Contribuições de componentes vegetais na qualidade do solo em sistema agrossilvipastoril no semiárido

Abstract

The study of chemical, physical, as well as the micromorphology may provide support to enable more detailed knowledge of fertility and porosity of the soil, allowing the understanding of the chemical and structural differences ground provided by the plants in alternative systems in semiarid. Based on this, the hypothesis has suggested that plantcomponents have differentials effects in fertility and soil structure under agroforestry system semiarid region of Ceará. In this study the objective was to evaluate the differences in soil fertility, the distribution of pore space, as well as the shape and size of pores of a Aridsol the area of influence of plant components - shrub (Leacaena leucocephala), tree (Poincianera pyramidalis) and agricultural (Zea mays) and natural regeneration area. The work was conducted in agroforestry system in Centro de Convivência com o Semiárido, Embrapa Caprinos e Ovinos, Sobral, CE. Sampling for chemical analyzes were performed at depths of 0-5, 5-18, 18-25 and 25-41 cm, the area of influence of the above species. Samples for physical and micromorphological analyzes were performed by collecting samples preserved structure, corresponding profiles in the areas of coverage of species, including natural regeneration area, covering the depths cited. The evaluated chemical parameters were: pH, total organic carbon (COT), total nitrogen (N), total phosphorous (P), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+), sum of bases (SB), cationic exchange capacity (CTC), base saturation (V%), aluminum saturation (m%) and percentage of sodium saturation (PST). To evaluate the structure have been made: the bulk density (DS), penetration resistance (RP), permeability intrinsic soil air (Kar), continuity index of pores (K1 and N), water retention curve in the soil, S index and total porosity and pore distribution by size and shape. It was image analysis study employed in blocks impregnated with polyester resin and ultraviolet contrast. Data from the chemical attributes were analyzed in a completely randomized design with split plot with four replications in space, the physical data considering a completely randomized design in bands and four replications and porosity by the image method, completely randomized design. By the significant F test was used to test Scott Knott 5% probability. The soil in the area of influence of shrubs and trees components exhibited improvements in soil fertility and structure, with lower density, lower resistance to penetration, increased permeability of the intrinsic soil to air and total area of pores, with a predominance of complex pores and large, which act as alternative routes for root growth and favor water infiltration into the soil, contributing to soil and water conservation in agroforestry system in semiarid region. It was concluded that: the superiority in some physical and chemical attributes in the area of influence of shrubs and trees components reinforce the importance of these components in soil improvement and sustainability in semiarid agroecosystems; with 2-D analysis was scanned images can detect differences in the soil caused by the plant components via pores greater detail as to the amount, size and shape.