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

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 2016, N applied alone increased yields 71 bu/a, whereas N and P applied together increased yields up to 93 bu/a. Averaged across the past 10 years, N and P fertilization increased sorghum yields up to 77 bu/a. Application of 80 lb/a N (with P) was sufficient to produce 89% of maximum yield in 2016, which is slightly less than the 10-yr average. Application of potassium (K) has had no effect on sorghum yield throughout the study period. 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. (2017) "Irrigated Grain Sorghum Response to Long-Term Nitrogen and Phosphorus Fertilization," Kansas Agricultural Experiment Station Research Reports: Vol. 3: Iss. 5. https://doi.org/10.4148/2378-5977.7402