Corn Growth as Affected By Ammonium vs. Nitrate Absorbed From Soil1

Abstract

AbstractThe 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 symptomatic of 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.