Optimal Plant Population and Nitrogen Fertility for Dryland Corn in Western Nebraska
2003
Blumenthal, Jürg M. | Lyon, Drew J. | Stroup, Walter W.
Dryland corn (Zea mays L.) production increased more than 10-fold from 1995 through 2000 in semiarid western Nebraska. Corn population and N fertilizer management recommendations are needed for this area. The objectives of this study were to determine the influence of plant population and N fertility on corn yields in semiarid western Nebraska. In 1999 and 2000, experiments were conducted each year at four sites. Factorial experimental treatments were five plant populations (17300, 27200, 37100, 46900, and 56800 plants ha⁻¹) and five N fertilizer rates (0, 34, 67, 101, and 134 kg N ha⁻¹) arranged in a randomized complete block with five blocks. Corn yields ranged from less than 100 kg ha⁻¹ to more than 5550 kg ha⁻¹ Overall, grain yield increased 353 kg ha⁻¹ with increasing population from 17300 to 27200 plants ha⁻¹ Population increases above 27200 plants ha⁻¹ resulted in inconsistent yield results. Nitrogen fertilization and plant population effects did not interact. Yields were maximized by 202 kg N ha⁻¹ in the form of soil NO₃–N and fertilizer N available before crop emergence. Growers are advised to use a plant population of 27200 plants ha⁻¹ Economic optimal fertilizer rate can be estimated using the equation: N fₑᵣₜ. = (10.6 × P cₒᵣₙ − P fₑᵣₜ.)/(0.0526 × P cₒᵣₙ) − N ₛₒᵢₗ, where P cₒᵣₙ and P fₑᵣₜ. are corn and fertilizer price ($ kg⁻¹), respectively, N ₛₒᵢₗ is soil test NO₃–N (kg ha⁻¹) as determined by preplant soil test in a 0- to 120-cm soil sample, and N fₑᵣₜ. is economic optimal fertilizer rate (kg ha⁻¹).
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