Development And Validation Of Corn Nitrogen Nutritional Spectra Diagnosis Model

Corn in China’s grain crop occupies an important part, due to nitrogen on large amounts of soil and crop samples cost analysis greatly, thus resulting in a to soil and plant analysis as the basis for soil nitrogen precision management cost is very high. The use of hand-held active remote sensing spectrometer GreenSeeker and chlorophyll meter SPAD-502 to obtain the required time and cost of crop information is low, so the application of this method can promote the precision management of nitrogen in field crops.The application of GreenSeeker and SPAD-502 on chlorophyll meter under different nitrogen levels in the growth period of canopy normalized difference vegetation index(NDVI), test SPAD value of leaves and shoot nitrogen nutrition status, discusses the four maize growth period NDVI value, SPAD value, nitrogen dynamic change, correlation between NDVI and SPAD and with leaf nitrogen content and yield of Maize by non-destructive diagnosis, nutritional status and growth status of real-time monitoring and determination of nutrients in plant abundance in different nitrogen levels were measured under maize NDVI value to determine the optimal dressing parameters of the model, laid the foundation for the accurate diagnosis and monitoring of maize and, as the corn fertilization decision-making basis, to provide a theoretical basis for the reasonable application of nitrogen fertilizer and nitrogen management, so as to realize the variable fertilization.This paper is mainly for farmers blind excessive fertilization, on the basis of the corn in the growth period of fertilizer requirement characteristics and absorbing nitrogen rule premise under, access to canopy spectral information, which makes use of the corn canopy spectra of nitrogen nutrition diagnosis technology, respectively on maize growth period in the four periods(jointing stage, heading stage, grain filling stage, and mature stage) were NDVI and SPAD, including the determination of nitrogen content, nitrogen nutrition of real time fault diagnosis technology to carry out, achieve reasonable fertilization, variable rate fertilization requirements. To this end, do the following aspects of the research work:(1)the test by different growing periods of corn canopy NDVI and plant ceiling between nitrogen were significantly positive correlation, the effect of exponential function fitting to function was better than linear and decision coefficient between 0.726, 0.874, which jointing correlation reached the highest 0.874, that the choice of jointing NDVI value the amount of nitrogen application in the model is feasible salinity and maize plants. Under basal conditions or dressing conditions, grain and straw containing nitrogen were the highest nitrogen N4 treatment reached the maximum value, increases with the increase of nitrogen fertilizer application, Maturity Maize Grain and straw containing nitrogen and fertilization are positive correlation no matter of. Under the condition of top dressing, than the base fertilizer, grain containing nitrogen were increased by 3.35%, 9.28%, 5.38%, straw nitrogen content were increased by 5.13%, 3.85% and 6.33%; at the same time, the grain contained nitrogen higher than straw nitrogen content, finish explaining maturity nitrogen mostly translocated to grain, in order to improve the yield and quality of maize.(2) in the experiment 2, the nitrogen uptake of maize was significantly increased by the validation of the model in 2015, but the efficiency of N use efficiency decreased with the increase of N application rate. Compared with the control, reduction of nitrogen fertilizer to improve maize yield and nitrogen utilization rate, and access to the good economic benefits, have good reliability and practicality is a has good corn nitrogen control technology, and has broad application prospect.(3) according to the differences in the area between the crop nitrogen nutrition status, combined with canopy spectral characteristics value of variable rate fertilization of corn, in the vigorous growth of multi regional fertilization, in the region of poor growing less fertilizer, the ultimate trend as a result of fertilizer application and target yield is consistent, so as to better guide the fertilization, optimize nitrogen.