Optimal Distance of DripTapes and Water Productivity of Wheat in LoamySoil Texture

For wheat crop irrigated with drip tapes, water productivity, optimum tape spacing and soil salinity are issues which are important in terms of agricultural economic and soil sources sustainability. For this purpose, an experiment was conducted on a loamy soil texture to study the effect of drip tape spacing on wheat yield and its components, water productivity and variations in the soil salinity. A randomized complete block design consisting of four treatments; three drip tape spacings (45, 60, and 75 cm; denoted by A, B, and C, respectively), and a basin-irrigated treatment (as the Control; represented by D) was carried out on a loamy soil for two years from 2017 to 2019 in Mahyar area of Isfahan Province. The treatments were replicated three times. The volume of applied water for treatments A, B, and C was identical in each irrigation event, whereas the amount of applied water for treatment D was similar to the farmer method. The result of composite variance analysis revealed that the treatments had a significant effect on grain and biological yield at 99% level of confidence, but they did not have any significant effect on water productivity and harvest index. The average water productivity for treatments A, B, C, and D were 0.72, 0.71, 0.66, and 0.64 kgm-3 respectively. The maximum yield was found for treatment D. During the two years of testing, the soil salinity in the tape treatments was significantly increased, but it did not change in the basin irrigation. Considering that the all three tape irrigation treatments were placed statisticaly in a common group, therefore the 75 cm-tape distance is recommended for loamy soil texture.