Spatializing regional fertilizer input based on MODIS NDVI time series

Regional agricultural ecological system faces more and more environmental pressure with bigger fertilizer input and higher land and water resources use efficiency. In order to assess the environmental risk of fertilizer overuse, the spatial data of fertilizer input is necessary. This paper firstly analyzed the structures of land primary productivity and the major limiting factors in theory, then adopted principal component analysis to quantify the spatial relationship between the 8-day composite MODIS NDVI time series of different cropping patterns and regional land natural quality, also its relationship with fertilizer input, finally designed the spatializing method of the regional statistical fertilizer input. The results showed that the first principal component of the 8-day composite MODIS NDVI time series under different cropping patterns was closely correlated with land natural quality, and their second principal component significantly related to chemical fertilizers input. Therefore, this paper spatialized the community-level statistical chemical fertilizer input in proportion with the second principal component, and concluded that the principal component analysis of the 8-day composite MODIS NDVI time series under different cropping patterns could discern the productivity disparity from land quality and human beings inputs such as fertilizer input, thus the rationality and feasibility of the spatializing method were clarified .