(37(1):58-67)Studies on the Methods of Soil Conservation on Slopeland for Summer Vegetable Production

本試驗設置於鳳山熱帶園藝試驗分所坡度11°（20％）東南向砂質壤土的坡地上。其目的在比較坡地夏季蔬菜園不同水土保持方法對水土流失控制效果，以及對土壤水分，土壤理化性和蔬菜生育之影響情形，以探求最經濟有效的水土保持方法，提供坡地夏季蔬菜園土壤管理及保育設計參考。本試驗包括一、內斜式平台增段；二、百喜草帶狀覆蓋及敷蓋；三、百喜草條帶及戀風草敷蓋；四、無處理清耕對照區等四處理。 （一）各處理水土流失測定結果均以百喜草條帶及戀風草敷蓋處理區較少，百喜草帶狀覆蓋及敷蓋處理區次之，內斜式平台增段處理區再次之，惟三者之問差異不顯著，而以無處理清耕對照區較多與其他處理區差異極顯著。 （二）各處理地表逕流水中養份流失量和水土流失量有大小相同之趨勢，逕流水中養份濃度以施肥後較高。 （三）旱季各處理土壤水分測定結果，以戀風草敷蓋區較高，無處理清耕對照區較低。雨季各處理土壤水分含量則以百喜草覆蓋區較高，仍以無處理清耕對照區較低。 （四）土壤化學性測定結果顯示：百喜草條帶及戀風草敷蓋處理區較佳，無處理清耕對照區較差，因水土及養份流失嚴重所致。 （五）根據土壤團粒平均粒徑、飽和導水率、假比重、分散率、孔隙率及土壤保水特性測定結果顯示：各處理以百喜草覆蓋較佳，而以無處理清耕對照區較差。 （六）本試驗結球白菜（夏陽品種）種植於高屏地區海34公尺之坡地，高溫多濕，產量不及高冷地。各處理以百喜草條帶及戀風草敷蓋處理區較高，無處理清耕對照區較低。 （七）根據各項綜合分析結果顯示：百喜草條帶及戀風草敷蓋處理對控制水土及養份流失，減少旱季土壤水分蒸發，改善土壤理化性，提高結球白菜產量之效果有較其他水土保持處理為佳之現象及趨勢，尤以旱季土壤水分含量，土壤有機質及有效態鉀含量與其他處理間差異達顯著水準。故在與本試驗區各項條件近似的20％坡地夏季蔬菜園採用本方法較佳，尚適於農機作業，符合省工經營原則，為一種簡易經濟有效的水土保持方法。 Field experiment was conducted on 20% slopeland with sandy loam soil facing southeastern direction at the Fengshan Tropical Horticultural Experiment Station. The purposes of this experiment were to compare the effects of various conservation methods on soil erosion control, soil moisture content, soil physico-chemical properties and vegetables production and to find out the most effective and economical method of soil conservation on slopeland for Summer. vegetable production. Four treatments including (A) reverse slope terrace;(B) strip covering and mulching with bahia grass; (C) strip covering and mulching with bahia grass and weeping love grass mowed for mulching; (D) cleancultivation were designed in this experiment, and the results were summarized as follows 1. The least amount of water run-off and soil loss were found in the plot of strip covering and mulching with bahia grass and weeping love grass mowed for mulching. The next was the plot of strip covering and mulching with bahia grass, and the worst was found in the plot of clean cultivation. 2. Amounts of nutrient loss in runoff water in each treatment were proportional to those of run-off and soil loss . The result also indicated that the higher concentration of nutrients in runoff water was found immediately after the fertilizer application. 3. The moisture contents of soil during the dry season indicated that the higher amount was found in the plot of mulching with weeping love grass, and the lower amount was found in the plot of clean cultivation. The moisture contents of soil during the wet season indicated that the higher amount was found in the plot of covering with bahia grass, and the lower amount was found in the plot of clean cultivation. 4. The soil chemical properties indicated that the best treatment was found in the plot of strip covering and mulching with bahia grass and weeping love grass mowed for mulching, and the worst one was found in the plot of clean cultivation. 5. Based on the record of mean size of soil aggregate, hydraulic conductivity, apparent specific gravity, dispersion ratio, and porosity, the best physical properties of the soil was found in the plot of strip covering with bahia grass, and the worse one was in the plot of clean cultivation. 6. Chinese cabbages (cv. Hsia yang) were planted on the slopeland (34m above sea level) of kaopin area, the yields were inferior to those grown in cool area. The highest Chinese cabbages yield was recorded on the plot of strip covering and mulching with bahia grass and weeping love grass mowed for mulching, and the lowest chinese cabbages yield was on the plot of clean cultivation. 7. Based on the aforementioned results, the treatment of strip covering and mulching with bahia grass and weeping love grass mowed for mulching which can afford to control the water, soil and nutrient loss effectively, reduce evaporation loss of soil moisture content improve soil physico-chemical properties and higher yields was better than any other treatment, and it is worth to be adopted as the ideal method of soil conservation on 20% slopeland for summer vegetable production