Corn Responses to Ammonium- and Nitrate-Nitrogen Fertilization
1992
Barber, K. L. | Maddux, L. D. | Pierzynski, G. M. | Kissel, D. E. | Bock, B. R.
Studies have indicated that, by maintaining relatively high solution culture or soil NH⁺₄/NO⁻₃ ratios during the reproductive growth stage, certain corn (Zea mays L.) genotypes have a higher yield potential. Unfortunately, few data on soil NH⁺₄ and NO⁻₃ levels have been reported. A 3-yr field experiment was conducted in northeastern Kansas in 1987, 1988, and 1989 to evaluate the effects of time and form of applied N on fertilizer band NH⁺₄/NO⁻₃ ratios and on the N nutrition, dry-matter accumulation, and grain yield of two corn hybrids. Urea, urea-NH₄NO₃, urea plus Ca(NO₃)₂, NH₄NO₃, and Ca(NO₃)₂ solutions having NH⁺₄/NO⁻₃ ratios of 1:0, 3:1, 1:1, 1:1, and 0:1, respectively, were used at equivalent N rates. The nitrification inhibitors, nitrapyrin [2-chloro-6-(trichloromethyl) pyridine] and dicyandiamide, as well as two-way and three-way timing of application schemes were used to maintain N as NH⁺₄. Split applications of ammoniacal N with a nitrification inhibitor were effective in maintaining elevated soil NH⁺₄ concentrations from planting through early grain fill. In 1988 only, grain yield was increased slightly (3–9% higher) when corn was fertilized with ammoniacal N compared with NO⁻₃ only. Overall, manipulation of soil NH⁺₄/NO⁻₃ratios had few effects on corn development or yield. Contribution no. 91-381-J from the Kansas Agric. Exp. Stn. This research was supported by the Fluid Fertilizer Foundation and the Tennessee Valley Authority.
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