Perda de solo por erosão em decorrência da ação de adubação fosfatada corretiva sobre a estabilidade de agregados

Abstract

Phosphorus application in Brazilian soils is a common practice and such operation may affect some soil properties. Thus, with the objective of measuring the effect of the phosphate fertilization on aggregate stability and soil loss by erosion of a typic Acriferric Red Latosol from Lavras (MG), soil plots were fertilized with the equivalent to 450 kg ha-1 of P2O5, broadcasted, and 180 kg ha-1 of P2O5 applied over lines, in two plots of 72 m2. Aggregate stability was measured by sonication at different sizes of aggregates: 7.93 to 4.76; 4.76 to 2.00; 2.00 to 1.00; 1.00 to 0.50; 0.50 to 0.25 and <0.25 mm. Wet sieving was also performed to estimate aggregate stability at the fraction of 7.93 to 4.76 mm. The amount of erosion was measured using a grid of pins on soil surface. Phosphate fertilization significantly reduced aggregate stability by wet sieving and ultrasonic for larger aggregates than 1 mm, and increased the erosion in 2.85 times. Aggregates larger than 2 mm showed stability 2.83 times lower with phosphate, which could influence soil loss. The phosphate fertilization reduced the zero point of salt effect, and increased the negative charges density, which helps to explain these results.