Conservation tillage and irrigation metods effect on the water use efficiency in the wheat-corn rotation

In this research, effect of tillage and irrigation methos on the soil properties, crop yield, and water productivity (WP) was evaluated in wheat-corn rotation. The study was conducted in the form of a split plot experimental design with nine treatments and three replications in Marvdasht plan in Fars Prevance. Main plots were irrigation methods including surface irrigatin, drip irrigation (tape), and sprinkle irrigation. Tillage methods including zero tillage (direct drilling), reduced tillage, and conventional tillage (control treatment) were considered as sub plots in this research. Treatments were applied in plots with dimensions of 20 by 6 m and local corn and wheat varieties (704 and Chamran) were planted in the plots. Soil bulk density, soil infilteration rate, water consumption, crop yield, and water use efficiency were measured in different tillage and irrigation treatments. Collected data were analyzed using SAS software and Duncan's multiple range tests were used to compare the treatments means. Results showed that drip irrigatin had the lower soil bulk density compared to the other irrigatin methods. Soil bulk density was also lower in the reduced tillage method compared to zero and conventional tillage. The maximum infilteration rate occurred in the tape irrigation among irrigation methods and the minimum infilteration rate was related to the surface irrigation. Reduced tillage had the highest infilteration rate and the zero tillage had the lowest one. Tillage and irrigation methods had no significant effect on the wheat and corn yield in the first year; while in the second year, wheat yield was affected by irrigation and tillage methods, and corn yield was affected by the tillage methods. In both crops (wheat and corn), drip irrigatin metod had the higher yield compared to the sprinkle and surface irrigation methods. Wheat and corn consumed the largest water volume in the surface irrigatin method and the least water consumption in these two crops was related to the drip irrigation. Tape irrigation saved water in wheat growing compared to the sprinkle and surface irrigation for 38 and 77%, respectively. These water savings in corn growing were 54 and 135%, espectively. Irrigation methods had a significant effect on the water productivity of wheat and corn; whereas, water productivity was not affected by tillage methods in the first year. The maximum water productivity was obtained from the tape irrigation in both crops and the minimum water productivity was related to the surface irrigation.