Caracterização hidrológica dos solos da bacia experimental do Ribeirão Concórdia, Lontras/SC

Lizandra Poeta Teixeira

The knowledge of the physical and hydraulic soil properties is highly important to both use and appropriate management of the soil, as well as the understanding of the dynamic process of water and solutes movement. This work has the finality to generate knowledge about the hydrological characteristics of the soil of the experimental Basin of Ribeirão Concórdia, located in the municipality of Lontras in Santa Catarina. It is insert among the microbasins monitored by the Project for Environmental Recovery and Support for Small Producer Rural (PRAPEM/MICROBACIAS), developed by the Secretary of State for Agriculture and Rural Development of Santa Catarina. The Ribeirão Concórdia basin holds a drainage area of 29,74 km2. The predominant soils are Red-Yellow Podzolic. The study involved the soil sample collection at three depths (0 to 20, 40 to 60 and 80 to 100 cm) and the fulfillment of infiltration testing in 20 sampling points, which presents different soil uses and management. From the samples were analyzed the physical characteristics: granulometry, real specific mass, apparent specific mass, porosity and humidity. The infiltration tests were unidimensional, carried through by a concentric-ring infiltrometer with 25 and 50 cm diameter, and three-dimensional, carried through with a simple ring, whose assay was effected with small penetration in the soil. With the granulometric curves and the infiltration capacities of the threedimensional assay were estimated the parameters of the retention and hydraulic conductivity curve by the Beerkan method. The granulometric curves indicate that the soils are, in general, silt loam, having some samples classified as silt clay loam. The specific masses measures for the three layers of the soil profile varied between 0,928 g cm-3, at 0-20 cm layer, of amostral point 1, in which the use of the land is perennial pasture, and 1,84 g cm-3, at 80-100 cm layer of amostral point 3, where the use of the land is pine forest planted about 3 years. The mea rate values of specific mass increased with increasing of depth. In the layer 0-20 cm, it was 1,27 g cm-3, increasing to 1,31 g cm-3 in the intermediate layer of 40-60 cm and in the deeper layer of 80-100, the specific mass media was of 1,32 g cm-3. The porosity varied from 64,11% in the 0-20 cm profile in the sampling point 1 (use of the land for perennial pasture) and 28,41% in 80-100 cm profile in amostral point 3 (pine plantation). Reduced values of porosity were found in the native forest, varying between 35 and 39%. The initial infiltration capacity adjusted to the Horton equation had varied between 0,8 (pasture) and 5,0 cm min-1 (pine forest and cassava plantation). In the pasture areas the adjusted initial infiltration was of 0,8 and 0,9 cm min-1. Regarding the minimum value, they varied between 0,01 (perennial pasture) and 0,3 cm min-1 (maize in minimum tillage). In forest areas, the minimal infiltration ranged between 0,05 and 0,15 cm min-1 and in pasture areas, was equal to 0,01 cm min-1. The biggest value of saturated hydraulic conductivity was obtained in the native forest (0265 mm s-1) and the lowest value was in the maize area with conventional tillage (0,013 mm s-1). It is observed that there is a gradient of total potential in the soil matrix, ranging from native forest, pine forest, maize and pasture

Caracterização hidrológica dos solos da bacia experimental do Ribeirão Concórdia, Lontras/SC

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