Erosão e escoamento em parcelas experimentais após inserção de práticas conservacionistas

Abstract

Soil loss due to erosion of soil management in conjunction with wind and water has been indicated as a major cause of agricultural soil degradation. Considered as laminar or concentrated, it is responsible for the treatment of furrows and voices that even reduce agricultural areas, reduce biological production of soil and generate relevant economic and social problems. The objective of this work is to evaluate erosion and runoff in plots of 100 m² after the insertion of soil conservation practices. The data obtained in plots 1 and 2, with a slope of 3.4% and 3.6%, respectively, were used, the soil type has low permeability, hydrological group C, porosity equal to 0.398 and density of 1.65 g.cm-³, located in the Experimental Basin of São João do Cariri, PB. Seedlings of native Caatinga species were introduced and the fallow regime was maintained in plot 2. In the period from November 2014 to November 2016, only 20 rainfall events were observed with consequent runoff. The vegetation cover of plot 2 was maintained under irrigation until the month of November of the year 2015 and, during this period, it was possible to identify an increase of the runoff in plot 2 in relation to plot 1, with an increase of up to 40.5% due to the condition of antecedent soil moisture. In the year 2016, when there wasn’t irrigation, we observed a variation of the runoff in plot 1 from 0.71 to 3.51 times that observed in plot 2. The association of the regeneration of the undergrowth with predominance of species of the families Poaceae And Ciperáceas, due to the maintenance of the fallow regime in plot 2 and the insertion of native tree species native to the Caatinga biome, resulted in a significant reduction of sediment yield. This year the reduction of sediment yield was 32.06% in plot 2 in relation to plot 1, even though there was an increase of 0.7% of the runoff observed in plot 2 in relation to plot 1, which demonstrates the role of land cover on the reduction of soil loss in experimental areas. The Catingueira (Poincianella pyramidalis Tul.) showed the highest resistance to local climatic conditions without irrigation, and its use is recommended for restoration of vegetation in degraded areas.