Development of the low cost management technique for farmland resources conservation

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(1)Vegetation changes in abandoned paddy fields : We surveyed vegetation changes in abandoned paddy fields and clarified that the following three factors affect successional patterns as well as fallow durations ; geomorphological and hydrological conditions, vegetation types surrounding paddy fields and management regime such as plowing and irrigation. Based on those results and estimation of vegetation changes on a regional scale, we suggested the importance of developing management guidelines for conservation of both biodiversity and agricultural land resources(2)Change of soil physical properties of abandoned paddy fields : We studied on change of soil physical properties of abandoned paddy fields in Oshima village, Niigata prefecture as the years roll on. We conclude that the abandoned paddy fields 1)return to soil condition before reclamation, 2)have similar bearing capacity of hard pan of wet type them. Moreover micro-geography affects water content of cultivation layer. Hence te … More mporal management, i.e., cultivation, would be useful to sustain soil physical condition of plow layer/hard pan at the abandoned paddies, particularly in wet type.(3)Rational restoration system of abandoned paddy fields ; We considered about the relation between the vegetation of abandoned paddy fields into which trees invaded and the secular change of restoration cost of abandoned paddy field. Trees' invasion forms differed greatly between the wet farm land and the dry farm land. It was admitted that conditions, such as a disturbance, stress, and competition, had compounded the form of invasion. Moreover, restoration cost of abandoned paddy field was presumed based on the measurement experiment of the work concerning trees' felling, taking out, and processing. Moreover, the total cost was calculated based on aging of restoration cost of abandoned paddy field, and it was shown that annual continuous weeding management is the most economical for maintaining the producing function of abandoned paddy field.(4)Management system of abandoned or fallow paddy fields : We examined the generating mechanism of degrated farmland in former Higashi-kubiki-Gun Niigata Pref., and it was shown clearly that mechanical factors acted in early stages and the incitant factors acted strongly after the 1970s. Furthermore, desolationized advance was predicted paying attention to the labor force, and it was shown that 50 to 60% of farmland may be abandoned over the next 20 years. Moreover, the simple land suitability classification technique was developed based on the relation between management subject formation of farmland resources and resource state. In addition, the management survey of the fallow paddy field was performed and the conditions of the summer fallow cultivation enforcement which leads to reduction of extensive chemical herbicides use were examined. Moreover, the infrastructure improvement system corresponding to deep flooding management effective for weeding out and the control-of-maintenance system by pasturage of a cultivation abandonment rice field were examined. Less