The production ratio of cultivated crops became lowered along with the increase of production cost due to oversupply from the reduction of rice consumption, poor agriculture scale, and high farming land price. Also, there was a serious increase of the occurrence of idle land of fallow due to poor labor power and farming conditions. This study was aimed to analyze the component hurting the production of rice field as well as the effective use of rice fallow, and to enhance the effect of rice production adjustment when there is an intended fallow on assumption of restoration.

The NO₃-N concentration of soil of restored rice field was higher than that of non-fallow of rice immediately after fallowing, and it decreased to 3.25mg/kg after restoration. The CEC level of fallow rice field increased 1.69cmol/kg before fallowing along with the increase of CEC level. As for the change of soil by alternative crop, the NO₃-N concentration and CEC gradually decreased in a bare land, and increased in the land of cultivating alternative crops. Also, it increased most in the land of cultivating crops for food. As for crops for landscape, the productivity was higher in buckwheat than rape when the land cultivation was stopped for 1~2 years, and as for crops for forage, it was higher in  sorghum×sudangrass than rye. When compared with the cultivation of rice, sorghum×sudangrass earned about 72% of the profitability of rice, and it was followed by buckwheat (62.6%), rye (53.2%), and rape (48.7%) in order. As for the productivity after it has been restored for 1 year since fallow, the rice productivity was the highest by posting 747.5kg(based on grain yield) of crops for food. Then, it was followed by crops for landscape, crops for forage, and bare land.