Consumo energético no cultivo de feijão sob diferentes estratégias de manejo de irrigação em pivô central

Abstract

Sustainable use of water is an actual agenda, and according to estimates of the Intergovernmental Panel on Climate Change (2014) the lack of rain will occur more often, which will lengthen the soil drought, making harder the non-irrigated agricultural production. The management of irrigation is an essential tool used to irrigation systems, but there is still much to be studied so that it can reduce the costs of using the water, which is a scarce and expensive element to be pumped to the fields of production. This study evaluated three irrigation management strategies by climate, through the mathematical model of Penman-Monteith in two different sowing times for the common bean cultivar Carioca, the first starting in February and the second in May. The first, management strategy consisted of daily applications of a blade of 5mm; the second, consisted of daily applications of a variable blade, which corresponded to the amount of water transpired for 24 hours; and the third, consisted in a safety margin obtained from the difference between the Readily Available Water (RAW) and the negative accumulated (NA), when RAW - NA > 13 it did not occur irrigation; 13 > RAW - NA > 10.5 the water blade corresponded to 80% of the water need of the day; and when 10.5 > RAW - NA the water blade corresponded to 105% of the water need. Contrasting the three methodologies, the use of fixed blades with fixed irrigation frequency has considerably wasted water and electricity, the use of fixed irrigation frequency tends to have lower efficiency in the use of water resulting from rainfall than variable irrigation frequency.