Manejo da cobertura do solo e de práticas conservacionistas nas perdas de solo e água em Sumé, PB

Abstract

Resumo Resumo ResumoResumo Resumo: Foram estudados os efeitos do manejo e da cobertura do solo sobre as perdas de solo e água provocadas por chuvas erosivas, num solo Bruno Não-Cálcico. Os dados correspondentes aos anos de 1983 a 1990 foram obtidos na Bacia Experimental de Sumé, PB, inserida dentro da Bacia Representativa de Sumé e operada pela Universidade Federal da Paraíba (UFPB), Campus II, Campina Grande. O experimento constituiu-se de uma parcela desmatada e mantida em alqueive contínuo, de duas desmatadas, uma com caatinga nativa, de duas parcelas com cobertura morta, uma com palma cultivada morro abaixo e de uma parcela com palma cultivada em nível. A parcela desmatada em alqueive contínuo contribuiu com perdas anuais de solo e água de 23,1 t ha -1 e 201 mm, respectivamente. Nas parcelas desmatadas as perdas de solo e água foram de 35,7 e 58,5 t ha -1 e 224,2 e 241,0 mm, respectivamente, enquanto a parcela com caatinga nativa e quando comparada com a parcela desmatada, teve uma redução na perda de solo em cerca de 99% e na perda de água em torno de 89%; já nas parcelas com cobertura morta houve redução de aproximadamente 99% das perdas de solo e 74% das perdas de água em relação às parcelas desmatadas. A palma cultivada em nível reduziu as perdas de solo em 53,4%, quando comparada àquela cultivada morro abaixo. The effect of the soil cover management and conservation practice on soil and water losses caused by the erosivity of rainfall in Haplargid soil have been analyzed in this paper. The field data corresponding to the years 1983-1990 were collected at the Experimental Basin of Sumé, PB operated by the Federal University of Paraíba (UFPB). The experimental data resulting from one erosion plot cleared bare of vegetation and continuously ploughed in, two cleared bare runoff plots, one runoff plot with native semiarid vegetation, two mulched runoff plots, one plot with cactus planted down the slope and one plot with cactus planted along contour lines were used in the analysis. The bare ploughed plot contributed with annual soil and water losses of 23.1 t ha

Characteristics of rainfall and erosion under natural conditions of land use in semiarid regions

“…This is due to the protective effect provided by trees, which contributed to a greater dissipation of the kinetic energy of the raindrops, reducing the detach process of the soil particles and consequently reducing soil loss by erosion. A reduction of up to 99% in soil loss in native 'caatinga' plots can be found when compared with bare plots (Albuquerque et al, 2002).…”

“…This difference is associated with the removal of the vegetation from the area keeping a bare soil. Albuquerque et al (2002), studying the management of ground cover and conservation practices for soil losses in Sumé, Paraíba, obtained higher values of soil loss for the bare soil plot, being 231 times greater in relation to the plot with native caatinga.…”

“…For the thinned-out plots (Table 2), soil losses ranged from 163.79 to 718.38 kg ha -1 for intermediate and earlypattern precipitation respectively. This can be explained by the combination of high kinetic energy which occurs in the early pattern rainfall, and the condition of the bare soil creating greater detachment of particles by the direct impact of raindrops onto the soil (Albuquerque et al, 2002;Carvalho et al, 2009). Water loss followed the same trend as that of soil, with losses for the early pattern being greater than for the IN and LA patterns and for the events with two rainfall patterns, by around 131, 49 and 483% respectively.…”

“…In the thinned-out area, as well as the remaining arboreal vegetation, there were twigs and tree branches left on the ground after treatment, minimizing the impact of raindrops on the ground and forming barriers against the runoff. There are several studies that show the efficiency of vegetation and debris from cultivation in erosion control (Albuquerque et al, 2002, Santos et al, 2007.…”

“…The low availability of data obtained "in situ" is due to the high costs, the difficulties in affecting these measurements and also the long time required to obtain reliable results. Several researchers in various parts of Brazil point out to the scarcity of data and research in the field to evaluate soil losses (Albuquerque et al, 2002;Santos et al, 2007;2011). One way to reduce this limitation is to install experimental watersheds.…”