Fluxos de água no consórcio milho-pastagem na microbacia hidrográfica do Rio Mundaú, Pernambuco

Abstract

In the context of world climate changes, the quantification of evapotranspiration (ET) of crops and grasslands is extremely important to anticipate how these changes will affect the hydrological cycle. Many researches were made to measurement of ET ongrasslands; however, there are few researches that measured ET and another soil water balance components in maize-pasture intercropping. The objective of this study was to assess the soil water balance components (soil water storage variations, drainage, capillary rise and evapotranspiration) of the maize-pasture intercropping under rainfed in the catchment Rio Mundau, Pernambuco State.The study was carried out in an experimental area located at the “Riacho do Papagaio” farm(8o 52’ 30’’ S, 36o 22’ 00’’ Wand 705 m), county of Sao Joao, from 01/01/2013 to 31/12/2013. TDR probes to measure the soil water content were installed at depths of 0.10, 0.20, 0.30 and 0.40 m. Rainfall was monitored with rain gauge installed on a tower at the center of the area. For the determination of drainage and capillary rise, infiltration tests were performed in field to obtain the saturated hydraulic conductivity. The soil water retention curve was determined in laboratory. The ETo was obtained by the Penman-Monteith method. It was observed that substantial soil water storage and ET values occurred in the high rainfall periods. The ET throughout the experimental period was the main water outlet of system with a total value of 406.8 mm and average of 1.1 mm d-1.The mean values of ET for periods with bare soil, maize-pasture intercropping and pasture alone were 0.8, 1.5 and 1.1 mm d-1, respectively. The maize-pasture intercropping must have suffered water stress, in almost all experimental period, due the values of the ratio ET/ETo being lower than the 1. The best period for the development of the forages (grasslands and maize) in the region is from april to august