Extracting winter wheat planting area based on cropping system with MODIS data

Winter wheat is one kind of important crop in China. Its planting area is one key element to explain yield change. To obtain winter wheat planting area as soon as possible can provide scientific reference for our country to make related policy. Based on the cropping system in Shandong Province, winter wheat is divided into two kinds “winter wheat sowed by machine-maize” and “labour broadcast winter wheat-rice”. Using MODIS data, NDVI characters of winter wheat, garlic, greenhouse vegetable, from sowing till overwintering stage were analyzed. Together with NDVI characters of former stubble crops in middle September, extracting requirements were set up for winter wheat planting area which was sown by machine this year. In view of the spectrum similarity between rice wheat and greenhouse vegetable from sowing stage till overwintering stage, rice wheat planting area of former year was extracted relying on the character of biomass rapid growth at jointing stage. Because of the “labour broadcast winter wheat-rice” cropping system is very fixed in Shandong Province, then the rice wheat planting area of former year can take the place of the rice wheat planting area this year. Two kinds of winter wheat area were merged, and tested by 284 groups of located spots data, with the accuracy reached 94.01%. It is feasible to extract winter wheat area before overwintering stage, and the time is 4 months earlier than using jointing stage NDVI.