Effect of Tillage Method, Residue Retention, and Different Levels of Irrigation Water on Yield and Water Productivity of Wheat in Cold Region of Khorasan Razavi

In order to study yield and water productivity of wheat in common cropping rotation (wheat-sugar beet) in cold regions, a research was conducted in Jolge-Rokh Research Station, Khorasan Razavi Province, Iran. The experiment used split-split plots in randomized complete block design (RCBD), with three replications, and was conducted during 2013-2016. Treatments were tillage methods (conventional tillage, minimum tollage, and no tillage) in the main plots, residue management (no residue, and leaving 30% and 60% residue) in sub-plots, and irrigation water levels (50%, 75% and 100%) in sub-sub plots. Results of analysis of variance showed that various tillage methods and residue management had no significant effect on yield and water productivity, but effect of irrigation water levels was significant (P<0.01). Yield in 75% and 100% water treatments was 4751 and 4961 kg/ha, respectively, with no significant difference. However, yield at 50% water consumption was about 3574 kg/ha, which was significantly lower than the other treatments. Water productivity in 50%, 75% and 100% water use was 1.067, 0.960, and 0.875 kg/m3, respectively. The highest wheat yield (6331 kg/ha) was obtained from minimum tollage with 30% residue and 100% of water level. The highest water productivity of wheat (1.173 kg/m3) was obtained in no-tillage, 30 present residue, and 75% of water use. Water productivity of no tillage treatment+60% residue and 50% water use, and conventional tillage treatment+ no residue and 50% water use were in the second and third place with values of 1.136 and 1.132 kg/m3, respectively.