Corn Growth as Affected By Ammonium vs. Nitrate Absorbed From Soil
1976
Dibb, D. W. | Welch, L. F.
The effect of NH₄ on corn (Zea mays L.) growth in a soil medium is of interest because of the possibility of significantly decreasing leaching and denitrification losses of applied N by preserving N in the NH₄ form. The objective of this investigation was to determine growth and nutrient content of corn plants when the principal form of N was either NH₄ or NO₃. Corn, grown in the greenhouse in a soil medium, was allowed to absorb N as either NH₄ or NO₃. A chemical nitrification inhibitor and different sources of added N were used to manipulate the form of N available for absorption. The maximum amount of N absorbed as NO₃ was estimated as the difference between the NO₃ content of fallow and cropped pots at harvest. Plants grown with NH₄ and a nitrification inhibitor were estimated to have absorbed at least 95% of their N as NH₄. Other plants absorbed N almost solely as NO₃. The effect of NH₄ versus NO₃ absorption on stover yield, percent N, Ca, Mg, K, and P in the plant was determined. Yield of corn plants was not negatively affected by form of N absorbed when the meq ratio of applied N:K was 2:1. Visual tissue damage and decreased yield were symptomatico f NH₄ nutrition where the meq applied N:K ratio was 3.3, 4.0, 4.4, 6.6, and 8.0. Nutrient content of the plants reflected strong cation:cation and cation:anion interactions among N form absorbed and Ca, Mg, K, and P. Soil pH appeared to be affected less by form of N absorbed by the corn plants than by nitrification of applied NH₄.
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