COULD GEOJUTE EFFECTIVE TO CONTROL EROSION AND RUN OFF ON AREAS WITH VARIOUS LAND SLOPE ?
Nurpilihan Bafdal
Agriculture Industrial Technolog Faculty - Universitas Padjadjaran, Sumedang 45363, West Java Indonesia
I. Abstract
Geojute is woven from a heavy, 100 percents jute yarn with a coarse, open mesh structure, and is the ideal erosion control material for land slope. Advantage of geojute are as
follows: 1 jute is a natural fiber that breaks down in one to two year and is not alien to the natural environment; ii decomposed of jute provides a nontoxic product which adds rich
organic nutrients to the soil; iii the coarse yarn of jute matting prevents excessive water flow washing a way soil and seed from the land slopes and iv geojute is flexible enough to
follow soil surface. Application of geojute on soils is another alternative engineering for reducing soil
erosion during the early stages of crop growth especially those crops which need a longer time for full canopy cover to develop. Combination of geojute with cover crops such as
grasses and legumes will have a significant impact in reducing the effect of raindrops on soil structure and therefore increase infiltration capacity, reduce run off velocity and absorbs
water. The purpose of the experiment was to study on the effect of geojute with cover crop
grasses and legumes to control erosion and run off on various sloping land. A field experiment was done at the Agricultural Experiment and Development Station in Arjasari
West Java, Indonesia. The experimental design employed was Split Plot Design with two factors respectively: combination of geojute with cover crops and degree of land slopes.
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Research results show that erosion and run off significantly increased with increase of slope gradient except when the soil was covered by geojute combined with grass in
significant soil loss occurred. Soil covered with geojute combined with grass gave the least run off and was significantly different as compared with other treatments.
Keywords: geojute, soil cover, erosion, run off.
II. Introduction
Poor land management engineering, which are not based on soil conservation principles accelerate soil destruction. Poor control causes diminishing soil productivity and creates in
due time critical land. Proper conservation practice usually combines farming practices with proper land use, however, under humid tropical conditions, these practice do not always
adequately control water concentrations caused by heavy to very heavy rain storms. In the traditional farming system on upland soils in developing countries such as
Indonesia, farmers in general pay little attention in using cover crops to prevent soil from erosion and destruction. In humid regions, an equilibrium is normally established between the
process of soil formation and the removal of soil by erosion, except on very steep slopes. The importance of crop cover, for controlled erosion and run off is well known. Erosion
control by vegetation method only especially on steep land slopes is not effective. Judicious soil and crop management practices which help produce an early ground cover are certainly
more effective in controlling run off and erosion than those practices which need a longer time to produce full canopy cover to protect the soil Lal, 2000 . Growth habit of a given
crop cover has to some extent influence on controlling soil erosion and run off. However, soil management plays a more determinant Hudson, 2000.
A soil conservations must consider the ultimate purpose of restoring land, his detailed decisions will be determined by the physical and environmental characteristics of the area. He
has to select, within his constraints set, those policies or decision rules which, when implemented, assist him in moving forward his ultimate goals.
Application of geojute on soils is another alternative engineering for reducing soil erosion during the early stages of crop growth especially those the crops which need a longer
time for full canopy cover to develop. The run off and erosion loss which occur under these crops are proportional to the time required for full canopy cover to developed.
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Combination of geojute with cover crops such as grasses and legumes will have a significant impact in reducing the effect of raindrops on erosion and run off. In addition,
geojute improves soil structure and therefore increases infiltration capacity, reduces run off velocity and absorbs water.
Geojute is woven from a heavy, 100 percents jute yarn with a coarse, open mesh structure, and is the ideal land surface needs stabilization and protection from erosion prior to
the establishment of vegetation cover. Advantages of geojute are as follows : i
Jute is a natural fiber that breaks downs in one to two years and is not alien to the natural environment.
ii Decomposed jute provides a nontoxic product which add rich organic nutrients to the
soil. iii Geojute is flexible enough to follow surface contours and is ideal for particularly steep
slopes. Trials conducted by Sembenelli 1986 in Italian alps an ultimate of 2000 meters and on
slopes of 45; showed that average soil erosion and run off was 50 percent less on the slope covered by jute when compared to soil without cover by geojute. The soil loss from soil
surface of untreated slope averaged 6 mm in depth; while on the geojute covered slope was only 1.5 mm in depth ; which was a reduction of 65 percent. The run off on slope covered by
geojute was only 10 percent of the volume of run off. The success of geojute in this particular trial was due to three main factors :
a. The ability to absorb water thereby reducing run off; b. The ability to improve soil structure which inhibited erosion ;
c. The ability to protect the soil against raindrops.
Thompson 1995 and Harris et al 1996 stated that geojute is biodegradable and rots about two years. Being a natural fiber, geojute adds over 2 tons per acre of rich organic
matter of the soil, the composing fiber assists in the retention of moisture and the improvement of the soil permeability Haris et al,
1996. Since slope protection in the long term is provided by the grass, jute affords acceptable protection in the short term to the seed
of the grass in not washed off the slope before it germinates and takes root Thompson, 1995. Figure 1 below show using geojute as “soil saver” in the plot experiment; was done at
the Agricultural Experiment and Development Station in Arjasari West Java Indonesia.
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Figure 1. Using geojute as “soil saver“ in the plot experiment
The presence of decomposed geojute on the surface on the soil creates an increased roughness, which reduces run off velocity and also traps soil particles. Therefore, once it is
installed there is no need to ever remove it. By retaining a surface cover of coarse particles, jute reduced the erodibility coefficient of
the soil and so limits the scope of progressive rain splash detachment. The protection afforded by covering the surface is an obvious mechanism by which the yarns of the jute absorb most
of the kinetic energy of raindrops directly on the jute. Soil or land management practice are based on two broad principles Lal, 2000 :
i To maintain a high soil infiltration rate at sufficiently high levels to reduce run off; and ii To help safe disposal of run off from the field, should rainfall exceed the infiltration
capacity of the soil. Culture practice which help maintain a high soil infiltration rate are essentially based on
farming technique which maintain mulching and no tillage or minimum tillage, and no tillage or minimum tillage and use of cover crops.
The unique construction of geojute allows plenty of room for plants to growth and light to enter between the strands. Any variety of grasses or legumes as a ground cover can be
selected to fit site and climatic combination of geojute with cover crops such as grasses or legume will cover the land surface and prevent run off and soil loss by reducing the run off
velocity, because more time is required or the water to penetrate into the soil. Therefore monitoring soil infiltration rate is important in predictions of run off and soil loss Lawes,
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1999. The higher the percentage of ground coverage the lesser the effect of the impact of rain drops on erosion and run off.
In addition the extensive root system of grass improves soil porosity and consequently increases infiltration capacity, it also binds soil particles into stable aggregate which can stand
the adverse effect of rain. Grass strips also play as a mud sieve which prevent clogging up of soil pores.
The run off and soil erosion losses which occur under any crops species are proportional to the time required for full canopy cover to developed. Branching habit of crop species is
also a factor in the development of the canopy. A soil depleting crop grown with proper soil conserving engineering such as geojute
gives less run off and soil loss than a soil conserving crop grown with erosion promoting practice. The soil management practices, therefore, are more critical to run off and erosion
control than selection of suitable crops. The purpose of this experiment was to study on sloping land the effect of combination of
geojute with grasses and legumes as a ground cover on soil erosion and run off. The results are expected to contribute to soil and water conservation engineering that will maintain soil
productivity.
III. Material and Methods
