Liming and molybdenum effects on nitrogen uptake and grain yield of corn

Abstract

Subsoil acidity and calcium deficiency are the main chemical impedance to root growth in highly weathered soils. In order to study the effects of liming, Mo, and their interactions on nitrogen uptake and grain yield of corn, an experiment was carried out on a Pachic Haplumbrept soil, in the State of Sao Paulo, Brazil. The trial was in a split-plot design, with five rates of limestone (0, 3, 6, 9, and 12 Mg ha−1) and three rates of Mo (0, 50, and 100 g ha−1) applied as seed treatment. Two consecutive maize crops grown during 1986 to 1988 showed large response to liming with average grain yield ranging from 250 to 7,850 kg ha−1. Liming of the surface soil promoted amelioration of the soil down to 100 cm, increased root growth and nutrient absorption, mainly nitrogen, which increased about ten fold. Nitrate reductase activity (NRA) also varied in the same pattern as N absorption. Addition of Mo did not raise grain yield, but increased its content in the leaves. It was concluded that amelioration of subsoil layers by liming of the surface soil improved root elongation in the subsoil, which contributed to prevent nitrogen losses by leaching.