Weather and soil in the US Midwest influence the effectiveness of single‐ and split‐nitrogen applications in corn production
Jason D. Clark, Fabián G. Fernández, James J. Camberato, Paul R. Carter, Richard B. Ferguson, David W. Franzen, Newell R. Kitchen, Carrie A. M. Laboski, Emerson D. Nafziger, John E. Sawyer, John F. Shanahan
Abstract
Abstract Splitting the N application into two or more timings may improve corn ( Zea mays L.) grain yield and N recovery relative to a single‐N application. A 49 site‐year study across eight U.S. Midwestern states compared the effect of an at‐planting (single‐N application) and two split‐N applications [45 (45+SD) or 90 kg N ha −1 (90+SD) at planting with the remainder of the total rate (180 or 270 kg N ha −1 ) applied at V9]. For split‐N applications, soil and plant responses were similar between 45+SD and 90+SD 93–98% of the time, indicating the at‐planting N rate of 45 kg N ha −1 may be all that is needed in most cropping scenarios. Splitting the N application compared to a single‐N application changed soil NO 3 –N at VT and post‐harvest <35% of the time and plant N uptake and grain yield <15% of the time. Split‐N applications had greater grain yield in areas with uniform precipitation around the sidedress timing (Shannon Diversity Index >0.56–0.59) to incorporate N in the root zone, and in coarse‐textured soil (sand content >4–10%) that had greater potential for N loss. Single‐N applications produced greater grain yield in soils with more total N (>2.1–2.4 g kg −1 ) to support N mineralization and greater cation exchange capacity (CEC) (> 27–31 cmol c kg −1 ), silt content (>66–74%), or clay content (>24–37%) to improve nutrient and water retention. Decisions on nitrogen application timing should be made based on soil parameters and typical weather conditions around the sidedress timing.