Determination of Wheat Optimal Irrigation Depth on the Base of Different Management Strategies in Center Pivot Irrigation

In irrigation scheduling, one question is “how much is the optimal depth?”. In this study the optimal irrigation depth (by assuming the power distribution function and by taking into consideration the distribution function, which governs the data (normal distribution)) by considering the environmental effects was determined for three water management strategies (i. e. unlimited, limited nitrogen leaching and environmental protection) for wheat under center pivot irrigation system. The System layout in 32 hectare field was installed according to the ASAE standard. Four radial lines of catch cans were used at intervals of 6m (two radial lines of catch cans A and B, were installed on the maximum slope with 3˚ between every two rows and two radial lines of catch cans C and D, were installed on the minimum slope with 3˚ between every two rows). The field data were collected by the five different speeds of the center pivot system. The economical ratio (C) for three water management strategies were 31.19, 4.58 and 1.45, respectively. The optimum irrigation water was calculated for the three different management strategies. The results indicated that the lowest value of optimal irrigation depth was observed under the unlimited strategy, and the highest value of optimal irrigation depth was found for the environmental protection strategies (both with assuming power distribution and normal distiribution function).