Effect of Plastic Mulch Placement in Furrow Irrigation on Water Productivity of Fodder Corn

Surface irrigation systems have been widely used in in arid and semi-arid regions of the world, but inappropriate design and management has led to high water losses and reduced water productivity. The objective of this research was to investigate the effect of plastic mulch placements in furrow irrigation on soil water distribution and water productivity under fodder corn production. Field experiments were carried out in Karaj in 2018. Four different treatments were considered in terms of plastic mulch placements including mulch on the ridge (R), mulch on the furrow bed (F), mulch on the ridges and the furrow bed (FR), and a treatment without mulch or control treatment (C). In order to measure water content, soil samples were taken one day before and three days after each specific irrigation event with 5 days intervals from four points (at 0-25 cm and 25-50 cm under the ridges and furrows) for all treatments. The mean values of volumetric water content during the growing season for the FR, F, R and C treatments were 24.8, 23.8, 18.0 and 17.1 percent, respectively. The results indicated that plastic mulch had substantial impact on retaining the soil moisture by reducing evaporation from the soil surface and the treatments with plastic mulch on the bed of the furrow (FR, F) had the highest soil moisture in comparison to the other treatments. Water productivity for dry matter of the FR, F, R and C treatments was 4.5, 4.4, 3.6, and 3.0 kg/m3, and for fresh matter of the FR, F, R and C treatments was 7.6, 7.4, 5.7, and 4.7 kg/m3, respectively. Based on the results, using plastic mulch on the furrow bed is recommended in order to reduce water loss and increase water productivity in furrow irrigation. Considering the effect of plastic mulch in maintaining soil water content, it is also recommended to utilize this method with the deficit irrigation method. Economic aspects should be taken into consideration in the future research on this topic.