Study of the measurement to preserve agricultural field as tertiary nature with the aim of coexisting the natural environment

在日本的农村地区，为了平衡农业耕作，保持了丰富的自然环境，即“第二自然”。然而，一些农业领域最近被集中管理，以保持高生产力，同时严格保护环境作为生物小区。这种密集型场可被归类为“第三性”。本研究旨在通过野外调查研究两种环境的平衡和变化。2003年，在花卷市花轮津美沼泽区附近的野生鸢尾花田设置了第一个试验点。2004年，工厂搬迁至岩泽平原的Hannnoki池塘。第二个场地由面积为1公顷的小型农场池塘和周围未开垦的潮湿低地组成。因此，在该地区开发的政府项目旨在将稻田土地整理作为“第三自然”，将湿地保护作为“第二自然”。岩手大学的四名研究人员完成了该项目的全部实地工作。藤井博士测量了现场和周围稻田土壤水分的时间变化，竹原博士探索了同一地点的植被特征。然后仓岛博士观察了气象和水文特性。此外，竹田博士还对农田耕作的机械能进行了研究，另外两名研究人员提供了支持我们活动的实地数据。我们在实地数据和热烈讨论的基础上，思考了“湿地作为第二自然”与“生产性农田作为第三自然”之间的生态关系。希望这些研究能对维持农田高生产力的能量投入进行定量研究。

In the rural area of Japan, ample natural environment, namely "secondary nature", has been maintained so as to balance agricultural cultivation. However, some agricultural field is recently managed intensively to keep high productivity with strict preservation of environment as a biotope. This intensive field may be categorized as "tertiary nature". This study aimed to examine the balance and change of both environments through the field works.In 2003,first test site was set on wild iris field beside Hanawa-tsutsumi swamp area in Hanamaki-city. Then site was moved to Hannnoki-pond in Isawa Plain in 2004. Second site is composed of small farm pond of 1ha area, and surrounding wet lowland uncultivated. Thus the governmental, project developed on this site aims both the land consolidation of paddy field as "tertiary nature" and the conservation of wet land as "secondary nature".Four researchers in Iwate University fulfilled the field works for the full term of this project. Dr.Fujii measured the temporal change of soil moisture of the site and surrounding paddy field, and Dr.Takehara explored the vegetation characteristics on the same location. Then Dr.Kurashima observed the meteorological and hydrological properties. Besides them, Dr.Takeda examined the mechanical energy to cultivate the field, and other two researchers supplied the field data to support our activities.On the basis of the field data and heated discussion, we considered the ecological relationship between "wet land as a secondary nature" and "productive field as a tertiary nature". We hope these academic works would lead to a quantitative examination on the input energy to keep agricultural field with high productivity.