| Nowadays,under resources is becoming more deficient,irrigation water volume in agriculture can not be added,whereas , crop yield production need to be increased,how to optimally allocate the limited irrigating water at the different growth stage of crops and how to irrigate the crop accuracy to get maximal benefit and become a lot of research in the agricultural irrigation field. For example of the Shiyang River Basin along the Hexi Corrider,in Gansu province,made the imitial research of the major crop water production function and irrigation schedule optimal model,the results are following: 1)Based on the related experimental datum gathered,drawing the relationship curve of several major crop yield and evapotranspiration,such as spring wheat,spring wheat-corn strip field,seed melon,sweet melon,cotton and flax and so on. The result shows these there:linearity and non-linear between crop yield and evapotranspiration. The yield increased as the ecapotranspiration,while it comes to a certain,the yield won't increase,it may decline. 2)According to the non-full irrigation experimental datum of spring wheat and flax in Liangzhou and Gulang city of Shiyang River Basin,calculating the crop water deficiency sensitive index or coefficient by using crop water production function models of Jensen,Blank,Stewart and Minhas. The result shows that: The variation rhythm of the sensitivity index (coefficient) changed unanimously for Jensen,Blank and Stewart water production functions of spring wheat in Liangzhou city,the volume is small in the former stage,then become large at the middle stage,and less at the last stage. Jensen and Stewart water production functions are better of spring wheat in Gulang County in 1987-1989. The Variation rhythm of water deficiency sensitive index is unanimous: the volume are small at first,then large at middle,and diminish at last. The Variation rhythm of water deficiency sensitive index is unanimous in Jensen,Blank and Minhas of flax in Liangzhou county in 1987-1989. The water deficiency sensitive index(deficient) in Gulang district in 1987-1989 models bad,are too many minus. 3) Establishing the non-linear model to definitive the irrigation quota and dimension of single crop,according the three prototype Precipitation,allocating the limited water optimally according to full water supply,95 percent,75 percent and 50 percent. Economy benefit is the biggest aim function,so getting three groups for irrigation quota,irrigation dimension and benefit,the biggest benefit is the most optimal result. As see it from the three correspond irrigation area and irrigation quota calculated under the three frequency,the optimal results of spring wheat and cotton are obtained at the first frequency,and then the third frequency,the twice worst. In Gulang,under the three frequency,the optimal result is obtained at the first frequent,then the twice,the third is worst. While under the same condition of supplying water,the difference of the irrigation quotas at three frequencies are small,the irrigation area decline with the rainfall frequncens of 50 percent, 75 percent and 95 percent,under the condition of the water supplying,the irrigation quota remains the same at the same rainfall frequnence,the irrigation area declines gradually according to the water suppling of 100 percent,95 percent,75 percent and 50 percent. 4) Establishing the optimal allocating model of crop in the procreating stage in Shiyang River Basin,dynamic programming model,allocating the limited water in crop increment stage,and portraying the relating curve between the water supply and relative yield. Comparing the results with the experimental datum shows that the optimal work well on model the crop water allocating,it can come to the aim of water-saving on the basis of yield increase or no big varintum.
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