Soybean potassium nutrition and yield are enhanced by a short‐term poultry litter fertilization history in a corn–cotton–soybean rotation system

Whether poultry litter (PL) applied to preceding crops benefits subsequent soybean crops is poorly understood. The objective of this study was to determine whether a short history of PL and crop rotation maintains or enhances soybean yield in subsequent years without fertilizers. The study was a continuation of a 5‐year study in which five fertilization treatments were imposed on four crop rotation treatments in a factorial combination. The crop rotation history included combinations of corn, cotton, and soybean. The five fertility treatments included a no fertilizer control (UTC), a synthetic fertilizer treatment (Std); PL application based on P need for 5 years (P5L) and N need for 5 years (N5L) or 2 years (N2L) in 2010–2014. In 2015–2018, soybean was grown in the field yearly with no fertilization for P5L, N5L, N2L, and the UTC and with recommended fertilizers for the Std. The results showed, relative to the Std, the N5L treatment in the subsequent 4 years increased soybean leaf K by 24.4%, reduced leaf Mn by 22.2%, and increased seed yield by 12.4%. The P5L and N2L treatments also enhanced yield and leaf nutrition but by a smaller magnitude. These enhancement effects lasted 4–7 years. Crop rotation history only mildly affected soybean yield. The results overall show that a 2‐ to 5‐year PL application history to fertilize previous rotational crops enhances soybean yield beyond that possible with conventional practices for 4–7 years after the last application by enhancing K nutrition and reducing tissue Mn concentration.