Research On The Building Method Of Irrigation Prescription Map For Precision Production Of Wheat

We have scare water resources in our country,the per capita share of water in China is far below the world average.But we have to use a large amount of water for irrigation to solve the question of food for the country which has the largest population.The waste of water in irrigation is very serious in our country too,whicn make the utilization very low.In order to alleviate pressure that the shortage of water bring us,we have to change the unreasonable irrigation methods,and carry out water saving irrigation.Since different regions are effected by the different landform, soil characteristic and water table, the soil moisture in these regions are of great difference. Though the farm is not so broad, there is also a big difference among the plots, there must be waste of water to irrigate using average quantity of water,obviously,we can reduce the waste by irrigating according to the actual water demand of each plots in farm.We need the water demand information of all plots before variable irrigation,and the prescription map will provide this to guide the variable irrigation.Spray irrigation is a water saving irrigation method because there is no water loss in transportation,it can save about half of water compared to surface irrigation.With the theoretical basis of variable irrigation,the study provide a method to build prescription map for mobile spray irrigation.Prescription map is base on the water data by field test,import the water data of soil into prescription map building system to create map files,input the data of evapotranspiration,rainfall and so on,compete the soil moisture of each sampling point when irrigation by water balance model then interpolate,determine the soil moisture which is suitable for wheat according to soil type,wheat growing period and same other datas,after benefit analysis we can get the irrigation prescription map.The data of soil moisture can be measured by moisture sensor,the measurement is simple and convenient,the only shortcoming is that there are some errors,we can reduce the errors by calibrate the sensor base on the soil be measured.The prescription map building system was developed with platform of Visual C++ 6.0 with the geographic information system control MapObjects2.4 embeded to it,the system offer functions such as map analysis,spatial query and prescription map building.We can not only save the water,but also create a suitable growth environment for wheat by irrigating according to the guidance of prescription map.