Avaliação da influência de práticas conservacionistas sobre a geração do escoamento superficial e produção de sedimentos em parcelas experimentais no Semiárido Paraibano.

Abstract

In the Brazilian semiarid zone, the pressure of productive activities on natural resources has favored the increase of areas undergoing desertification and the increase in silting of rivers and lakes, which compromises water quality, aquatic biodiversity and storage capacity in surface reservoirs. The objective of this study was to evaluate the influence of conservation practices on the generation of runoff and sediment yield in experimental plots in the semiarid region of Paraíba. Two experimental plots of 100 m², located in the Experimental Basin of São João do Cariri (BESJC), middle part of the Taperoá River basin, 206 km from the city of João Pessoa, PB, comprise the study area of this study. Experimental plots 1 (P1) and 2 (P2) have an area of 100 m² (4.5 m x 22.2 m), average slope of 3.6% and 3.4%, respectively. Plot 1 was always kept without vegetation cover and Plot 2 was kept fallow from 1999 to 2002. In 2018, a combined conservation practice was introduced, consisting of planting 22 seedlings of native Caatinga species, removal, transport and use of a neighboring soil, with a larger seed bank over the entire area of P2, covered by crushed sugarcane bagasse in forage, to evaluate the efficiency of this practice on the generation of runoff and sediment yield. The quantification of runoff and sediment yield follows a standard script established in the 1990s, in the Sumé Experimental Basin. A total of 131 precipitation events with consequent surface runoff and sediment yield were selected from 2009 to 2011, 2015 to 2016, and 2018 to 2023, which occurred in plots 1 (P1) and 2 (P2), taking into account the classification of years as dry, normal, and rainy, according to the total annual precipitation. The combined conservation practices implemented in the area of plot 2 (P2) in 2018 and maintained to date were efficient and effective, with a reduction of 45.4% to 100% in the runoff depth and 67.9% to 100% in sediment yield compared to plot 1 (P1), favoring an increase in humidity and the reactivation of the biogeochemical cycle within the soil.