Tillage systems and cover crops on soil properties in Northeastern Brazil

Abstract

ABSTRACT Long-term experiments combining tillage systems and cover crops are essential to understand variation in soil physical and chemical properties under different environmental conditions, but data from Brazilian tropical Ultisols under conservation management remain scarce. This study evaluated the effects of conventional tillage (CT), minimum tillage (MT), and no-tillage (NT), associated with different cover crops, on the physical and chemical properties of a Typic Hapludult. The experiment, conducted since 2001 at the Rural Campus Experimental Station of Universidade Federal de Sergipe, was cropped with maize (Zea mays) under the three tillage systems, each combined with sunn hemp (Crotalaria juncea), pearl millet, pigeon pea, and cowpea. Soil samples were collected from the 0.00-0.10 and 0.10-0.20 m layers. Soil bulk density in the 0.00-0.10 m layer was significantly higher under NT than under the other tillage systems, indicating surface consolidation under the absence of soil disturbance. Conservation tillage systems, particularly MT and NT, showed higher soil organic matter contents in the surface layer, and in both layers NT resulted in significantly higher soil organic matter content than CT and significantly higher soil carbon stocks than those observed under CT and MT. Among the cover crops evaluated, sunn hemp exhibited the greatest potential for soil organic matter increase. The results suggest that conservation tillage systems, especially when integrated with leguminous cover crops, may increase soil carbon stocks and contribute to improved soil quality in tropical Ultisols under continuous maize cropping.