Balanço hidrico no solo cultivado com a cultura da cunhã (Clitoria ternatea L.) sob recarga natural

Abstract

The butterfly pea (Clitoria ternatea L.) is a perennial legume, grow n as a protein rich forage and well adapted to the warm and semi arid climate. Soil water balance is important for determining water availability and enabling crop production, streamlining the use of resources. The objective of this study was to quantify a nd analyze the water balance components for the butterfly pea crop in a physical field model, in sloping area and under natural recharge conditions. In the experimental plot two tensiometer batteries were installed at different depths to calculate the tota l and matric potentials, moisture content and percolation. Surface runoff was also monitored. Agrometeorological data were used for precipitation and calculation of reference evapotranspiration. Precipitation during the experiment was 365.2 mm. In the anal yzed period, the vertical movement of water in the ground always occurred in the downward direction. The accumulated water outlets were: deep drainage (64.33 mm), runoff (76.1 mm) and evapotranspiration (224.77 mm). Although difficult to measure, deep and superficial drainage accounted for approximately 40% of soil water outlets, showing that it should not be disregarded. The adopted conditions allowed a smaller runoff than the reference (30%), indicating less erosion. The butterfly pea did not suffer from stress due to water deficit, with evapotranspiration being the main output component. The other components of outlets were percentage significant, indicating that if ignored, there is a risk of overestimation of available water in the soil.