Balanço hídrico normal e da sucessão soja milho da Bacia do Rio Caiabi

Abstract

This study aimed to estimate the climatological water balance of watershed water catchment area of river Caiabi, for the period 2011 to 2014, and for water balance using soy and corn systems, early and normal cycle, with the planting in the third 10-day period of october. Available water capacity (AWC) adopted for the water balance of watershed and for estimating the stock of cultures was determined in the laboratory from soil samples collected in layers of 10 and 30 cm troughout the watershed. The methodology adopted for determination of potential evapotranspiration was Camargo(1971), being extraterrestrial global solar radiation determined by latitude and solar declivity. The estimated results for the AWC of watershed for the depth of 0-40 cm is 85,78 mm, being the 0-20 cm layer with the greatest potential, 56.5 mm. The deficit and surplus of water stands respectively in -450,6mm e 901,3mm, with influences of atypical events bringing the surplus value. Systems that use only cultivars of normal cycle has the potential of second crop reduced by long periods who the crops remain in the field. The smaller hydric deficit of the culture systems are those who adopt only early cultivars, as well as the indexes obtained by the normal cultivars and early cycle satisfactory.