Soil mobilization, erosion and corn and bean yields in a Regosol on the Pernambuco State dry area

This study was conducted in Caruaru County, PE, Brazil, from 1970 to 1990, in an eutrophic Regosol 12% slope, to evaluate different soil tillage methods on soil and water losses and corn (Zea mays L.) and bean (Phaseolus vulgaris L.) productivity under natural rainfall conditions. Data were obtained from four 1,000 m(2) experimental plots equiped to collect eroded material from the following treatments: hoe (manual), plow and harrow, double plow and harrow, and only harrow. The mean annual soil and water losses was higher with plowing twice and harrowing and with plowing and harrowing treatments, but, in general, the losses were low in all treatments. This fact was attributed to the large amounts of gravel and coarse sand in the soil profile by reducing direct impact of rain drops and increasing permeability. The more intensive soil tillage methods, by placing richer layer in nutrients deeper, where more water is available, increase nutrient absorption resulting in higher productivity specially for corn. There was significant correlation between corn productivity and average P content from 9 to 14 cm, 10 to 19 cm and 14 to 22 cm depths.