Selection of available weedy plants as a cover plant on slope and their function of soil erosion prevention.

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 15380166
• 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: OKAYAMA UNIVERSITY
• Principal Investigator: ADACHI Tadashi Okayama University, Graduate School of Environmental Science, Professor, 大学院環境学研究科, 教授 (20012007)
• Co-Investigator(Kenkyū-buntansha): OKI Yoko Okayama University, Graduate School of Environmental Science, Professor, 大学院環境学研究科, 教授 (30127550) ; NAGAI Akihiko Okayama University, Graduate School of Environmental Science, Professor, 大学院環境学研究科, 教授 (80093285) ; CHIKAMORI Hidetaka Okayama University, Graduate School of Environmental Science, Associate Professor, 大学院環境学研究科, 助教授 (40217229) ; NAKASHIMA Yoshitaka Okayama University, Graduate School of Environmental Science, Assistant Professor, 大学院環境学研究科, 助手 (50304340)
• Project Period (FY): 2003 – 2006
• Keywords: Slope land / Cover plants / Life form / Soil erosion / Water erosion / Surface runoff / Action of soil formation / Neutralization effects of acidity of rain

Research Abstract

From a viewpoint of the difference of the life form of a cover plant, we evaluated the effect which the life form of a cover plant on slope exerts on soil erosion prevention. It measured the surface runoff and the soil loss for every rain on slope composed of Masa soil with 10 inclinations, which the introductory board and water tank were installed in the lower end of the examination frame of 2m (W) x 5m (L). We set up five plots. Four of these plots were a cover plant plots vegetated with Cynondon dactylon Pers., Dichondra repens Forest and Artemisia princes Pampan, from which it is thought that the adaptation power to severe environment is high, and a life form differs. The other one was a bare surface plot as a control plot. The obtained results were as follows.
(1)The dangerous rainy season is in May-November. Even when it is little year precipitation, if the frequency of rain such as more than 3mm/lOmin is high, the amount of soil loss increased.
(2)Although the amount of soil loss of a bare surface plot was the full limits of the maximum permissible dose of our country, in a Artemisia princes plot and Cynondon dactylon plot, it is the amount of soil loss below the maximum permissible dose. Therefore the effect of a cover plant on the soil erosion prevention on slope was able to check and quantify it. Among the species, Artemisia princes, straight life form, was excellent. This tendency was also the same of the following phenomena.
(3)It was shown clearly that increase of the amount of penetration of rain into soil and reduction of surface runoff occurred because of increase of the soil vacancy by the root system and also increase of the soil coarse vacancy by formation of soil aggregate due to humus.
(4)CEC of soil increased with increase of humus, and there are the further development of soil structure and an effect of improving soil environment to the suitable habitat for growth of a cover plant.
(5)The pH neutralization effect of the acid rain by a cover plant was accepted, and not only the soil erosion prevention effect but the effect which mitigates the influence of the ecosystem on air environment deterioration has been checked.