106688 Sufficiency Level Vs. Build and Maintain Approaches to Managing Phosphorus for Crop Production.
Poster Number 931
Wednesday, October 25, 2017
Tampa Convention Center, East Exhibit Hall
Phosphorus fertilizer management in Minnesota is based on one of two philosophical approaches, Build and Maintain (B&M) and Sufficiency. Long-term experiments were established at six sites across Minnesota. At each site, four soil test P (STP) Interpretation Classes of Low, Medium, High, and Very High were established over a four-year period. Each STP class was split into two split-plots: one received no additional P fertilizer, and the other received 168, 101, 34 and 34 kg P2O5 ha-1 in the Low, Medium, High, and Very High class, respectively. Corn grain yield and grain P removal were determined during 2015 and 2016 growing season. Overall, 2 of the 6 sites showed significant response to applied-P only in the Low and Medium soil classification classes (Becker, Crookston) in 2015. During 2016 growing season 3 of the 6 sites showed significant response to applied-P only in the Low and/or Medium STP classes (Becker, Crookston,Waseca). Grain P removal was more responsive in both growing seasons, and 4 of the 6 sites showed greater P removal with applied-P especially in the Low and Medium classification classes. The greatest response to fertilizer P was in the Low and Medium STP classes as expected. There was little to no response to applied P in the High or Very High STP classes. In both growing season, there was no evidence at any of the sites that building and maintaining a high soil test level had a greater grain yield potential than applying P fertilizer annually based on soil test level regardless what that level was. The Sufficiency Approach was just as productive with P fertilizer applied to Low or Medium soil testing P soils as higher testing P soils with or without P fertilizer applied.