Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum

Kansas Agricultural Experiment Station Research Reports, Feb 2015

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 2014, N applied alone increased yields 49 bu/a, whereas N and P applied together increased yields up to 81 bu/a. Averaged across the past 10 years, N and P fertilization increased sorghum yields up to 73 bu/a. Application of 40 lb/a N (with P) was sufficient to produce more than 80% of maximum yield in 2014, which almost equals the 10-year average. Application of potassium (K) has had no effect on sorghum yield throughout the study period.

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Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum

Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum A. Schlegel 0 1 H. D. Bond 0 1 0 Kansas State University , USA 1 Part of the Agricultural Science Commons , Agriculture Commons, and the Agronomy and Crop Follow this and additional works at: https://newprairiepress.org/kaesrr Sciences Commons Recommended Citation Schlegel, A. and Bond, H. D. (2015) "Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum," Kansas Agricultural Experiment Station Research Reports: Vol. 1: Iss. 3. https://doi.org/10.4148/2378-5977.1028 - This report is brought to you for free and open access by New Prairie Press. It has been accepted for inclusion in Kansas Agricultural Experiment Station Research Reports by an authorized administrator of New Prairie Press. Copyright January 2015 Kansas State University Agricultural Experiment Station and Cooperative Extension Service. Contents of this publication may be freely reproduced for educational purposes. All other rights reserved. Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned. K-State Research and Extension is an equal opportunity provider and employer. Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum 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 2014, N applied alone increased yields 49 bu/a, whereas N and P applied together increased yields up to 81 bu/a. Averaged across the past 10 years, N and P fertilization increased sorghum yields up to 73 bu/a. Application of 40 lb/a N (with P) was sufficient to produce more than 80% of maximum yield in 2014, which almost equals the 10-year average. Application of potassium (K) has had no effect on sorghum yield throughout the study period. Creative Commons License This work is licensed under a Creative Commons Attribution 4.0 License. This Southwest Research-Extension Center article is available in Kansas Agricultural Experiment Station Research Reports: https://newprairiepress.org/kaesrr/vol1/iss3/6 Kansas Fertilizer Research 2015 Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum Summary 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 2014, N applied alone increased yields 49 bu/a, whereas N and P applied together increased yields up to 81 bu/a. Averaged across the past 10 years, N and P fertilization increased sorghum yields up to 73 bu/a. Application of 40 lb/a N (with P) was sufficient to produce more than 80% of maximum yield in 2014, which almost equals the 10-year average. Application of potassium (K) has had no effect on sorghum yield throughout the study period. Introduction This study was initiated in 1961 to determine responses of continuous grain sorghum grown under flood irrigation to N, P, and K fertilization. The study is conducted on a Ulysses silt loam soil with an inherently high K content. The irrigation system was changed from flood to sprinkler in 2001. Procedures This field study is conducted at the Tribune Unit of the Southwest Research-Extension Center. Fertilizer treatments initiated in 1961 are N rates of 0, 40, 80, 120, 160, and 200 lb/a N without P and K; with 40 lb/a P2O5 and zero K; and with 40 lb/a P2O5 and 40 lb/a K2O. All fertilizers are broadcast by hand in the spring and incorporated before planting. The soil is a Ulysses silt loam. Sorghum (Pioneer 8500/8505 from 2003– 2007, Pioneer 85G46 in 2008–2011, and Pioneer 84G62 in 2012–2014) was planted in late May or early June. Irrigation is used to minimize water stress. Sprinkler irrigation has been used since 2001. The center two rows of each plot are machine harvested after physiological maturity. Grain yields are adjusted to 12.5% moisture. Results Grain sorghum yields in 2014 were 18% greater than the 10-year average (Table 1). Nitrogen alone increased yields 49 bu/a, whereas P alone increased yields only 4 bu/a. However, N and P applied together increased yields up to 81 bu/a. Averaged across the past 10 years, N and P applied together increased yields up to 73 bu/a. In 2014, 40 lb/a N (with P) produced about 82% of maximum yield, which almost equals the 10-year average of 83%; 120 lb/a N (with P) and 160 lb/a N (with P) produced 92% and 97% of maximum yield, respectively. Sorghum yields were not affected by K fertilization, which has been the case throughout the study period. 73 88 87 LSD(0.05) 7 1 2005 yields used only blocks 3, 4, and 5. 77 112 126 129 134 135 6 (...truncated)


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A. Schlegel, H. D. Bond. Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum, Kansas Agricultural Experiment Station Research Reports, 2015, Volume 1, Issue 3,