Water demand and irrigation requirement of grassalands in the region of Tubarão, Santa Catarina

The work aimed to evaluate the need for pasture irrigation in the soil and climate conditions of Tubarão, SC. Historical series of daily precipitation of Tubarão (02849027 code, latitude 28° 28 ‘ 20 “S, longitude 48° 59 ‘ 28” W) were used during the 1980 to 2011 period. Average reference evapotranspiration values for five days were considered. With the use of the daily water balance technique, water demands and the needs of irrigation in monthly periods were determined, considering soils with water storage capacity (CAD) of 25, 50, 75, 100 and 125 mm. It was observed that there is need for pasture irrigation between the months of October to January, mainly in soils with low CAD. Soils with 25 CAD require on average 31.8 irrigations per year. Irrigation can be an important tool to keep pasture production and should be planned in such a way as to supplement rainfall.