Study on mechanism of change/collapse in a tillage renouncement rice field, and its strategy for antidisaster and land use

Research Project

Project/Area Number	07456108
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Research Field	Irrigation, drainage and rural engineering/Rural planning
Research Institution	Tokyo University of Agriculture
Principal Investigator	NAKAGAWA Shoichiro Tokyo University of Agriculture, Faculty of Agriculture, Professor, 農学部, 教授 (20246664)
Co-Investigator(Kenkyū-buntansha)	MASUDA Shin-ya Tokyo University of Agriculture, Faculty of Agriculture, Lecturer, 農学部, 講師 (50078218) NARIOKA Hajime Okayama University, Faculty of Environtal Science and Technology, Associate Professor, 環境理工学部, 助教授 (70211448) KOMAMURA Masaharu Tokyo University of Agriculture, Faculty of Agriculture, Professor, 農学部, 教授 (60078194) OGURA Chikage National Institute of Agricultural Engineering, Laboratory head, 研究室長穴瀬真東京農業大学, 農学部, 教授 (80015619)
Project Period (FY)	1995 – 1997
Project Status	Completed (Fiscal Year 1997)
Budget Amount *help	¥6,600,000 (Direct Cost: ¥6,600,000) Fiscal Year 1997: ¥1,600,000 (Direct Cost: ¥1,600,000) Fiscal Year 1996: ¥2,500,000 (Direct Cost: ¥2,500,000) Fiscal Year 1995: ¥2,500,000 (Direct Cost: ¥2,500,000)
Keywords	tillage renouncement / slope-land paddy field / land condition / paddy field facilities / plant succession / landslide and collapse / land use measure / protection against disasters
Research Abstract	Under the conditions concerning the agriculture and the farm village in recent years to be severe, at the inside ravine place paddy field of Japan, the tillage renouncement is moving ahead rapidly and a lot of interests are moved from the viewpoint of the area promotion and the country preservation. In this study, it made a tillage renouncement paddy field area in Nagano Prefecture a fixed point observation area simultaneously with analysis in the whole country eyesight. It examined about the following item. (1) Paddy field (ridge, flume, drain, reservoir, road between fields and so on). (2) The paddy field soil and soil profile (plow layer, plowsole, subsoil). (3) The investigation and analyzes the mechanism of change, transfer and collapse which accompanies tillage renouncement such as the weed invasion like passing years. It examined the measure of new protect on against disasters and preservation and state of land use based on the result. In the field investigation, it implemented abou … More t each of the following items. (I) By the aerial photography by the balloon, it did the landform of the shelf rice paddy and repartition at the tillage paddy field and the renouncement paddy field. (ii) It measured a volume water content in plow soil layer with TDR. (iii) With stick-auger, it measured the natural moisture content from plowsole to subsoil layer. (iv) By the frame investigation method, it calculated the multiple priority of ground plants and it did the investigation of the vegetation distribution. (v) It classified vegetation with high priority rate into the dry plant, the wet plant and the middle plant with the dormant type. (vi) It measured the distribution of soil layer structure and the bearing capacity of field by the use of the cone-penetrometer method and stick-auger method. (vii) The aerial photograph that the photography time depends on the purpose to chase the passing year change of the landform was analyzed. (viii) By the tensiometer method, it measured change of soil moisture content in field. As a result, there was a tendency with the more soil moisture quantity in plow soil layer and plowsole layer. The cut part of terrace tended to get to undergo influence by underground water compared with the mound part of terrace. As for the wet and dry condition of surface soil, it found that there was correlation in the paddy field soil types such as the move of underground water, the soil layer structure, the soil layer hardness. Also, there were an area and an independent priority area which the priority species of the plant intermingles with and there were both of dryness and wetness plants succession. It found that there was correlation, too, with the ground moisture quantity and the invasion weed could fix an index plant by up and down with underground water level. Moreover, it ordered the characteristic of the form and the distribution of the rootstock of the appearance priority species. When the tillage renouncement continued, that the rootstock of the dry plant approached the dry part of ground and promoting the collapse of the ground structure were suggested. Less