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

Authors

A. J. 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 2018, N applied alone increased yields 44 bu/a, whereas N and P applied together increased yields up to 67 bu/a. Averaged across the past 10 years, N and P fertilization increased sorghum yields up to 75 bu/a. Application of 80 lb/a N (with P) produced the maximum yield in 2018, which is slightly less than the 10-year 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 31% for N, 65% for P, and 38% for K.

Recommended Citation

Schlegel, A. J. and Bond, H. D. (2019) "Long-Term Nitrogen, Phosphorus, and Potassium Fertilization of Irrigated Grain Sorghum," Kansas Agricultural Experiment Station Research Reports: Vol. 5: Iss. 4. https://doi.org/10.4148/2378-5977.7753