Crop Recovery and Nitrification of Fall and Spring Applied Anhydrous Ammonia
1975
Chalk, P. M. | Keeney, D. R. | Walsh, L. M.
To evaluate the relative agronomic efficiency of and potential NO₃, pollution by fall and spring applied anhydrous NH₃, N uptake and yield response by corn, and detailed sampling of the NH₃, bands were conducted. Nitrogen significantly increased grain yield and N uptake by corn (Zea mays L.) on a Plano sil (0.216% N) and a Pella loam (0.447% N) in south central Wisconsin. There were no differences between fall and spring application of N. Crop recovery of applied N depended on soil type and rate of application, and at most amounted to 40% of the N applied. Depending on rate of application, from 68 to 86% of the fall-applied NH₃, was nitrified before mid-May. Nitrite accumulated within both fall and spring applied bands, the highest concentrations being detected in early spring within fall applied bands. Persistence of NO₂ was more prolonged on a neutral than on a slightly acid soil. Accumulation of NO₂ must be considered undesirable because of possible phytotoxicity and losses through biological or chemical denitrification, and fall application appears to offer a great potential for these processes to occur.
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