Definition of Wheat Growth Management Zones Based On Remote Sensing and Geostatistics.

Normalized difference vegetation index (NDVI) data calculated from HJ-1 A/B CCD images (30-m resolution) of three different winter wheat (Triticum aestivum L.) growth stages, combined with soil nutrient indices, including total nitrogen, organic matter, available phosphorus, and available potassium, were used to define winter wheat growth management zones by cluster analysis in county level based on spatial variability analysis and principal component extraction. The results showed that integration of NDVI at heading stage and soil nutrient indices produced the best results of management zone definition with the coefficients of variation of NDVI and soil nutrient indices in each defined zone of 4.49%~6.06% and 3.25%~87.89%, respectively. However, those values were much larger when management zones were defined individually by NDVI or soil nutrient indices, which indicated that the newly developed management zone definition method could reduce the variability within the defined management zone and improve crop management precision, therefore contribute to winter wheat growth management and process simulation in region scale.