Nitrogen Diagnosis And Decision Of Winter Weat Considering A Non-Uniform Vertical Nitrogen Distribution

For China,the agriculture has been in the development of “high-yield?surplus grain?high quality”,the state of “low yield?inferiority?cheap”has been changed.However,there have been a lot of problems about farmland ecological environment?farmland soil quality?farmland groundwater.So,the sustainable development of the farmland are attracting more attention while we obtained abundant harvest for many years.“ Double-cut”—— less fertilizer and pesticide,policies of“zero increase”even “negative growth”had been given.So,what we need not only the high yield? quality ?benefit,but also the sustainable development of the farmland.The remote sensing technology has been used in agricultural production for large area?accurate and continuous monitoring,by the advantages of fast,efficiently and real-time.The knowledge of agriculture and the remote sensing technology has been put together,to build the motion of “sky—ground”,by the method of ground hyperspectral Remote Sensing and satellite multispectral Remote Sensing.First,we focus the non-uniform vertical of winter wheat canopy and the prediction nitrogen content of the winter wheat from the different layers.Then,diagnosing of nitrogen nutrition in winter wheat nitrogen distribution.The last,building the prescription map of nitrogen fertilization,by satellite multispectral Remote Sensing of the field scale.The main conclusions:(1)The non-uniform vertical of winter wheat canopy nitrogen contentThere were some differences of non-uniform vertical of winter wheat canopy nitrogen content from different growth periods by considering the nitrogen content of leaf position.During the jointing stage?flowering stage?filling stage,nitrogen content in each layer showed a decreasing trend from top to bottom layer by layer.During the flag-picking stage,the nitrogen content in each layer of winter wheat canopy increased first and then decreased,with the second layer reached the highest value.The ratio of nitrogen content from the upper layer in the whole layer during each growth period was > 1,and it was very significant with the total leaf nitrogen content(TLNC).During the jointing stage,for the LNCu1?LNCu2?LNCu3,the r was: 0.94?0.99?1;During the flag-picking stage,for the LNCu1?LNCu2?LNCu3?LNCu4,the r was: 0.79?0.96?0.98?0.99;During the flowering stage,for the LNCu1?LNCu2?LNCu3,the r was: 0.74?0.88?0.98;During the filling stage,for the LNCu1?LNCu2,the r was: 0.94?0.98.By the non-uniform vertical of winter wheat canopy nitrogen content,by relevant agronomic mechanism and calculation deduction,by the contribution ratio of each layer to the nitrogen content in the whole layer was fully considered,a model was developed to estimate the total NC of the whole winter wheat canopy based on the non-uniform vertical of winter wheat canopy nitrogen content.(2)The TLNC Estimation of Winter Wheat Based by Hyperspectral and Vertical Distribution of NitrogenThe prediction model of nitrogen content was established based on the vertical distribution of nitrogen in winter wheat and the optimal vegetation index.The winter wheat canopy nitrogen content was realized by remote sensing estimation of validating the ground hyperspectral data of winter wheat from the year of 2013 to 2014.The results show that: Based on the estimation of leaf nitrogen content based on the vertical distribution of nitrogen,the values of R2 and n RMSE of the three vegetation indices based on GI are 0.61% and 8.84% respectively.The R2 of the model based on m ND705 is 0.59,and the n RMSE is 8.89%.The R2 of the model based on NDVI was 0.53,and the n RMSE value was 9.37%.The inversion model has high accuracy and reliability.(3)Diagnosis of Nitrogen Nutrition in Key Growth Stages of Winter Wheat Based on Nitrogen Nutrition IndexThe critical nitrogen nutrition index of winter wheat was further determined by constructing the critical nitrogen concentration dilution curve of winter wheat through four nitrogen application levels of several winter wheat varieties.Finally,the diagnosis of nitrogen deficiency-excess degree of winter wheat was realized.The results showed that the biomass of winter wheat increased with the increase of nitrogen application,and the nitrogen content of winter wheat decreased with the development of ZSstage.The critical nitrogen concentration dilution curve of winter wheat conforms to power function relationship: y = 5.39 * ZSstage-0.19,where R2 = 0.43.The model is validated by RMSE = 0.24%.Based on VND-TLNC monitoring critical nitrogen concentration in winter wheat,the nitrogen nutrition index model(NNI)was established,which provided a basis for diagnosis of nitrogen nutrition in winter wheat.(4)Prescription Map of Nitrogen Fertilizer for Family FarmsEstablishment of winter wheat nitrogen content(TLNC)model based on satellite remote sensing data,TLNC=(6.51*MTVI+1.19)/?,R2=0.39,RMSE=0.45%?Modeling and validation of TLNC based on vegetation index MTVI and TLNC based on 2018 test data,TLNCc=5.39*ZSstage-0.19,R2=0.39,RMSE=0.11;The data of 2017 were brought into the model to validate,R2=0.61,RMSE=0.10?According to the relationship between NNI and vegetation index MTVI,the fertilization prescription map was obtained by using ENVI and Arc GIS.Compared with the nitrogen nutrition index NNI constructed from ground hyperspectral data in Chapter 4,The recommended prescription of nitrogen fertilization based on satellite remote sensing image data can realize field-scale fertilization recommendation.Comprehensive nitrogen fertilizer prescription model and Planet satellite remote sensing monitoring provide nitrogen fertilizer recommendation for family farms.