Irrigation and cropping effects on soil chemical properties at São Francisco river basin

Abstract

Irrigation and cropping effects on soil properties were studied in the region of the Low-Medium São Francisco river basin. Six sites were selected, three of them involving Oxisols collected at the Senador Nilo Coelho Project, in the municipality of Casa Nova, BA, whereas the other three involved Ultisols collected at the Curaçá Irrigation Perimeter in the municipality of Juazeiro, BA. The selected sites involved non irrigated and irrigated land, different crops and irrigation methods. The soils were morphologically characterized and samples were taken from each horizon to determine pH, organic carbon, extractable phosphorus, exchangeable bases, cation exchange capacity, base saturation and aluminum saturation. Chemical properties were differently affected depending upon the management practices. The sites with tree crops and sprinkler or drip irrigation systems showed increases in the pH and exchangeable bases, and a decrease in aluminum saturation of the surface horizons. On the other hand, in the sites with annual crops and furrow irrigation, a decrease was observed in the exchangeable bases and base saturation, along with an increase in aluminum saturation. No tendency towards salinization was observed in the area, demonstrating that the limitations reported in the region are generally related to the high water table observed in the ultisols