteria for placing on the market recycled nutrient products including composts, digestates, organic fertilisers and soil improvers, recovered phosphate salts, biochars and ash-based products. The Water Use Regulation will fix quality and safety criteria for use of treated sewage discharge water for agricultural irrigation / fertigation.

Companies presented success stories showing that nutrient recycling is already operational through different routes including animal by-product incineration ashes, sewage biosolids, struvite, spent fire extinguisher chemical recycling, forestry and bio-energy by-products, gypsum and nitrogen recovery from digestate. Discussions confirmed the need for data, risk assessment science and dialogue around acceptance of recycled nutrient materials, both organic materials and technical recovered nutrients. The positive marketing message of nutrient and organic carbon recycling needs to be developed, alongside labelling and product traceability, in order to support acceptance of nutrient recycling in food and beverage industry and supermarket purchasing and sustainability criteria.

Despite considerable investments already made in waste water treatment, phosphorus continues to be one of the biggest challenges to water quality across Europe. Tighter sewage works phosphorus discharge consents are expected. New technologies combining phosphorus removal with recovery for recycling are being proposed. Approaches to remove nutrients from water bodies and sediments will be needed to restore eutrophication impacted waters, such as the Baltic Sea, with development of both restoration technologies and biological systems (such as harvesting of zooplankton consuming fish). Again, success will depend on product commercialisation, such as developing new recipes for such often not consumed fish.

The conference was organised by BSAG (Baltic Sea Action Group) and ESPP (European Sustainable Phosphorus Platform). Full conference summary in the ESPP SCOPE Newsletter n°127 ( and short article at

Opinions expressed here do not necessarily reflect those of the Sustainable Phosphorus Alliance.

Biosolids and Manure Task Force

Manure Task Force

Participation in a task force is one of the opportunities for our partners to contribute to the Sustainable Phosphorus Alliance. One example is our Biosolids and Manure Task Force, which undertook a comparative analysis of the federal and state regulations governing the application of biosolids and manure in the US and hopes to encompass Canada as well. That work has been embedded in an online tool, called GIS-P (rhymes with crispy), that presents the regulatory data alongside other contextualizing data in a geographically browsable format.

Member organizations of the Sustainable Phosphorus Alliance and other invitees from industry and government are contributing to the task force by providing oversight and feedback. Thank you to our Oversight Board members representing Kieser & Associates, Lystek International, Metropolitan Water Reclamation District of Greater Chicago, Mid-Atlantic Biosolids, National Association of Clean Water Agencies, National Milk Producers Federation, NEFCO, North East Biosolids & Residuals Association, Smithfield Foods, Synagro, US EPA, and Veolia.

The task force objectives are:

  • To compile and compare all state and federal regulations related to biosolids and manure land applications
  • To identify local variations in regulatory interpretations
  • To produce an online tool that facilitates study of the data, now available here

If you would like to support the work of the Sustainable Phosphorus Alliance, please contact us about joining as a member.

Alliance Launches Biosolids and Manure Project

By Matt Scholz of the Sustainable Phosphorus Alliance

Matt Scholz

While the recycling of many products has only taken hold in the past few decades, people have been recycling phosphorus for thousands of years through the collection and land application of animal and human wastes. Ancient Romans used manure as fertilizer, and ancient Athenians are said to have used sewage to fertilize groves and gardens around the city. Jump forward to 19th century New York, where night soil men would collect human waste from homes either to be land applied on farms or hauled to the city dump. (This makes me appreciate my job.)

We still land apply treated human waste (a.k.a. biosolids) to farms, but much of it is still sent to the city dump—45% according to a 2007 report from NEBRA—thereby wasting our phosphorus resources. Annually, we generate about 350,000 tons of phosphorus as biosolids in the US alone (c.f. Chris Peot’s Phosphorus Forum 2017 talk), so we estimate that about 157,500 tons of phosphorus is lost to landfills.

Land application of biosolids from wastewater, as well as manure from animal feeding operations and composted or digested biomass from farms and cities, is an important means of providing nutrients to crops and restoring soil carbon while diverting wastes from landfills. However, it can also result in over-application of nutrients, especially phosphorus, which can lead to adverse impacts on water quality. Most notably, the US produces upwards of 1.9 million tonnes of phosphorus in animal manure annually (US EPA, 2007) that is spread across more and more geographically constrained areas as consolidation of animal agriculture into concentrated animal feed operations (CAFOs) continues. Manure, especially wet, is heavy and expensive to transport, and that tempts its over-application. Yet over-applied phosphorus is carried by rains and other mechanisms to nearby waterways, resulting in harmful algal blooms and dead zones.

If only we could teleport manure.

A New Initiative

If there’s a global theme in phosphorus management, it’s resource misallocation. We have too much in some regions, too little in others, and too much wasted throughout the value chain. We want to encourage more efficient use of phosphorus, and we want to encourage its recycling in the food system through the sustainable land application of biosolids and manure, for example.

Recognizing this, the Sustainable Phosphorus Alliance has been asking industry and regulatory stakeholders to help us vet project proposals on sustainable use of organic residuals for the better part of a year, and we thank those of you who’ve provided feedback on those proposals. We are pleased to announce that we have decided to conduct a comparative landscape analysis of the regulations and policies affecting land application of biosolids and manure at the US federal and state levels and, resources permitting, at the Canadian federal and provincial levels. The work will be led by our own Dr. Rebecca Muenich with the help of some graduate student support.

Application of both biosolids and manure in the US is regulated under the Clean Water Act, but each is regulated under different sections. Namely, biosolids are regulated under 40 CFR Part 503, “Standards for the Use or Disposal of Sewage Sludge” and manure generated at CAFOs is regulated under the National Pollutant Discharge Elimination System. Much of the manure that is generated is not produced at CAFOs and isn’t subject to NPDES permitting. How regulations on both biosolids and manure management play out at state and regional levels varies. For example, the state of Michigan does not allow manure application on soils with greater than 150 ppm of P, whereas Indiana allows application on soils up to 200 ppm of P. Likewise, states treat biosolids variably. For example, Pennsylvania and Maryland permit use of the water extractable phosphorus test to determine a site-specific application rates, but other states regulate based on total phosphorus.

What consequences do these disparate treatments have for application of biosolids and manure and how might we develop policies that increase sustainable land application? The first step to addressing this question is understanding the regulatory landscape, and that’s precisely the goal of our work. We’ll be developing a white paper and webinar over the coming months on this topic. More exciting to me is our development of an ArcGIS Story Map that will allow users to navigate these regulations geographically through a web interface. This dataset can then serve as a scaffold upon which we can layer other relevant datasets, including such things as locations of CAFOs and wastewater utilties, soil test P levels, known areas of land application, etc. We hope this becomes a great tool for managers and policy makers to develop more sustainable scenarios.

To ensure relevancy and leverage past work on this topic, we’re reaching out to industry and regulatory partners to join an oversight board for the project. This board will provide feedback on a draft of our white paper and on the first rollout of the ArcGIS tool. If you think that your organization can lend expertise or other valuable resources, please contact me. We expect this first phase of the project to take about nine months to complete.
And if you would like to support our work more broadly, please join us as members.

Understanding Composition: One Key to Recycling Manure

By Rebecca Muenich of the Sustainable Phosphorus Alliance

Precision agriculture, the practice of employing monitoring systems, software, and equipment to modify farming inputs in a productive and efficient manner, is applied everywhere in modern agricultural systems, except when it comes to a majority of manure applications. Compared to inorganic fertilizer sources that have clearly documented, consistent compositions, manure and its associated nutrient values are not well appreciated and are even treated as waste by many farms in the US. This is especially true for large farms with a lot of liquid manure, including dairy and swine operations.

Research has shown the potential value of these recycled fertilizer products (Schröder 2004; Choudhary et al. 1996), so it is perhaps surprising that, in many places in the US, manure is treated as waste product and contaminant source rather than a nutritional opportunity. Understanding manure composition is key to addressing this problem. This is because variable composition has been identified as a barrier to farmers’ distribution or sales of their manure to other farms, especially non-livestock farms (Battel and Krueger 2005).

There are many references available to help calculate the nutrient content of manures, including the American Society for Agricultural and Biological Engineer’s “Manure Production and Characteristics” Technical standard ASAE D384.2, generalized table values available in many online extension publications (University of Maryland Extension; Ohio State Extension), and in permit information for regulated facilities. However, the micro- and macronutrient content of recycled fertilizers can vary dramatically by source and even over time. For manure specifically, it is well known that factors such as the feed an animal eats, the age, size, and species of animal, and the method of manure storage can all affect the nutrient content. Composition may also be affected by such practices as the addition of compost or water from other parts of the farm. In addition, the variation in methods for calculating nutrient content alone creates discrepancies.

In my work to understand manure application practices in the Lake Erie basin with colleagues at Ohio State University and the University of Michigan, we compared lab-measured nitrogen and phosphorus contents of manure to estimated “book values” for large, regulated animal operations where data were available. This comparison supported what others have found: that using book values alone may not be enough to understand the nutrient composition of excreted and/or stored manure. This variability can have important implications for farm economics as well as environmental management. Putting on too little or too much nutrients can put a farm at risk. Therefore, lab testing of manure nutrient content should be a preferred source for composition information.

We demonstrated on a small scale with very detailed data that there is a great potential to redistribute (i.e. recycle) manure by applying it to lands that have lower soil nutrient contents. It is often the case that cropland currently receiving manure applications is not in need of more, as a history of consistent manure applications can lead to a buildup of nutrients in the soil (Sharpley et al. 2013). Yet redistributing and applying manure at appropriate rates will require improvements in measuring and conveying the nutrient content of manure products to potential end users.

More frequent, replicated samples and more nuanced reporting are called for. In terms of reporting, manure composition tests may not break down the phosphorus in the sample into organic and inorganic forms, though they may indicate how much is available in the first year. Giving farmers a better idea of the total amount of phosphorus and its speciation (to assess bioavailability) can improve nutrient management. More testing is needed too. While testing manure compositions is required for large, regulated operations on typically an annual basis, it is not a widespread technique used in manure management, at least in the Lake Erie Basin states. On small farms with fewer resources, manure composition testing (~$30/sample) may not seem economically beneficial at first glance. However, if manure nutrients can contribute to crop nutrient needs, overall fertilizer additions may be decreased, saving money while decreasing the risk of nutrient pollution.

Improved and more frequent testing and communication of manure compositions is key in achieving the “Right rate” in 4R Nutrient Stewardship.

[Open source] Battel RD, Krueger DE. 2005. Barriers to change: Farmers’ willingness to adopt sustainable manure management practices. Journal of Extension, 43(4).

Choudhary M, Bailey LD, Grant CA. 1996. Review of the use of swine manure in crop production: Effects on yield and composition and on soil and water quality. Waste Management and Research, 14(6).

Schröder J. 2004. Revisiting the agronomic benefits of manure: a correct assessment and exploitation of its fertilizer value pares the environment. Bioresource Technology, 96(2): 253-261.

[Open source] Sharpley AS, Jarvie HP, Buda A, May L, Spears B, Kleinman P. 2013. Phosphorus legacy: Overcoming the effects of past management practices to mitigate future water quality impairment. Journal of Environmental Quality, 42(5): 1308-1326.

University of Maryland Extension. Manure Summary Report. Available at:

Ohio State Extension. Ohio Livestock Manure Management Guide. Bulletin 604. Available at:

Unconventionally Mining Phosphorus from Wastewater

By Michael Schmid of Renewable Nutrients

Conventional wastewater treatment facilities have evolved to become extremely proficient in the practice of sequestering nutrients, particularly phosphorus and nitrogen, present within their incoming municipal and industrial waste streams. Many facilities, and perhaps the case could be made to suggest “most” of the 16,000+ treatment plants in the United States, employ a form of chemical precipitation that serves to bind dissolved phosphorus to a metal salt or rare earth elements (e.g. – ferric chloride, alum or cerium chloride). This precipitations segregates the phosphorus such that it travels with the solids portion of the treatment process and thereby delivers to receiving waters a final liquid effluent that is low in phosphorus (or at least within a mandated tolerance for the nutrient).

The common practice of dosing an incoming waste stream with metal salts does have its disadvantages, however. In many cases, it can be rather costly just from a chemical consumption perspective, which is driven by the amount of daily incoming total phosphorus that needs to be isolated and removed from the liquid stream. The addition of metal salts also adds to the facility’s overall sludge content, creating more solids material that must be treated, digested, dewatered and ultimately disposed, and compounding the operational cost drivers that have to be controlled and managed. Finally, from an environmental standpoint, it simply cannot be beneficial long-term to landfill or even land apply biosolids that are artificially saturated with metals (and phosphorus), so beyond the daily cost of operations, there may very well prove to be a heavy cost to the environment.

Fortunately, many treatment facilities have recognized the operational and environmental costs associated with dosing metal salts and are employing alternatives. One emerging technology for managing incoming phosphorus, which has gained wide acceptance especially by progressive treatment plant operators, is bio-P. Here, phosphorus is captured and removed from the incoming liquid stream biologically by phosphorus accumulating organisms (PAOs). While bio-P can be very efficient at removing phosphorus and isolating it to the solids stream, the PAOs tend to release the nutrient from within their cell walls during and after anaerobic digestion. Unfortunately, this released phosphorus typically follows the liquid portion of the solid stream through dewatering, producing a high-P liquid side stream that is nearly always routed back to the plant’s head works, and must ultimately be re-treated again and again by the bio-P process. This side stream is commonly referred to as a “recycle stream,” and in many cases can exhibit phosphorus levels as high as or even exceeding 500ppm. Recycling this phosphorus-laden stream serves to limit the capacity and effectiveness of any bio-P process, yet it also yields a single, concentrated point or “reserve” from which phosphorus can be mined, recovered, and even re-used beneficially.

While academics and scientists have studied, debated, and preached about nutrient (and specifically phosphorus) recovery from waste streams for many years, putting the concept to practice is a relatively recent phenomenon. There are several new technologies on the market today that can assist a treatment facility in removing and recovering phosphorus from its waste streams, but one emerging technology that has proved particularly effective at recovering phosphorus from side streams or recycle flows is Quick Wash® – a concept originally developed by the USDA and commercialized by Renewable Nutrients.



Quick Wash is versatile enough that it can recover phosphorus from both liquid and solid streams, but given a bio-P operation (also sometimes referred to as Enhanced Biological Phosphorus Removal – EBPR), one area in particular where it can be effectively deployed is downstream of dewatering to treat the liquid side stream (or recycle stream). In the illustration above, the Quick Wash system receives the recycle flow and extracts nearly all of the phosphorus that is not already in solution. The system then precipitates out the phosphorus by introducing lime and forming calcium phosphate. The calcium phosphate is filtered using a liquid/solid separation apparatus and can be used beneficially as a phosphate fertilizer, an animal feed additive, or as a supply of raw material where calcium and phosphorus are required. The final liquid effluent from the Quick Wash system is routed back to the facility head works as a clean, very low-P or even no-P stream. So Quick Wash not only recovers phosphorus and produces a valuable byproduct, but it eliminates the recycle flow of phosphorus and yields greater capacity and efficiency in a bio-P operation. This increased capacity gives a facility the flexibility to increase its incoming waste stream flow without the addition of major infrastructure upgrades.

Progressive wastewater treatment facilities that operate bio-P combined with anaerobic digestion are producing an untapped, yet readily available phosphorus reserve in the form of phosphorus-rich recycle streams. Recycling released phosphorus from the solid stream back into the liquid stream only serves to add to a facility’s daily phosphorus load and create a scenario in which its bio-P operation is unable to operate at its intended capacity. The phosphorus-rich recycle streams of such facilities present an opportunity for technologies not only to extract and recover phosphorus and re-purpose it for beneficial re-use, but also to eliminate the constant recycling and re-treating of phosphorus within a treatment plant. Given a finite or limited worldwide phosphate rock supply, and the need for phosphorus as a life-sustaining nutrient important to preserving global food security, it only makes sense to “tap” the phosphorus reserve created in treatment plant recycle streams. Thanks to technologies, such as Quick Wash, phosphorus recovery may soon be standard operating procedure and wastewater treatment plants may very well be able to truly own and live-out the moniker “Water Resource Recovery Facility.”


Opinions expressed here do not necessarily reflect those of the Sustainable Phosphorus Alliance.

About Renewable Nutrients

Renewable Nutrients is a private, North Carolina-based company that turns waste into sustainable and profitable resources. Through its patented Quick Wash® system, Renewable Nutrients enables waste treatment facilities and animal feeding operations to extract and recover phosphorus from biosolids and manure. The remaining biosolids or manure, which contain crop-friendly ratios of nitrogen-to-phosphorus, can be land-applied, thus minimizing the amount of waste trucked to disposal sites, and reducing or even eliminating the incidence of nutrient pollution from soil runoff. In addition, municipalities and farms can sell the recovered phosphorus on the open market, and engage in the trading or marketing of nutrient credits.


Phosphorus Extraction from Wastes: The Key to Phosphorus Problems?

By Nick Reckinger of FEECO International, Inc.

As one of the key nutrients in growth, phosphorus is critical to maintaining food security and life on Earth. This has scientists worried over the dwindling mineralogical reserves from which we mine this valuable nutrient source. Interestingly, the world faces a problem of too much phosphorus in other areas; excess phosphorus from nutrient runoff is contaminating waterways and causing toxic algal blooms and dead zones throughout the world.

As the world looks to feed a growing population, demand for this life-giving nutrient is not likely to waver. This has many looking at the opportunity to use this resource in a more sustainable way. Processing of organic wastes can help alleviate pressure on finite resources while diverting phosphorus from waste as runoff back into the soil where it belongs.

The Case for Recycling Phosphorus

Organic wastes are a renewable resource, so it’s easy to see why the potential to derive even a small portion of our phosphorus requirements from this growing category of wastes is so attractive. One recent study looked at three primary phosphorus waste streams (human food waste, human excreta, and animal manure) and concluded that it would take only 37% of the phosphorus available in these existing waste streams to support the yearly U.S. corn crop’s phosphorus requirements.

Recycling phosphorus from organic wastes would not only provide the world with a much needed renewable source of phosphorus, but it would also help to mitigate the environmental problems that result from phosphorus runoff. Dead zones, or hypoxic areas that kill off fish and other organisms in waterways as a result of insufficient oxygen, have largely been blamed on nutrient runoff, with agriculture being a major contributing source.

Although restoration is an option, it is costly, making the prevention of dead zones much more feasible. And while there are many contributing factors to runoff (proximity to waterways, soil type, distance to bedrock, etc.), minimizing the potential for runoff to occur through proper fertilizing techniques and nutrient management best practices will likely be a primary endeavor in protecting waterways.

Two materials in particular have seen a surge of interest for their nutrient recovery and reuse potential: biosolids and manure.


Biosolids, also commonly called wastewater treatment sludge, are the materials left over from the wastewater treatment process. While various methods exist for the disposal of biosolids, disposal methods such as landfilling or incineration usually disregard the valuable nutrient content that biosolids hold. Additionally, disposal is increasingly being seen as unsustainable from a long-term perspective. And with increasing regulation around land application, municipalities are in need of a workable solution.


Similarly, regulation around the land application of manure has also been increasing, putting a growing strain on farms dealing with the massive amounts of manure produced by the agricultural norm of large-scale farming operations. Farms are also limited in the distance they can haul their manure to land apply it, due to its high moisture content, which makes transportation a costly expense.

Simultaneously, farms are purchasing chemical fertilizers to provide much of their nutrient needs, while the value of the manure they land apply is not often fully realized due to runoff, resulting in an inefficient imbalance of nutrient resources for crop production.

Granulation: Key to Recycling Phosphorus?

Phosphorus recovery from organic wastes is still in its infancy as an industry, with much research under way, and still more to be done. As a fertilizer industry veteran, we have been among those on the forefront of this issue, having developed process solutions and systems around nutrient recovery from organic wastes for decades. We use our expertise in granulation to transform difficult to handle, moisture-laden materials into a dry, premium-grade granular product that exceeds the EPA’s 503 regulations for a Class A Biosolid. This, in combination with significantly reduced odor, eases many of the issues surrounding land application.

In addition to these benefits and reduced transportation costs, there is ample opportunity for customized formulations and nutrient blends through granulation. As such, granulation can serve as a means to producing a marketable product that can supplement the purchase of additional nutrients for both municipalities and large-scale farms, all while reducing waste management costs.

Reduced Runoff through Granulation

While granulation offers many benefits to the farmer and/or municipality, the granulation of organic wastes into fertilizer or soil amendment products ultimately aids in the runoff prevention effort; because granulation produces a dry product, there is less potential for runoff to occur. Unlike the moisture-rich raw materials, a dry product does not add moisture to the soil, which can increase the likelihood of runoff occurring.

Furthermore, a granular product makes following a nutrient management program much easier and more efficient. The N:P ratio is often imbalanced as a result of fertilizing to meet nitrogen demands and inadvertently over-applying phosphorus. Granular products allow the N:P ratio to be carefully controlled to suit the nutrient profile of the land where it will be applied, significantly reducing the opportunity for runoff to occur. Granules also allow for easier and more accurate dispensing; soil receives only what it needs, further reducing the chance for excess phosphorus to leach from the soil.

An Overview of the Granulation Process

The granulation process is different from one source material to the next, with necessary pre-conditioning methods also differing. However, in general, granulation works by taking the nutrient-rich cake left over from the digestion process (or the wastewater treatment sludge remaining after the water treatment process), and mixing it in a pug mill.

Additives and/or nutrients can be included here to customize the formulation. The pug mill thoroughly mixes the feed materials (along with process recycle) to form agglomerates. These granules are then dried in a rotary dryer, where the tumbling action further rounds them. A cooling step reduces the temperature of the product, yielding a product that will hold up to handling and storage, but still deliver nutrients in a timely manner upon application.

As each source material differs in how it will respond to granulation, pilot testing is required to work out process variables and scale up the process to full-scale production.

FEECO Vice President and General Manager, Lee Hoffmann, who is also a member of the Brown County Phosphorus Committee, had this to say on the matter: “The importance of utilizing our organic wastes to their fullest potential is becoming increasingly critical as the world hosts a growing population. Add to that that some of our resources are essentially being wasted as runoff, and it’s easy to see why this approach makes sense. As a fertilizer industry veteran and an expert in the transformation of wastes into value-added products, we are well positioned to provide solutions to this market.”


Phosphorus is an invaluable nutrient to life on Earth. Maximizing available resources, while taking the pressure off of finite phosphate reserves is essential for long-term, sustainable phosphorus management.

Considering that renewable phosphorus resources in the form of manure and biosolids are often going to waste and even contributing to environmental issues, the potential these organic wastes hold to meet sustainable phosphorus goals is an incredibly valuable opportunity.


Opinions expressed here do not necessarily reflect those of the Sustainable Phosphorus Alliance.


FEECO provides feasibility testing, process and product design, and custom processing equipment for organic waste materials, including biosolids and manure. From idea, to complete process solution and custom equipment, FEECO offers capabilities in transforming organic wastes into value-added, marketable products. FEECO is based out of Green Bay, WI. In addition to their custom process equipment and systems, they offer a unique testing facility where they can conduct both batch and continuous, pilot-scale tests to simulate commercial production conditions.

Reclaiming the Value of Urine for Agriculture

By Tatiana Schreiber of the Rich Earth Institute

Abe Noe-Hays is a co-founder of Rich Earth Institute. The institute promotes collecting and using human urine as a plant fertilizer. Here Abe applies pasteurized urine to a test bed of lettuce. Photo by Marcin Szczepanski/Senior Multimedia Producer, University of Michigan, College of Engineering
Photo by Marcin Szczepanski

What is the potential for reclaiming the phosphorus present in human urine for agricultural use? World-wide there are a number of projects exploring this question, but few in the United States.[1] A small-scale but exciting example is the Rich Earth Institute’s Urine Nutrient Reclamation Project (UNRP) in Brattleboro Vermont.  Since 2012, Rich Earth has been collecting urine from 150 – 200 households in the community, transporting and sanitizing it, and using it as fertilizer on test fields of hay and vegetables. Rich Earth currently invites participants to save urine at home and bring it to a central depot. The long-term goal, however, is to support the wide-spread use of simple toilets and storage systems that can divert urine from aging sewage, storm water and water treatment systems, many of which are underperforming in cases of extreme weather events and changes in water cycles due to climate change.  Urine accounts for roughly three-quarters of the nitrogen and roughly half of the phosphorus in municipal waste streams. Research Director Abe Noe-Hays estimates that one thousand gallons of urine contains the equivalent of 109 pounds of urea, 13 pounds of triple superphosphate, and 29 pounds of muriate of potash (KCl), as well as smaller amounts of calcium, magnesium, sulfur and micronutrients Therefore, substituting urine for chemical fertilizers can be an appealing prospect depending on the nutrient needs of specific crops and the nutrient status of soils.

Rich Earth’s field tests on hay over several years have shown equivalent yields between urine-fertilized and chemically-fertilized test plots, both significantly higher than unfertilized plots. Forage quality remained high, and one farmer has been able to achieve a solid second cutting of hay where previously yields were not sufficient to warrant a second cutting.  Farmers participating in the project have had good results applying the sanitized urine to hayfields without dilution; one of Rich Earth’s goals is to develop a concentrated product that can be applied directly to reduce labor requirements. While it is likely the nitrogen rather than the phosphorus from urine is what has been the most significant nutrient in these Vermont test fields (because the soils were not deficient in phosphorus at the start), these experiments are an important model for the potential of recycling human waste for fertilizer world-wide.

Among hay and vegetable farmers in New England that Rich Earth has surveyed, interest in the potential of a urine-derived fertilizer is high, although farmers are cautious.  Respondents wrote, for example, “I think it is a great way to start closing the nutrient cycle – counting humans as part of the whole environmental web,” and “Could be a silver bullet; cost effective, renewable, recycling,” and “It’s about time we started using this valuable nutrient in the field instead of allowing it to contaminate drinking water by flushing it down the toilet.” Research suggests that farmers who currently practice organic or ecological methods may be more open to using urine than conventional farmers, but they may also have more concerns about potential contaminants in the urine including their impact on the health of soil biota. Not surprisingly, many also express concerns about how their customers may respond to the use of urine-derived fertilizers on their crops.

Rich Earth’s research aims to respond to some of these concerns. The organization will assess farmer interest and technical needs with regard to using these fertilizers on animal feed and fiber crops, perennial crops (such as fruit trees), ornamentals and other non-edible and edible crops. Testing indicates that heavy metal levels are extremely low – on average a thousand times below accepted risk levels. And although fiber, biomass, and animal feed crops could utilize all urine-derived fertilizer for the foreseeable future, Rich Earth has conducted field studies with lettuce and carrots to examine the fate of pharmaceuticals as well as biological components (viruses and bacteria) when urine-derived fertilizers are used for growing edible crops. Final results from this research have not yet been published, but the data so far indicate that while trace levels of pharmaceuticals could be detected in both lettuce and carrot tissue, the levels were very low. As Noe-Hays puts it, “a person would have to eat a salad from the study plot every day for two thousand years to get a single dose of acetaminophen (Tylenol).” With regard to bacteria and viruses, this research is ongoing, but current standards specify that urine can be effectively sanitized by pasteurization or by storing it from one to six months before using. Rich Earth’s ongoing research will help to better understand what happens under different storage and treatment practices.

With regard to public perceptions, Rich Earth’s social research seeks to learn more about what people know and think about what happens to their waste currently, and discover the most useful communication strategies to help attitudes evolve. In surveys and interviews with people who have contributed urine to the UNRP over the last four years, one important message stands out: people can and do change their attitudes over time. Although sometimes reluctant and uncomfortable at first, participants have become more and more enthusiastic about saving their urine and seeing it reused for agriculture. Learning about the value of urine as a fertilizer has inspired much of this evolution. For example, one person said, “I am so impressed by this simple process that turns a waste product into something so useful, saves water and avoids chemical fertilizers in our soil. Amazing! I love the environmental education that happens when curious visitors ask about that weird jug in our bathroom. It has started some good conversations!”

Of course there are no “weird jugs” when simple urine-diverting toilets are employed. Rich Earth is working towards more wide-spread use of these systems for source-separation and nutrient reclamation from urine, including addressing regulatory issues. Until now, human waste has been seen by regulatory agencies as something to be “disposed of” so as to protect public health.  But Rich Earth sees urine is a resource. Rather than needing to be “disposed of,” it should be collected and made use of as a “value-added” product. The organization currently has a permit for a mobile-pasteurizing unit through the Vermont Agency of Natural Resources’ Watershed Management Division. This has allowed local regulators to become comfortable with the concept of recycling urine for fertilizer. Using this permit, Rich Earth has developed the tools and equipment needed for larger scale processing of urine.

Ongoing research, now funded with a four-year grant through the National Science Foundation, will allow the organization to learn more about what regulators need to know and how best to communicate with them so that regulations can be written that will protect human health and the environment by keeping urine out of the waste stream and returning it to the soil.  Step by step, community by community, it will then become possible to close the loop and recycle the abundant nutrients, such as phosphorus, that we so generously expel in liquid form every single day.

Opinions expressed here do not necessarily reflect those of the Sustainable Phosphorus Alliance.

Tatiana Schreiber is an independent scholar with a doctorate in Environmental Anthropology. She teaches in the areas of agroecology, environmental studies and writing at Keene State College in New Hampshire and is a research associate at Rich Earth Institute. She also operates Sowing Peace Farm in Vermont, selling organic seedlings of heirloom and unusual varieties of vegetables and medicinal plants. Contact her at 


A New Technique for Studying Phosphorus Uptake in Plants

By Dr. Chad Penn

USDA-ARS, National Soil Erosion Research Laboratory

Studying the details of crop uptake of phosphorus (P) and other nutrients that have a strong affinity for minerals is very difficult in soils. Since plants take up nutrients from the solution phase and not directly from the soil, the use of soils in nutrient uptake experiments can be confounding.

Phosphorus must first be relinquished from the soil “warehouse” into solution before it can be taken up by a root. Therefore, nutrients in solution are potentially 100% bioavailable. To control solution concentrations is to control the root environment, and thus bioavailability. However, it is impossible to control solution P concentrations in the presence of soil because nutrients are dynamically sorbing from (i.e. adsorption, precipitation, and immobilization) and desorbing/dissolving/mineralizing into solution. The resolution to this experimental problem has been to utilize soil-less hydroponics, where the nutrients are 100% bioavailable as applied in the growing solution. While useful, it created another problem: hydroponic-grown plants are not similar to field-grown, especially with regard to roots. In addition, it is impossible to grow a realistic corn (maize) plant to maturity in such systems

Figure 1. Illustration of the dynamic between soil and solution-phase phosphorus (P): P must first be released by the soil into solution before it can be taken up by a plant.

Similarly, environmental conditions such as water availability, light, and temperature have a strong impact on nutrient uptake and vary dramatically in the field, making nutrient uptake experiments difficult to control and interpret. For this reason, many nutrient uptake experiments are conducted in greenhouses and growth chambers for environmental control. Still, both have some important disadvantages compared to field experiments; as a result, they do not produce plants that are similar to field-grown plants, making it difficult to practically apply the results of a nutrient study.

At the USDA-ARS National Soil Erosion Research Laboratory, we developed an indoor growth room, capable of growing 96 corn plants to maturity (R6) under fully artificial conditions with semi-automation. This system produces realistic maize plants with corresponding grain yields, thereby achieving all the benefits without the disadvantages of field, greenhouse, growth chamber, and traditional hydroponics studies, with regard to nutrient research.

After testing several non-soil media, we found that silica-sand was the best for two reasons: inertness and physical similarity to soil. With silica-sand, P (and all other nutrients) were neither sorbed or desorbed, allowing total control of the root environment and nutrient bioavailability. Nutrients were simply added with irrigation water. Figure 2 shows the major components of the growth-room.

Figure 2. Several components of the grow room. (a) Oscillating fan; (b) irrigation pipe containing drip emitters; (c) six rows of sloped trays for holding pots and draining water; (d) astronomical timer; (e) four rows of LED lights and power sources mounted on struts; (f) air duct for incoming air plus temperature, humidity, and CO2 sensors hanging from ceiling; (g) pulleys for raising/lowering LED lights; (h) controls for activating air handler and humidifiers; (i) air handler with filter located in “lung room” connected to air duct; (j) eight small nutrient injectors for applying treatments; (k) containers for treatment concentrate solution; (l) timer/controller for irrigation; (m) large nutrient injector for all non-treatment nutrients; (n) container for non-treatment nutrient concentrate; (o) drip emitter, one per pot; (p) humidifiers; (q) pots containing silica sand and drip rings; (r) mature and dry maize ready for harvest. Not shown: “Watch Dog” daily logger station for radiation, relative humidity and temperature, air conditioners, and louvers for exit air.

Nutrients were automatically dosed into irrigation water using nutrient injectors coupled with irrigation timers and solenoids. One single nutrient injector was used to inject all plant nutrients with the exception of the experimental nutrient, which in this case was P. After receiving non-P nutrients, the irrigation water was split into eight different nutrient injectors: one for each concentration of P to be tested. In addition to maintaining realistic diurnal variations in temperature and humidity, a changing photo-period was simulated with an astronomical timer which controlled LED lights. These lights produced a spectrum and intensity similar to the sun (unlike greenhouse lights) when maintained at a 16-inch distance from the plant. To achieve that, lights were attached to pulleys that allowed them to be raised upward as the plants grew. Sensors were used to monitor the atmosphere and trigger a whole-room ventilation system; all air entering the room was filtered to prevent any pests or disease. Oscillating fans were used to simulate the wind.

Compared to field-grown maize, maturity occurred earlier, likely due to more ideal growth conditions than what plants typically see in the field, including constant N addition and better weather. Plant parts and nutrient concentrations were nearly identical to field-grown corn. Plant growth was responsive to changes in P fertigation concentrations, illustrating the highly inert behavior of the silica sand growth media and the efficiency and bioavailability of the nutrient delivery system; that is what makes this system so valuable for conducting nutrient uptake and plant physiology studies. Based on a statistical analysis of the P study, maximum grain yield was achieved in this system with a P concentration of 7.8 mg/L, but total biomass continued to significantly increase with increasing P concentration until 14.4 mg/L, suggesting that genetic potential limited grain yield (Figure 3).

Figure 3. Grain (15.5% moisture content) and total biomass (dry basis) plant yield from harvested maize plants grown synthetically in the indoor grow room during a fertility trial. Values represent averages among three replications and three different hybrids grown using six different concentrations of P in fertigation (4, 8, 12, 15, 20, and 22 mg P L−1). Error bars indicate standard deviation.

Using this solution-culture methodology, plants can be grown with precise control of nutrient bioavailability due to the use of inert silica sand coupled with nutrient application in solution form, as demonstrated by its ability to not sorb any added P, whereas traditional hydroponics media were fairly sorptive. In practice, this means that the solution environment of plants could be altered within a matter of minutes in order to study the effects on plant physiological function and processes. This feature alone gives this solution-culture method immense potential for plant nutrient timing studies. Growing plants in this type of artificial environment has immediate applications for nutrient and physiological studies. The system described also allows for precise manipulation of light, specifically light intensity, quality, and photoperiod duration. Additionally, one of the most important features of this growth environment is that regardless of study type, a relatively large number of plants (96 in this instance) can be grown and observed at one time. In theory, this number could be scaled up where there is adequate space. For more details, please see Weithorn et al. (2021).


Abendroth, L.J.; Elmore, R.W.; Boyer, M.J.; Marlay, S.K. Corn Growth and Development; Iowa State University Extension Publication PMR1009: Ames, IA, USA, 2011.

Wiethorn, M., Penn, C., and Camberato, J. (2021). A Research Method for Semi-Automated Large-Scale Cultivation of Maize to Full Maturity in an Artificial Environment. Agronomy, 11(10), 1898. Online at:

Opinions expressed here do not necessarily reflect those of the Sustainable Phosphorus Alliance.


Featured Member: GreenTechnologies

Green Edge logo

Florida-based GreenTechnologies creates environmentally sound lawn and landscape solutions for personal, commercial and public interests. They develop products from renewable resources, for advancement of nutrient recycling and improving environmental quality.

How big is your company and where does it operate?

GreenTechnologies is a small Florida based Company with national product distribution network.

What does your company do related to phosphorus sustainability?

GreenTechnologies has developed patented process for production of Biobased Slow Release GreenEdge fertilizers. The phosphorus in our products is 100% renewable and it is recovered from wastewater treatment process. We have recovered and utilized more than 20,000,000 pounds of this renewable phosphorus for commercial turfgrass and other landscape plants. In addition to the phosphorus, we have also recovered and upcycled more than 60,000,000 pounds of nitrogen, and more than 350,000,000 pounds of organic matter.

What’s your business model?

Our business model is to provide our technology to wastewater treatment facilities for production of biobased fertilizers. We can also provide distribution and marketing of the products.

What are the biggest challenges you face?

The biggest challenge is the slow process of large scale project development.

Where do you see the biggest opportunities for advancing phosphorus sustainability?

Continued population growth worldwide provides significant opportunities for wastewater treatment and phosphorus recovery and utilization.

What’s been your biggest sustainability win?

Our biggest sustainability win has been our ability to produce the GreenEdge Biobased products cost effectively and developing a diverse customer base.

Featured Member: NACWA

NACWA logo

DC-based NACWA is a founding member of the Sustainable Phosphorus Alliance, and its Deputy CEO, Chris Hornback, serves on our Board of Directors.

Where does your organization operate and what is your business model?

National Association of Clean Water Agencies (NACWA) is the nation’s recognized leader in legislative, regulatory, legal and communications advocacy on the full spectrum of clean water issues. NACWA represents public wastewater and stormwater agencies of all sizes nationwide. Our vision is to advance sustainable and responsible policy initiatives that help to shape a strong and sustainable clean water future.

What are the biggest challenges you face?

Currently, we are working to secure tens of billions of dollars in federal funding to match the growing need to upgrade America’s increasingly out-of-date water infrastructure. Addressing the growing water affordability crisis, securing increased funding to the Clean Water State Revolving Fund, and working to ensure Clean Water Act regulatory policies reflect a net environmental benefit approach are some key challenges our sector faces.

Where do you see the biggest opportunities for advancing phosphorus sustainability?

As addressed in President Biden’s American Jobs Act, a total replacement of lead service lines would render moot the orthophosphate paradox. If lead service lines are replaced, there is no need to mandate orthophosphate as the must-use optimal corrosion control technique.

What’s been your biggest sustainability win?

Staying with the orthophosphate issue, Denver Water, understanding the downstream nutrient impacts to Denver Metropolitan Reclamation District, is deviating from a mandated orthophosphate dosing and is proposing a “Lead Reduction Program Plan.” This innovative and funded approach, in collaboration with various environmental groups, will replace the estimated 75,000 lead service lines in 15 years. More information here.

To Dose, or Not to Dose? The Orthophosphate Paradox

By Emily Remmel, Director of Regulatory Affairs, NACWA

Emily Remmel

In the wake of the public health crisis that unfolded (and continues to unfold) in Flint, Michigan, EPA is critically thinking about how to modernize the Lead and Copper Rule (LCR) framework both in terms of protecting public exposure to lead in drinking water as well as the manner of replacing the thousands of lead service lines buried across the country. The U.S. Environmental Protection Agency’s (EPA) continues to slog through the process of revising and updating the three-decade-old LCR.

Under the previous Administration, EPA penned a final rule and published it in the Federal Register on January 15, 2021 that established effective dates and future compliance dates for drinking water systems. This updated LCR seemed to be a done deal; however, the Biden-Harris Administration—through a “regulatory freeze”—pulled the rule back for a closer review and to potentially revise the rule yet again.

The current quasi political-regulatory review mainly involves the concerns of drinking water systems and the Safe Drinking Water Act. However, a lesser-known issue—the mandating of orthophosphorus as a standardized, national optimal corrosion control treatment (OCCT) method—has unearthed serious Clean Water Act concerns within the clean water community.

Traditionally, public water systems have been granted inherent flexibility under the Safe Drinking Water Act to select the corrosion control technology that would be most effective at mitigating lead leaching from aging pipes based on local water quality parameters. In a true one-water framework, upstream drinking water utilities should be able to consider and make flexible management decisions that are protective of public health as well as protective of downstream water quality.

The Agency, in its 2020 proposed rule, stated “the use of orthophosphate for corrosion control can increase phosphorus loading to wastewater treatment facilities… (which) may be a concern for wastewater systems with phosphorus discharge limits or for systems that discharge into water bodies where phosphorus is a limiting nutrient” (84 Fed. Reg. 61693). Yet, EPA also restricts drinking water systems from considering their downstream wastewater treatment neighbors’ potential increased cost impacts or water quality degradation, stating, “water systems conducting corrosion control studies would not be able to rule out orthophosphate simply based on the increase in loading to wastewater treatment facilities.”

The required use of orthophosphate will undoubtedly require downstream wastewater treatment plants to treat effluent to greater levels at greater costs in order to comply with stringent Clean Water Act nutrient requirements. This will be particularly true of those wastewater treatment plants in arid and semi-arid areas where clean water utilities discharge into low flow or effluent dominated streams.

Upon review, EPA should address this nutrient paradox. Nutrient pollution is a known driver for surface water quality degradation, and many communities are witnessing an increase in eutrophication, algal blooms, and subsequent hypoxic zones due to excess phosphorus and nitrogen from point and nonpoint sources contributions.

Now that EPA is taking a harder look at the LCR, the clean water community urges the Agency to recognize this critical regulatory issue through the lens of a holistic, one water approach that transects both the Safe Drinking Water Act and the Clean Water Act.

EPA could reinstate the inherent flexibilities traditionally granted to drinking water utilities to determine through best professional judgment the right OCCT on a case by case basis. Alternatively, it could encourage state regulatory authorities to provide downstream clean water utilities with Clean Water Act regulatory flexibility. For example, it could encourage them to consider the development of a variance or conducting a use attainability analysis (UAA) to account for increased phosphorus concentrations associated with the LCR, where necessary to enable utilities to meet Clean Water Act permitting requirements.

It is possible to provide critical public health protections through drinking water treatment without sacrificing downstream environmental and water quality. EPA has a unique opportunity as it reviews the LCR in closer detail to acknowledge and promote a one-water framework for both drinking water and clean water utilities in their efforts as public health protectors and environmental stewards.


Opinions expressed here do not necessarily reflect those of the Sustainable Phosphorus Alliance.


National Association of Clean Water Agencies (NACWA) is the nation’s recognized leader in legislative, regulatory, legal and communications advocacy on the full spectrum of clean water issues. NACWA represents public wastewater and stormwater agencies of all sizes nationwide. Our vision is to advance sustainable and responsible policy initiatives that help to shape a strong and sustainable clean water future.