Comportamento do milho e feijão-caupi em rotação e diferentes coberturas vegetais no semiárido nordestino.

Abstract

Crops and others vegetal residues are used as death cover in minimum tillage in several regions of Brazil. In the Northeast this practice is not yet generalized and there is a poor knowledge about the plant residues degradation under semi-arid conditions and its effects on crop productivity and the physical and chemical soil characteristics. This work was carried out at Dry Farm Experimental Station, Quixada, Ceara, in order to evaluate the corn and cowpea yield growing under minimum tillage with two crop rotation systems, SPD1 (cowpea following corn) and SPD2 (corn following cowpea) and five types of death cover originated from natural vegetation, millet (Pennisetum americanum sin. tiphoydes); brachiaria grass (Brachiaria brizantha); forage sorghum, (Sorghum bicolor L. Moench) and conventional tillage. It was also evaluated the effects of these rotation systems and deaths covers over soil density, particle density, micro and macro porosity, percentage of soil humidity at 20cm depth of a Red Yellow Argissol during 2008 and 2009. It was not found significant differences between the biomass yields of brachiaria grass, millet and sorghum in SPD1 and SPD2. The deaths cover degradation during the two years of evaluation was higher where the cowpea was followed by corn. The corn yield was not significantly different between the death covers and conventional tillage. The better cowpea yield under conventional tillage could be caused by a better weed control. The death cover tested increased the soil density and decreases the macro and total soil porosity.