Physical properties of soil cultivated with Jatropha curcas and associated green vegetation covers

Abstract

The cultivation of physic nut (Jatropha curcas L.) is a sustainable option for biodiesel production due to its adaptation to different agro-ecological conditions and its high content of non-edible oil grains. The possibility of its cultivation in degraded low fertility soils makes the physic nut attractive to the Paraíba do Sul Valley region. This study evaluated physical attributes and water processes of an Oxisol which had been previously used for livestock and later converted to experimental farming. The soil was intercropped with perennial herbaceous legumes (Arachis pintoi and Calopogonio muconoides) in place of the original cover of Brachiaria brizantha, largely cultivated in the region. We determined the soil texture, the levels of saturation and water retention, soil resistance to root penetration and the basic infiltration rate of water into the soil (VIB). The soil resistance to root penetration in B. brizantha ranged from high to moderate at 30 cm depth, while the addition of perennial herbaceous legumes as cover crops intercropped with Jatropha reduced this resistance and increased the average soil VIB from 4 mm h-1 (B. brizantha) to 33 mm h-1. We conclude that the association of herbaceous legumes with Jatropha contributed to the improvement of the soil’s physical properties.