Ciclagem de nutrientes por plantas de cobertura

Abstract

The sustainable practice of use of cover crops in middle of the traditional soybean-corn succession system is increasingly being recommended in the major producing regions of grain of those species, especially in the Amazon Biome. The high temperatures and high humidity in several times of the year occurring on those regions, causing factors that greatly accelerate the decomposition of straw from residues from previous crops, causing the soil less gain in volume of plant residues and reducing the rate of increase in the percentage of organic matter. The choice of a cover crop specie to be used by the succession must be linked to a number of factors such as physiology of the specie, morphology of specie, carbon / nitrogen ratio, rooting in depth, nutrients releasing time, ease of mechanization, leaves and stem distribution, diseases and pests breaking cycle as well the economic viability in no-tillage system. There are a lot of benefits provided by the use of cover crops, such as improving the physical properties of soil organic matter, protection to soil microorganisms, leached potassium recovery in deeper layers, moisture

xiii retention, reduction of the organic carbon oxidation as well the reduced presence of weeds in fallow periods in the off season and less amount of pesticide applications, stimulants and chemical fertilizers. But such selection should be careful to avoid possible adverse effects resulting from cover crops such as hosting pests and diseases, mulching excess with low nutrient releasing, allocation of dormant seeds, fertility depletion, and competition for water, light and nutrients when associated with rotation crops system.