Fertility
Long-Term Nitrogen, Phosphorus and Potassium Fertilization of Irrigated Grain Sorghum
A. Schlegel and H. D. Bond
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. Nitrogen fertilization increased soil organic matter and decreased soil pH. Phosphorus fertilization tended to maintain or increase soil test P levels.
Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Corn
A. Schlegel and H. D. Bond
Abstract: Long-term research shows that phosphorus (P) and nitrogen (N) fertilizer must be applied to optimize production of irrigated corn in western Kansas. In 2020, N applied alone increased yields by 85 bu/a, whereas P applied alone increased yields 10 bu/a. Nitrogen and P applied together increased yields up to 136 bu/a which is 11 bu/a less than the 10-year average of 147 bu/a. The application of 120 lb N/a (with highest P rate) produced 98% of maximum yield in 2020, which is greater than the 10-year average (2011–2020). The application of 80 instead of 40 lb P2O5/a increased average yields 1 bu/a. The 10-year average grain N content reached a maximum of 0.6 lb/bu while grain P content reached a maximum of 0.15 lb/bu (0.34 lb P2O5/bu). At the highest N and P rate, apparent fertilizer nitrogen recovery in the grain (AFNRg) was 43% and apparent fertilizer phosphorus recovery in the grain (AFPRg) was 63%. Nitrogen fertilization increased soil organic matter and decreased soil pH. Phosphorus fertilization at 40 lb/a P2O5 was not sufficient to maintain soil test levels.
Related Publications
Schlegel, A.J. and J. L. Havlin. 2020. Irrigated grain sorghum response to 55 years of nitrogen, phosphorus, and potassium fertilization. Agron. J. n/a:n/a. DOI:10.1002/agj2.20453
Obour, A.K., A.J. Schlegel, R. Perumal, J.D. Holman, D. Ruiz Diaz. 2019. Evaluating grain sorghum hybrids for tolerance to iron chlorosis. J. Plant Nutrition. DOI:10.1080/01904167.2018.1549677
Schlegel, A.J., Y. Assefa, H.D. Bond, L.A. Haag, and L.R. Stone. 2017. Changes in soil nutrients after 10 years of cattle manure and swine effluent application. Soil Tillage Res. 172:48-58. DOI: 10.1016/j.still.2017.05.004
Schlegel, A.J. and J.L. Havlin. 2017. Corn yield and grain nutrient uptake from 50 years of nitrogen and phosphorus fertilization. Agron. J. 109:335-342. DOI: 10.2134/agronj2016.05.0294
Schlegel, A.J., Y. Assefa, H.D. Bond, S.M. Wetter, and L.R. Stone. 2015. Corn response to long-term applications of cattle manure, swine effluent, and inorganic N fertilizer. Agron. J. 1701-1710. DOI: 10.2134/agronj14.0632
Schlegel, A.J., Y. Assefa, H.D. Bond, S.M. Wetter, and L.R. Stone. 2015. Soil physicochemical properties after 10 years of animal waste application. Soil Sci. Soc. Am. J. 79:711-719. DOI: 10.2136/sssaj2014.11.0461
Sohm, G., C.R, Thompson, Y. Assefa, A.J. Schlegel, and J. Holman. 2014. Yield and quality of bermudagrass as a function of nitrogen rate. Agron. J. 106:1489-1496
