Improving Cotton Yield, Water Use and Net Income in Different Drip Irrigation Systems Using Real-Time Crop Evapotranspiration

The purpose of this study was to improve irrigation water use and cotton yield using real-time crop evepotranspiration based on the FAO-56 Penman-Monteith and canopy cover using surface drip and subsurface drip irrigation. The experiments were conducted Southeast Anatolia Region of Turkey, during 2016 and 2017. The experimental design was split-plots in randomized blocks using three replications. The main plots were surface drip irrigation (SDI), subsurface drip irrigation (SSDI-30 cm) and SSDI-40 cm. Sub-plots were three different irrigation levels based on real crop evapotranspiration (ETc), 0.75xETc, 1.00xETc and 1.25x ETc. There were significant differences (657 kg ha(-1)) between the seed cotton yield of SDI (3667 kg ha(-1)) and SSDI with a 40-cm lateral depth (4323 kg ha(-1)). Irrigation water and crop consumptive water use were 552 and 589 mm for the SSDI-40 cm recommended treatment, respectively. According to the projection using the results for cotton cultivation area in the study region, SDI and SSDI could save water about 37 and 42% compared to furrow irrigation, respectively. Net income based on unit area in SDI and SSDI was higher 20 and 69% than it in furrow irrigation, respectively. Irrigation scheduling based on real crop evapotranspiration (1.0xETc) was more appropriate for water saving and increasing water productivity (0.84 kg m(-3)). The use of drip irrigation systems (especially SSDI) is significantly important to improve cotton yield, water use and economic contribution considering possible water shortage, decreasing water resources, farmers conditions, irrigation schemes, regional and national incomes.