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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.