Fifteen Years of Wheat Yield, N Uptake, and Soil Nitrate-N Dynamics in a Biosolids-Amended Agroecosystem. Agriculture, Ecosystems and Environment

Understanding N dynamics in biosolids-amended agroecosystems can help avoid over-application and the potential for environmental degradation. We investigated 15-years of biosolids application to dryland-wheat, questioning what is the relationship between cumulative grain yield and N uptake (N removal) and biosolids or N fertilizer rates and how many times biosolids or N fertilizer are applied? How are wheat-grain production and N uptake intertwined with residual soil nitrate-N? We found that biosolids or N fertilizer rates plus the number of applications of each material produced planar-regression (3-dimensional) models with 15-years of grain yield and N uptake data (all R2 > 0.93). To evaluate how yield or N uptake impacted residual soil nitrate-N, we completed linear regressions on yield, N uptake, and soil nitrate-N. We then correlated the slopes where P