R. Bazitov, A. Stoyanova
Abstract. During the period of 2009–2012 in the experimental field of the Agricultural Institute, Stara Zagora on soil type meadow cinnamon soil was conducted experiment with silage corn first crop. Corn was grown after predecessor wheat – pea mixture. Five options of irrigation regime of maize were examined. It has been found that during the years of prolonged drought when sowing of corn is in non-irrigated evapotranspiration embodiments in the range of 301.5 to 308.4 mm, and in average wet years with uniform distribution of precipitation greater than 350 mm. Under conditions of irrigation evapotranspiration of culture was increased to an optimal embodiment irrigated reaches values 471.4 mm, and an irregular irrigation regime – 397.2 mm and 372.3 mm, respectively, in 60% M, and 40% M. Average for the three years of study, evapotranspiration reaches maximum average values during the second ten days of August – 6.13 mm at the optimal option and 3.76 mm for versions without irrigation in phase tasseling-dark silks, and then at the end of the vegetation gradually decreases and reaches values of 3.70 mm to 2.20 mm.