Balanço hídrico no solo cultivado com feijão caupi

Abstract

The water balance components (evapotranspiration, variation of the water storage in the soil, deep drainage, capillary rise, rainfall), were determined for an Oxisoil cultivated with cowpea (Vigna unguiculata (L.) Walp.). An automated rainfall gauge and three plots were installed in an area of 4 ha in the CCA/UFPB, Areia-PB (latitude 6o58’12" S, longitude 35o42’15" W, altitude: 620 m). Each plot consisted of an access tube for neutron probe measurements and a set of eight tensiometers. Infiltra- tion tests were performed for the determination of the saturated soil hydraulic conductivity. It was verified that the deep drainage was underestimated, due to the small value (-17.23 mm) found for that soil type. The variation of water storage in the soil followed the variations in rainfall. The eva- potranspiration was higher in the periods of increased water availability, with the average value of 4.12 mm d-1, and the greater water consumption occurred in the reproductive phase.