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 2015, N applied alone increased yields 66 bu/a, whereas N and P applied together increased yields up to 92 bu/a. Averaged across the past 10 years, N and P fertilization increased sorghum yields up to 76 bu/a. Application of 40 lb/a N (with P) was sufficient to pro­duce 88% of maximum yield in 2015 which is slightly above 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)

Bond, H. D.

Schlegel, A.

English

Kansas State University

Kansas Agricultural Experiment Station Research Reports Volume 2 Issue 7 Southwest Research-Extension Center Reports Article 17 January 2016 Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum A. Schlegel Kansas State University, schlegel@ksu.edu H. D. Bond Kansas State University, dbond@ksu.edu 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 2016 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. Follow this and additional works at: https://newprairiepress.org/kaesrr  Part of the Agronomy and Crop Sciences Commons Recommended Citation Schlegel, A. and Bond, H. D. (2016) "Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum," Kansas Agricultural Experiment Station Research Reports: Vol. 2: Iss. 7. https://doi.org/10.4148/2378-5977.1262 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 2015, N applied alone increased yields 66 bu/a, whereas N and P applied together increased yields up to 92 bu/a. Averaged across the past 10 years, N and P fertilization increased sorghum yields up to 76 bu/a. Application of 40 lb/a N (with P) was sufficient to produce 88% of maximum yield in 2015 which is slightly above 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). Keywords nitrogen, phosphorus, irrigated grain sorghum Creative Commons License This work is licensed under a Creative Commons Attribution 4.0 License. This soil fertility is available in Kansas Agricultural Experiment Station Research Reports: https://newprairiepress.org/kaesrr/vol2/iss7/17 2016 SWRECAgricultural ResearchKansas State University Agricultural Experiment Station and Cooperative Extension Service1Nitrogen and Phosphorus Fertilization  of Irrigated Grain SorghumA. Schlegel and H.D. BondSummaryLong-term research shows that phosphorus (P) and nitrogen (N) fertilizer must be applied to optimize production of irrigated grain sorghum in western Kansas. In 2015, N applied alone increased yields 66 bu/a, whereas N and P applied together increased yields up to 92 bu/a. Averaged across the past 10 years, N and P fertilization increased sorghum yields up to 76 bu/a. Application of 40 lb/a N (with P) was sufficient to pro-duce 88% of maximum yield in 2015 which is slightly above the 10-yr average. Applica-tion 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).IntroductionThis 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.ProceduresThis 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 2006–2007, Pioneer 85G46 in 2008–2011, Pioneer 84G62 in 2012-2014, and Pioneer 86G32 in 2015) 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. Grain samples were collected at harvest, dried, ground, and analyzed for N, P, and K concentrations. Grain N, P, and K content (lb/bu) and removal (lb/a) were calculated.Results and DiscussionGrain sorghum yields in 2015 were 22% greater than the 10-year average (Table 1). Ni-trogen alone increased yields 66 bu/a while P alone increased yields 13 bu/a. However, Kansas State University Agricultural Experiment Station and Cooperative Extension Service22016 SWREC Agricultural ResearchN and P applied together increased yields up to 92 bu/a. Averaged across the past 10 years, N and P applied together increased yields up to 76 bu/a. In 2015, 40 lb/a N (with P) produced about 88% of maximum yield, which is slightly above the 10-year aver-age of 84%; 120 lb/a N (with P) and 160 lb/a N (with P) produced 98% and 100% of maximum yield, respectively. Sorghum yields were not affected by K fertilization, which has been the case throughout the study period.  The 10-year average grain N concentration (%) increased with N rates but tended to decrease when P was also applied, presumably because of higher grain yields diluting N content (Table 2). Grain N content reached a maximum of ~0.7 lb/bu. Maximum N removal (lb/a) was obtained with 160 lb N/a or greater with P. Similar to N, average P concentration increased with P application but decreased with higher N rates. Grain P content (lb/bu) of ~0.15 lb P/bu (0.34 lb P2O5/bu) was similar for all N rates when P was applied. Grain P removal was similar for all N rates of 40 lb/a or greater with P applications ranging from 19 to 23 lb/a. Average K concentration (%) and content (lb/bu) tended to decrease with increased N rates. Similar to P, K removal was similar for all N rates of 40 lb/a or greater plus K ranging from 23 to 27 lb/a.Kansas State University Agricultural Experiment Station and Cooperative Extension Service32016 SWREC Agricultural ResearchTable 1. Nitrogen, phosphorus, and potassium fertilizers on irrigated grain sorghum yields, Tribune, KS, 2006-2015.Fertilizer Grain sorghum yieldN P2O5 K2O 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Mean------------ lb/a ------------ --------------------------------------------------- bu/a ---------------------------------------------------0 0 0 84 80 66 64 51 75 78 62 90 89 740 40 0 102 97 60 70 51 83 90 77 94 102 830 40 40 95 94 65 76 55 88 93 72 96 97 8340 0 0 102 123 92 84 66 106 115 94 115 122 10240 40 0 133 146 111 118 77 121 140 114 144 160 12640 40 40 130 145 105 109 73 125 132 110 142 155 12380 0 0 111 138 114 115 73 117 132 102 120 133 11680 40 0 132 159 128 136 86 140 163 136 151 173 14080 40 40 142 166 126 108 84 138 161 133 164 178 140120 0 0 101 138 106 113 70 116 130 100 116 127 112120 40 0 136 164 131 130 88 145 172 137 162 177 144120 40 40 139 165 136 136 90 147 175 142 170 178 148160 0 0 123 146 105 108 74 124 149 117 139 150 123160 40 0 145 170 138 128 92 152 178 146 171 181 150160 40 40 128 167 133 140 88 151 174 143 176 179 148200 0 0 134 154 120 110 78 128 147 119 139 155 128200 40 0 143 168 137 139 84 141 171 136 165 177 146200 40 40 143 170 135 129 87 152 175 138 170 179 148continuedKansas State University Agricultural Experiment Station and Cooperative Extension Service42016 SWREC Agricultural ResearchTable 1. Nitrogen, phosphorus, and potassium fertilizers on irrigated grain sorghum yields, Tribune, KS, 2006-2015.Fertilizer Grain sorghum yieldN P2O5 K2O 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Mean------------ lb/a ------------ --------------------------------------------------- bu/a ---------------------------------------------------ANOVA(P>F)Nitrogen 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001Linear 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001Quadratic 0.004 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001P-K 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001Zero P vs. P 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001P vs. P-K 0.578 0.992 0.745 0.324 0.892 0.278 0.826 0.644 0.117 0.806 0.951N × P-K 0.210 0.965 0.005 0.053 0.229 0.542 0.186 0.079 0.012 0.002 0.035MEANSNitrogen,lb/a0 93d 91d 64d 70c 52c 82d 87d 70d 94e 96d 80d40 121c 138c 103c 104b 72b 117c 129c 106c 134d 146c 117c80 128bc 155b 123b 120a 81a 132b 152b 124b 145c 161b 132b120 125bc 156ab 124ab 126a 82a 136ab 159ab 126b 149bc 161b 134b160 132ab 161ab 125ab 125a 84a 142a 167a 135a 162a 170a 140a200 140a 164a 131a 126a 83a 141a 165a 131ab 158ab 170a 141aLSD(0.05) 11 9 7 11 5 8 9 8 9 8 6P2O5,lb/a0 109b 130b 101b 99b 68b 111b 125b 99b 120b 129b 109b40 132a 151a 117a 120a 80a 130a 152a 124a 148a 162a 132a80 130a 151a 117a 116a 79a 133a 152a 123a 153a 161a 132aLSD(0.05) 7 6 5 7 4 6 6 5 6 5 4Kansas State University Agricultural Experiment Station and Cooperative Extension Service52016 SWREC Agricultural ResearchTable 2. Nitrogen, phosphorus, and potassium fertilizers on grain N, P, and K content of irrigated grain sorghum, Tribune, KS, 2006-2015.Fertilizer Grain Grain removalN P2O5 K2O N P K N P K N P K----------- lb/a ----------- ---------------- % ---------------- -------------- lb/bu -------------- -------------- lb/a --------------0 0 0 1.07 0.267 0.372 0.52 0.131 0.182 39 10 130 40 0 1.05 0.315 0.393 0.51 0.154 0.192 42 13 160 40 40 1.04 0.312 0.391 0.51 0.153 0.191 42 13 1640 0 0 1.18 0.240 0.345 0.58 0.117 0.169 59 12 1740 40 0 1.14 0.317 0.378 0.56 0.156 0.185 70 20 2340 40 40 1.14 0.311 0.376 0.56 0.152 0.184 68 19 2380 0 0 1.36 0.227 0.339 0.67 0.111 0.166 77 13 1980 40 0 1.27 0.301 0.361 0.62 0.147 0.177 86 21 2580 40 40 1.24 0.312 0.369 0.61 0.153 0.181 84 21 25120 0 0 1.41 0.215 0.335 0.69 0.105 0.164 77 12 18120 40 0 1.36 0.288 0.356 0.67 0.141 0.174 96 20 25120 40 40 1.36 0.311 0.363 0.67 0.153 0.178 98 22 26160 0 0 1.45 0.236 0.345 0.71 0.115 0.169 88 14 21160 40 0 1.41 0.311 0.365 0.69 0.152 0.179 104 23 27160 40 40 1.39 0.292 0.358 0.68 0.143 0.176 100 21 26200 0 0 1.45 0.242 0.349 0.71 0.119 0.171 91 15 22200 40 0 1.42 0.294 0.365 0.70 0.144 0.179 101 21 26200 40 40 1.43 0.297 0.363 0.70 0.146 0.178 103 21 26continuedKansas State University Agricultural Experiment Station and Cooperative Extension Service62016 SWREC Agricultural ResearchTable 2. Nitrogen, phosphorus, and potassium fertilizers on grain N, P, and K content of irrigated grain sorghum, Tribune, KS, 2006-2015.Fertilizer Grain Grain removalN P2O5 K2O N P K N P K N P K----------- lb/a ----------- ---------------- % ---------------- -------------- lb/bu -------------- -------------- lb/a --------------ANOVA(P>F)Nitrogen 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001Linear 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001Quadratic 0.001 0.009 0.001 0.001 0.009 0.001 0.001 0.001 0.001P-K 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001Zero P vs. P 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001P vs. P-K 0.502 0.718 0.876 0.502 0.718 0.876 0.659 0.890 0.986N×P 0.705 0.014 0.221 0.705 0.014 0.221 0.118 0.002 0.019MEANSNitrogen,lb/a0 1.05e 0.298a 0.385a 0.52e 0.146a 0.189a 41e 12c 15d40 1.15d 0.289ab 0.367b 0.57d 0.142ab 0.180b 66d 17b 21c80 1.29c 0.280bc 0.356cd 0.63c 0.137bc 0.175cd 82c 18a 23b120 1.38b 0.272c 0.351d 0.68b 0.133c 0.172d 90b 18a 23b160 1.42ab 0.280bc 0.356cd 0.69ab 0.137bc 0.174cd 97a 19a 25a200 1.43a 0.278bc 0.359c 0.70a 0.136bc 0.176c 98a 19a 25aLSD(0.05) 0.04 0.012 0.007 0.02 0.006 0.003 4 1 1P2O5,lb/a0 1.32a 0.238b 0.348b 0.65b 0.117b 0.170b 71b 13b 19b40 1.27b 0.304a 0.370a 0.62a 0.149a 0.181a 83a 19a 24a80 1.27b 0.306a 0.370a 0.62a 0.150a 0.181a 83a 20a 24aLSD(0.05) 0.03 0.008 0.005 0.01 0.004 0.002 3 1 1

Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum

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Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum

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