RESIDUES ACCUMULATION ON THE SOIL SURFACE, CORN NUTRITION AND YIELD AS AFFECTED BY TILLAGE AND CROP SYSTEMS

Abstract

The objective of this study was to evaluate the effect of three methods of soil tillage (conventional, reduced and no-tillage), three crop systems (oats/ com, oats + clover/ com, and oats + clover/ com + cowpea) and two rates of nitrogen (0 and 120 kg/ha) on the accumulation of crop residues on the soil surface, com nutrition and yield. The accumulated crop residues on the soil surface, evaluated at the end of the year, varied from 3.09 to 5.60 t/ha of dry matter, and it was not affected by soil tillage, crop systems and N rates. The nitrogen was the most limiting nutrient to the com yield, and its availability was lower in no-till lago, as compared with conventional tillage. However the com yield was not affected by tillage methods and it varied from 2.39 to 5.72 t/ha. Without N application, use of legumes as green manure-cover crops increased com yield up to 81% and it was correlated with total amounts of N in the biomass on the soil surface (residues plus winter crops). The conservation management systems, that associate no-tillage or reduced tillage, and legumes for cover and N addition, resulted in relatively high com yields. In addition, they have benefits due to soil cover crop residues during a larger period of the year, compared with conventional soil management systems.