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.
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.
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.
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.
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
3.1 Experimental Method
A filed experiment was done at The Agricultural Experiment and Development Station in Arjasari West Java, Indonesia. Each field plot was 7 x 1m2, laid out on various land slopes. Eroded soil and run off were collected in the first week after planted grasses and legumes.
3.2 Time Schedule of Experiment
The time schedule of the experiment was as follows : (i) Plotting and installing geojute
(ii) Field experiment was conducted in rainy seasons
(iii) Analysis of chemical and physical properties of soil was done in the laboratories after the experiment was finished.
The Experimental design employed was Split Plot Design with two factors respectively: combinations of geojute with cover crops (V) and degree of land slopes (S). The levels of treatment were as follows :
v1 : combinations of geojute with bahia grass (Paspalum notatum) v2 : combination of geojute with legumes( Centrosema sp )
v3 : bahia grasses (Paspalum notatum) without geojute v4 : legumes ( Centrosema sp ) without geojute
The factor degree of land slope(s) consisted of 4 levels respectively s1 : 20 percent land slope
s2 : 30 percent land slope s3 : 40 percent land slope s4 : 50 percent land slope
16 treatments in 2 replications were analyzed, number of experimental plots were 32 plots. Plot with geojute only i.e. without crops on each degree of land slope functioned as a control.
IV. Result and Discussion
IV.1.
Soil Loss (kg/plot)The mean cumulative values of soil loss analysis of combination geojute with cover crops for different slopes identified that soil loss from the soil without geojute was large than from a plot covered with geojute (Table 1).
Soil loss from cropland significantly increased with an increased of slope gradient except when the soil was covered by geojute combined with bahia grass in significant soil loss occurred. From this fact we can conclude that slope loss when geojute is used in combination with grass. It appeared that either bahia grass or legumes alone, could not prevent soil loss when slope gradient increased, although bahia grass was much more better as a soil conservator than legumes.
Table 1. Soil loss from plot protected and unprotected with geojute (kg/plot)
v1
The mean values (s) of soil loss not followed by small letter are significantly different at P = 0.05 for slopes gradient (vertical comparison)
The mean value (s) of soil loss not followed by the same capital letters are significantly different at the P = 0.05 for soil cover treatment (horizontal comparison)
There were no significant differences of soil loss between soil covered with geojute in combination bahia grass (v1) and with legumes (v2) on slopes gradient 20 percent and 30 percent significantly affected. However, this was not the case on steeper slopes 40 percent and 50 percent, geojute when combined with bahia grass could totally prevent soil loss. Much soil was loss from the untreated soil with geojute as compared with geojute treated soil.
IV.2.
Run Off (m3/plot)Run off is portion of the precipitation that makes its way toward stream channels, lakes or ocean as surface or subsurface flow. Type and condition of cover crops, degree of slope, kind and condition of soil, and climate all markedly affect soil erosion and run off. Bennet (1999) noted that the importance of land slope in relation to the soil erosion and run off from cultivated land is revealed in the measurement of rate of erosion and run off under compactable conditions of soils, cover crops and rain fall. Slope gradient is important because the velocity of water movement and its ability to detach and carry soil particles increases exponentially with increases in slope gradient. Under cultivation, run off are usually greater from the steeper slopes.
Table 2. Run off from plot protected and unprotected soil with geojute (m3/plot)
The mean values (s) of soil loss not followed by small letter are significantly different at P = 0.05 for slopes gradient (vertical comparison)
The mean value (s) of soil loss not followed by the same capital letters are significantly different at the P = 0.05 for soil cover treatment (horizontal comparison)
From Table 2 show that the mean cumulative values of run off occurred differently on treated soil v1 are : 0.23: 0.29: 0.35 and 0.46 m3/plot for slopes gradient 20 : 30 : 40 and 50 percent respectively. But mean cumulative values of run off for treated soil v2 (combination of geojute with legumes) at slope gradient 30 and 40 percent were not significantly different. Result presented in Table 2 show that mean cumulative run off an 50 percent slope was only two times greater than from a 20 percent slope for all treatment (v1,v2,v3,v4). Soil covered with geojute combined with bahia grass gave the least run off and was significantly different as compared with other treatments (v2, v3 and v4).
V. Conclusions
1. Treatment of soil surface layer with geojute as ground cover either combined with bahia grass or legumes reduces soil erosion and run off as compared to soil cover treatment with bahia grass or legumes only. The pointed effect of geojute was more apparent on steeper slopes :
a. Ability to absorb water, effected reducing of run off velocity and increasing the time for the water to penetrate into the soil
b. Protected soil by covering the surface layer by which the yarn of jute absorb of kinetic energy of raindrops.
2. For soil The Agricultural Experiment and Development Station in Arjasari ( West java, Indonesia), combination of geojute and bahia grass could reduce soil loss 6 (six) to 35 times as compared to soil covered with legumes only 2 (two) to 3 (three) as compared to bahia grass as ground cover. The run off was only 2 times greater, a plot with combination of geojute with bahia grass gave result less than that from combination of geojute with legumes for all treatment of percent slopes.
More experiments have to be conducted with a wide range of soil and crop management practice to test and refine to result reported here, especially time required to composed of jute to add organic matter into the soil.
3. Geojute could effected to control erosion and run off on areas with various slope.
VI. Reference
Bennet, H.H, 1999, Soil Conservation. Mc Graw Hill Book Company Inc, New York – London.
Harris, G. et al., 1996, Jute Soil Antiwagh. Control Erosion Along Interstate 65, Auburn. Erosion Control Co of Auburn Alabama.
Hudson, N., 2000, Soil Conservation. Cornel University Press Ithaca, New York.
Lawes, D.A., 1999, Rainfall Conservation and the Yields of Sorgum, and Groundnuts in Northern Nigeria Sormaru Res Bul. No. 70
