坡地香蕉園草帶法試驗

Experiment of Vegetative Barrier on Slopeland Banana Plantation

1.本試驗之目的為採求草帶法在香蕉園水土保持之效益及最佳草種與適當行株組，並觀察陡坡地（26°）實施草帶法之可能性。2.本試驗之結果顯示三種草種中以戀風草最佳，天笠草次之，南非鴿草則不可取。就三草種之刈草敷蓋而論，以刈草敷蓋之方式為最佳，且可能為實施草帶法時之必要條件。八種處理中以戀風草草帶刈草敷蓋處理最具水土保持及增產效益，其增產效果較內斜式平臺增段表土不處理者為佳。各草帶處理在三年內即可漸進成為增段面向外作6-9度之增段。其在陡坡地（26°）之減小坡度效果亦佳。草帶法簡易，經濟而有效，且山邊溝可通行機械而草帶對機耕作業不若平臺增段妨礙之甚。故適於坡地香蕉園大面積之水土保持處理。

(1) According to the experiment on ”Observation on Terraces Formation by Vegetative Barriers” it was evident that vegetative barriers Could reduce a given slope and form terraces gradually. For the purpose of further studying the species of grass, mowing grass for mulching, merely mowing (no mulching), soil and Water loss, soil-building and yield etc., this experiment was carried out on 23% slopeland with clay loam at Chi-chi, Nantou Hsien from February 1965 to December 1968. Randomized complete block design with three replications and eight treatments was adopted as follows: (A) vegetative barrier of Guinea grass. Grass mowed for mulching. (B) vegetative barrier of Guinea grass. Grass mowed but not being used for mulching. (C) vegetative barrier of South African Pigeon grass. Grass mowed for mulching. (D) vegetative barrier of South African Pigeon grass. Grass mowed but not being used for mulching. (E) vegetative barrier of Weeping lovegrass. Grass mowed for mulching. (F) vegetative barrier of Weeping lovegrass. Grass mowed but not being used for mulching. (G) bench terrace with 18cm reverse slope and without retention of topsoil (H) clean-cultivated plot as check. (2) Results: Weeping lovegrass barrier with mulching treatment has the minimum run-off. Guinea grass barrier with mulching treatment is second. There is a maximum run-off from the clean-cultivated plot. Considering the effect of reducing run-off, the mowing grasses mulching treatment is more. effective than mowing grasses but not being used for mulching. So the grasses of the vegetative barriers should be mowed anti be used for mulching. When rainfall increases by one millimeter, the run-off of each treatment is shown below: The form abridges Soil loss in each treatment is proportional to the amount of run-off. Weeping lovegrass barrier with mulching has the minimum of about 4.8 tons per hectare in three years, It is less than that obtained from Guinea grass barrier with mulching. The maximum soil loss is obtained from the cleancultivated plot about 192 tons per hectare in 3 years. It is 38 times of the Weeping lovegrass and Guinea grass barriers with mulching treatments. During the dry season Weeping lovegrass barrier with mulching treatment has the maximum soil moisture content than other treatments. While reverse slope beech terrace and South African Pigeon grass barrier without mulching have the least. Weeping lovegrass barrier with mulching treatment has the highest fruit yields of 57 tons per hectare in 3 harvests including 2 ratoons. Guinea grass barrier with mulching yields about 54 tons/ha. Clean-cultivated and South African Pigeon grass barrier without mulching have the least. The degree of reduction of slope and soil-building are affected by the yield of grass and mulching treatment. However all vegetative barriers have considerable effect on the gradual formation bench terrace. The original slope of 13-degree was reduced to 6-9 degrees. In conclusion, this experiment indicates that the most appropriate treatment is vegetative barrier of Weeping lovegrass with mulching. It controls soil and water erosion, costs less expense and obtains the highest crop yield. The hillside ditch may be used as farm road for farm machineries. It has less limitation and interference than bench terrace in the field operation. Such method should be put into extension in the slopeland banana plantations.