Development of the low cost management technique for farmland resources conservation

(1)弃耕稻田植被变化：调查了弃耕稻田的植被变化，明确了影响退耕演替格局和休耕持续时间的三个因素：地貌和水文条件、稻田周围的植被类型和耕作灌溉等管理制度。基于这些结果和对区域尺度上植被变化的估计，我们提出了制定生物多样性和农用土地资源保护管理指南的重要性。(2)弃耕稻田土壤物理性质的变化：研究了新泻县大岛村弃耕稻田土壤物理性质随时间的变化。我们得出结论：1)弃耕稻田恢复到开垦前的土壤条件，2)湿地型稻田具有相似的硬盘承载能力。此外，微地理还影响着耕作层的含水率。因此，TE…(3)合理的弃耕稻田恢复体系，考虑了树木入侵后弃耕稻田植被状况与弃耕稻田恢复成本长期变化的关系。湿地和旱地的树木入侵形式有较大差异。人们承认，干扰、压力和竞争等条件加剧了入侵的形式。通过对树木采伐、取出、加工等作业的测量实验，推算出弃耕稻田的恢复成本。此外，根据废弃水田恢复成本的老化计算了总成本，结果表明，维持废弃水田的生产功能，每年持续除草管理是最经济的。(4)废弃或休耕水田管理制度：考察了原东新泻退化农田的产生机制，明确了机械因素在早期作用，激励因素在20世纪70年代以后作用较强。此外，还预测了关注劳动力的荒漠化进程，结果表明，在未来20年内，可能有50%至60%的农田被遗弃。根据耕地资源管理主体构成与资源状况的关系，建立了简单的土地适宜性分类方法。此外，还对休耕稻田进行了管理调查，并对减少化学除草剂广泛使用的夏季休耕耕作实施情况进行了审查。此外，还研究了与深水淹治理相对应的有效除草的基础设施改善体系和弃耕稻田的放牧控制维护体系。较少

(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