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

Authors

A. Schlegel, Kansas State UniversityFollow
H. D. Bond, Kansas State UniversityFollow

Keywords

nitrogen fertilization, phosphorus fertilization, irrigated grain sorghum, long-term fertility, nutrient removal

Abstract

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 applied alone increased yields 60 bu/a, whereas N and P applied together increased yields up to 83 bu/a. Averaged across the past 10 years, N and P fertilization increased sorghum yields up to 82 bu/a. The application of 160 lb/a N (with P) produced the maximum yield in 2020, which is slightly less than the 10-year average (2011–2020). The application of potassium (K) has had no effect on sorghum yield throughout the study period. The 10-year average grain N content reached a maximum of ~0.7 lb/bu while grain P content reached a maximum of ~0.15 lb/bu (0.34 lb P₂O₅/bu) and grain K content reached a maximum of ~0.19 lb/bu (0.23 lb K₂O/bu). At the highest N, P, and K rate, apparent fertilizer recovery in the grain was 33% for N, 69% for P, and 40% for K.

Recommended Citation

Schlegel, A. and Bond, H. D. (2021) "Long-Term Nitrogen, Phosphorus, and Potassium Fertilization of Irrigated Grain Sorghum," Kansas Agricultural Experiment Station Research Reports: Vol. 7: Iss. 8. https://doi.org/10.4148/2378-5977.8123