Evapotranspiration of Sudan grass grown as secondary crop on irrigation

Abstract

The experiment was conducted with Sudan grass, grown as secondary crop for silage оn irrigation during the period of 2014–2015 in the experimental field of the Agricultural Institute, Stara Zagora on soil type Meadow Cinnamon. The following variants were tested: Variant 1 - without irrigation; Variant 2 - optimal irrigation, 70-75% of FC (100% irrigation rate); Variant 3 - irrigation as variant 2 but without first watering; Variant 4 - irrigation as variant 2 but without second watering; Variant 5 - irrigation as Variant 2 but without third watering. Evapotranspiration of the Sudan grass during the vegetation period was determined based on water balance equation. The average daily evapotranspiration of Sudan grass in the experimental years varies from 2,1 mm to 4,5 mm and it is dependent on the amount of precipitation and meteorological situation over the years. Evapotranspiration of Sudan grass as maintaining 70-75% of FC, average for two-year study period amounted to 247,05 mm, as its daily average value reaches its maximum in phase tasse ling - 4,5 mm per day.