熱帶地區生產夏季蔬菜之坡地水土保持方法研究

Studies on the Methods of Soil Conservation on Slopeland for Summer Vegetable Production in the Tropics

林昭雄(C. H. Lin) ； 鄭慶生(C. S. Cheng)

《中華農業研究》 34卷2期 (1985/06) Pp. 173-182

https://doi.org/10.29951/JARC.198506.0006

摘要

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。其目的在比較各種水土保持方法在坡地夏季蔬菜園對水土流失之控制效果，以及對土壤水分，土壤理化性和蔬菜生育之影響情形，以探究熱帶地區生產夏季蔬菜最佳的水土保持方法，進而確立熱帶地區坡地夏季蔬菜園合理的土壤管理方法，以供推廣之依據。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、戀風草敷蓋；四、無處理清耕對照區等四處理。茲將試驗結果摘要如下：
（一）水土流失測定結果，各處理逕流量及土壤流失量均以百喜草帶狀覆蓋及敷蓋區較少，其逕流量爲62cm/75平方公尺/yr，土壤流失量爲2.03kg/75平方公尺/yr內斜式平台增段次之，二者控制水土流失功能較大，而以無處理清耕對照區較多，其逕流量達213cm/75平方公尺/yr，土壤流失量達765.61kg/75平方公尺/yr。
（二）各處逕流水養份流失測定結果，以百喜草帶狀覆蓋及敷蓋區較低，無處理清耕對照區較高，並顯示剛施肥後逕流水中養份濃度較高，此時如遇強大降雨，養份流失必較嚴重。
（三）旱季土壤水分含量測定結果，均以敷蓋地區較高，無處理清耕對照區較低，敷蓋處理可減少土壤水分的蒸發。
（四）土壤化學性測定顯示，無處理清耕對照區因水土及養份流失較嚴重，與其他處理間之差異情形隨時間而變大。
（五）根據土壤平均粒徑，飽和導水率，假比重，分散率、孔隙率，滲透率及土壤水分特性測定結果顯示，各處理土壤物理性以百喜草帶狀覆蓋及敷蓋區較佳，而以無處理清耕對照區較差。
（六）本試驗甘藍種植於高屏地區海拔34公尺之坡地，高溫多濕，平均單球重不及高冷地，各處理區第二年產量，以內斜式平台增段區較高，百喜草帶狀覆蓋及敷蓋區次之，惟二者間差異未達顯著標準。
（七）根據本試驗初步綜合分析結果顯示，百喜草帶狀覆蓋及數蓋和內斜式平台增段二處理均能有效控制土壤流失，較對照區可增加產量均爲理想之水土保持方法，前者對改善土壤物理性功能較佳而且有利於機械作業，符合省工經營原則，故在與本試驗區各項條件近似的20%坡地夏季蔬菜園以採用百喜草帶狀覆蓋及敷蓋處理較佳。

並列摘要

Field experiment was conducted on 20% slopeland with sandy loam soil facing southeastern direction at the Fengshan Tropical Horticultural Experiment Station located at 22°33' North latitude. The purposes of this experiment were to compare the effects of various methods of soil conservation on the run-off of water and soil, soil moisture content, physical and chemical properties of soil as well as the growth of vegetables on slopelands for summer vegetable production. In order to ascertain and set up the most reasonable and applicable method of soil management on 20% slopelands for summer vegetable production, four treatments including (A) reverse slope terrace, (B) strip covering and mulching with bahia grass, (C) mulching with weeping love grass, and (D) clean cultivation were designed in this experiment, and the results of the first two years were summarized as follows:
1. The least amount of water runoff (62cm/75m^2/year) and the soil loss (2.03kg/75m^2/year) were found in the plot of strip covering and mulching with bahia grass among the four treatments. The next was the plot of reverse terrace, and the worst was found in the plot of clean cultivation. The water run off and soil loss reached 213cm/75m^2/year and 765.61kg/75m^2/year.
2. The least amount of nutrient loss in run-off water was found in the plot of strip covering and mulching with bahia grass, and the largest amount was found in the plot of clean cultivation. The result also indicated that the higher concentration of nutrients in run-off water was found immediately after the fertilizer application. Therefore, the heavy rainfall would cause the serious loss of nutrients.
3. The soil water contents during the dry season indicated that the higher amount was found in the plot of mulching, and the lower amount was found in the plot of clean cultivation. Therefore, the mulching treatment could reduce the evorporation of soil moisture
4. The soil chemical properties indicated that the more serious losses of nutrients as well as soil were found in the plot of clean cultivation. And the difference from other treatment could change to be larger with time.
5. Based on the record of mean size of soil aggregate, hydraulic conductivity, apparent specific gravity, dispersion ratio, porosity, and mechanical analysis, the best physical properties of the soil was found in the plot of strip covering and mulching with bahia grass, and the worse one was in the plot of clean cultivation.
6. Cabbages were planted on the slopeland (34m above sea level) of Kaopin area, the average yields of individual heads were inferior to those grown in cool area. Based on the results of the second year, the yield from the plot of reverse slope terrace was higher, and the next was from the plot of strip covering and mulching with bahia. However, these two trestments didn't show significant difference.
7. Based on the aforementioned results, the treatments of strip covering and mulching with bahia grass as well as reverse slope terrace can afford to control the soil loss effectively, and give higher yields than from the plot of clean cultivation. However, the former can improve better physical properties of soil and labor-saving practice than the latter. The strip covering and mulching with bahia grass are found to be the most ideal soil conservation measure and worthy be recommended as the ideal method of soil conservation on 20% slopelands for summer vegetable production in the tropics.