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
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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.
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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)