Precision  fertilization is one of the important measure in precision agriculture. In the agricultural management to implement "demand input" and change uniform input into a variable.   According to soil conditions  and  crop status comprehensive  to variable-rate fertilization.  The core of precision fertilization is to get the largest fertilizer efficiency . In this study, we carried out precision fertilization  of wheat through the topdressing by intelligent spatial decision , which is  based on the variability of soil fertility which  soil nutrient supply and target yield in the whole growth period as the variable- rate nitrogen  making and  growth status of wheat  as variable- rate nitrogen top-dressing making to set up in  precision rate fertilizer applicator.

 The results showed that the yield coefficient of precision fertilization  had a decrease of 1.08-1.23 percentage points; According to soil supplying  nutrient  and target  yield to recommended fertilizer ,can save fertilizer 9.82% compare to farmer’s. Suitable nitrogen decision- making could increased yield 5.2-19.8% compare to farmer’s. The Nitrogen rate not only impact on  the nutritional status of wheat£¬but  also leaves colors. Using the  Greenseeker  to test wheat canopy NDVI.  Result showed that  with the increased of nitrogen fertilizer NDVI value increased During the jointing  stage ,  nitrogen and  NDVI values have a relation , Correlation coefficient is 0.59.  Within a certain ranges, the more  fertilizer, the more  NDVI value ,but  when the fertilizer over certain mount, NDVI value is not increased again.

Along with the development of science and technology, new sensor will be more and more used at variable-rate fertilizer in the future. Rapid  and non - destructive measurement will be  development  and application in the future.