Irrigated Grain Sorghum Response to Long-Term Nitrogen, Phosphorus, and Potassium Fertilization

Long-term research shows that phosphorus (P) and nitrogen (N) fertilizer must be applied to optimize production of irrigated grain sorghum in western Kansas. In 2020, N alone increased yields 60 bu/a, whereas P together up 83 bu/a. Averaged across the past 10 years, fertilization 82 The application 160 lb/a (with P) produced maximum yield which is slightly less than 10-year average (2011–2020). potassium (K) has had no effect on throughout study period. content reached a ~0.7 lb/bu while 0.15 (0.34 lb P2O5/bu) K 0.19 (0.23 K2O/bu). At highest N, P, rate, apparent recovery was 33% for 69% 40% K. Nitrogen soil organic matter decreased pH. Phosphorus tended maintain or increase test levels.