Irrigation efficiency and water productivity in the fields of Semnan province (Shahrood)

The main strategy for efficient water usage in agriculture is decreasing water losses and increasing irrigation efficiency. Therfore evaluation of different irrigation management and their performance is essential for improvingirrigation methods and increasingirrigation efficiency. In this research, on-farm surface irrigation efficiencies and water use efficiencies were measured in sugarbeet and potato farms in Semnan province(Shahrood) during the years 2010 and 2011. For this research, 6 farms were selected and were evaluated. Water discharge, runoff rates, soil moisture before and after irrigation, rooting depth and yield were measured and different irrigation efficiencies and water use efficiencies were determined.The irrigation efficiencies were determined three times in each farm (early, middle and late season). The results showed that maximum losses occured in the first irrigation. The average irrigation application efficiency were about 34.1and 31.3% respectively. The study showed that substantial amount of water losses were in the form of deep percolation. Unsuitable beginning time of irrigation and unsuitable irrigation water amount with regard to plant water requirement, inattention to soil characteristics and slope of plots in selection of depth and length of furrow and low entrance discharge of furrows caused water losses in farms. The average water use efficiencies for these crops were about 4.2 and 2.03kg/m3 respectively. Suitable farmer management with regard to water requirement of farms and their good scientific and experimental information were the main factors of water use efficiencies increment in the farms.