Subsurface drainage and nitrogen management affects corn and soybean yield in claypan soils in upstate Missouri

Nitrogen (N) and subsurface drainage water management are crucial and challenging components of sustainable crop production on poorly drained claypan soils. During extreme precipitation events, N fertilizer management is difficult in a corn (Zea mays L.)-soybean (Glycine max L.) rotation that balances productivity and environmental quality. This 4-year (2018-2021) experiment was conducted on a poorly drained soil to examine the interactive effects of drainage (subsurface tile drainage [SD] and no drainage [ND]) and corn N fertilizer treatments (non-treated control [NTC], fall-applied anhydrous ammonia [AA] at 190 kg N ha(-1) with nitrapyrin [fall AA + NI], pre-plant AA [spring AA] at 190 kg N ha(-1), and top-dressed urea [TD urea] as 42 kg N ha(-1) SuperU and 126 kg N ha(-1) ESN as a 25:75% granular blend) on yield and nutrient uptake. Corn grain yield was 1.22-1.53 Mg ha(-1) greater with fertilizer treatments in SD compared to ND. Drought conditions in 2018 lowered corn grain yield compared to 2020. Average over 2 years, corn yield in SD soils was ranked as spring AA > fall AA + NI > TD urea > NTC. While soybean yield following corn was 13% greater in the NTC compared to TD urea. The SD treatment increased soybean yield by 0.6-2 Mg ha(-1) compared to ND. This study results showed that fall AA + NI produced corn yields similar to spring AA in SD and ND soils in temperate humid climatic conditions.