Field detection of non-use paddy fields at Miyagi Prefecture in Japan using satellite and GIS data

According to the 2000 Census of Agriculture and Forestry in Japan, the non-use paddy fields are increasing every year. The non-use paddy fields are abandoned paddy fields or fallow paddy fields. The amount of non-use paddy fields reached about 488,000ha in 2000. Especially at hilly and mountainous areas, there are many non-use paddy fields. We want to more exactly understand this situation of Japanese agriculture from the perspective of remotely sensed data in order to maintain the productivity and multi-functionalities of agriculture. We researched in Miyagi Prefecture, northeast Japan. We used 5 scenes Terra/ASTER images taken on April 17, June 4, September 1 and 24, and November 20, 2001. In this study, we researched spectral characteristics and NDVI changes at arable lands with ground truth data and a topographical map. We analyzed spectral characteristics of crops and non-use paddy fields, and made thresholds about each category to detect the land use. Using these thresholds, we constituted a decision tree and made a land use map. We examined this map and grasped Japanese agricultural state. The estimated areas of non-use paddy fields that are made in this method are higher than the statistical data. It seems that there are two reasons of this result. One reason is that the classified area of non-use paddy included mixel data and other categories. The other reason is that statistical data is different from the real state of arable lands. In this case, non-use paddy fields are more spreading than statistical data and remote sensing is potential method of detection of non-use paddy fields.