Experimental Study on the Recoverability of Plow Sole in a Cracked Paddy Field

• Main Authors: Cheng, Shih-Wei, 鄭世尉
• Other Authors: Liu, Chen-Wuing
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/26319339601489016474

碩士 === 國立臺灣大學 === 農業工程學研究所 === 89 === Taiwan’s paddy fields currently is facing the negative impactions on the government policy of releasing the farmlands. To preserve the acreage of paddy field, its ecological function of the groundwater recharge become more important than the traditional rice production function. In general, the existence of plow sole (impervious hardpan layer) can prevent water infiltration and reduce the amount of the groundwater recharge rate. When rice paddy has been harvested, after a period of drainage and exposure to sun light, the paddy field surface may crack into fissures. If precipitation or overflow is applied to the paddy field, the rate of infiltration can be improved tremendously. For quantitative simulate the infiltration from the cracked paddy field, an laboratory soil column experiment is designed. Various conditions including different soil texture, ponding water depth, fissures width and depth are investigated to evaluate their effects on the temporal infiltration curves and the rehealing mechanism of the plow sole. Results of the experiments shows the existence of the fissures increase the infiltration groundwater recharge. Particle-size distribution analysis shows that the soil particles which has been deposited to the fissure surface by cake filtration mechanism and hence decrease the infiltration rate. Other experiential set results indicate that the depth of overflow water, soil structure and plow effect also affect the recoverability of the plow sole. When ponded water depth increase, the pressured water with suspended clay particle deposit on the fissures space and improves the rehealing effect. Soils with low volumetive density change its structure easily as water infiltrates. It will also disperse the clay particle from the surface, redeposited on the fissure surface and gradually decrease the infiltration rate. Plowing the surface soil can also enhance the recoverability of the plow sole .