ABSTRACT
The study involving Yard
Long bean was conducted at the Soil Conservation and Watershed Management
Centre (SCWMC), Soil Resource Development Institute (SRDI), Bandarban during May
2012 to December 2012 to investigate the effect of Effect of different hedge species on controlling soil erosion, runoff,
nutrient mining and yield and yield attributes at steep slope in CHT. The
treatments were: T1: Indigofera
hedge, T2: Napier hedge, T3: Pineapple hedge and T4:
Control (without hedge). Hedges have created positive impact on reducing soil
loss in Yard Long bean growing plots. Fruit length, fruit diameter, fruit
weight, no. of fruit per plant, no. of seeds per fruit and yield of Yard Long
bean responded to the application of different hedges.
INTRODUCTION
The conservation of soil and
water is essential for sustainable production, environment preservation and
balanced ecosystem (Sarma et al. 2000). Loss of soil by water erosion on
slopping lands adversely affects the physical, chemical and biological
properties of soils, leading to low crop productivity (Larson et al.1985
and Sur et al.1994). Land use change associates erosion is mostly
responsible for land degradation and desertification in different part of Asia
and Africa, bringing about large reduction in
vegetation growth, siltation of water courses, filling of valleys and
reservoirs and the formation of deltas along the coastal areas. Erosion is
accompanied by deposition of alluvial materials by flooding and filling of
valleys, waterways or extending coastal plains and deltas towards the sea. Contour
hedgerows are also effective in controlling run off and soil erosion and
improve soil physical properties. Control plots have higher run off and soil
loss than those plots with hedgerow (Khisa et
al. 1999). Uddin and Firoz (2001) recommended hedgerow for cultivation on
sloppy land. They described that hill slope may be divided into a series of
alley separated by hedgerow on contour lines, because hedgerow plants are
effective in controlling soil erosion and reducing run off. A number of
research works have been conducted in the tropics regarding soil fertility
improvement under agroforestry practices. Agboola et al. (1982) as cited by Attah-Krah and Sumberg (1988) reported
that the soil chemical properties like pH, OM,
N, available P and CEC improved with the use of Gliricidia sepium as hedgerow. Attah-Krah et al., (1986) as cited by Nair (1993) reported that organic matter
content and nutrient levels of soil were higher under alley cropping as
compared to soil without trees.
Trees and shrubs have several
functions to control erosion like (i) increase soil cover, by liter and pruning
(ii) provide partly permeable hedgerow barriers (iii) lead to the progressive
development of terraces, through soil accumulation upslope of hedgerows (iii)
increase soil resistance to erosion, by maintenance of organic matter (iv)
stabilize earth structures by root systems and (v) make productive use of the
land occupied by the conservation works
(Young 1989 a). Alley cropping or hedgerow cultivation is very helpful
in controlling of soil erosion in the hilly area. Hill Tract Development Board
of Bangladesh identified five nitrogen fixing tree species like Leucaena leucocephala, Gliricidia sepium,
Indigofera tysmani, Fleminigia spp, and Desmodium
rensonii etc. and two grass species Vetiviera
zizanoides and Thysanolaena maxima
for controlling runoff and erosion in the hilly region of Bangladesh (Khisa et al., 2002). Singh et al. (1990) found that runoff and soil
loss were substantially reduced when small watersheds with agriculture were
replaced either by trees and grasses (silvipasture) or with mechanical
measures. In a study, Wiersum (1984) found that different agroforestry systems
cause lowest soil erosion.
Facing the location specific,
environmental friendly agricultural developme
nt challenges in CHT, Soil
Conservation and Watershed Management Center (SCWMC), Bandarban has stepped up
its efforts to generate scientific information on the major land use practices
in the region, This study is the first attempt to investigate and quantify the
effect of different hedge species on soil loss and run-off and its economic
performance on crop cultivation. Therefore, the present study undertaken to
find out the feasible hedge species for controlling soil erosion and for crop
cultivation in the CHTs.
OBJECTIVES
a. To
compare soil loss, runoff and nutrient mining under different hedge row
cultivation system.
- To evaluate the economical aspects of Yard Long bean cultivation under different hedge
species.
MATERIALS AND METHODS
The experiment was carried out under non
replicated condition. Four experimental plots of 100 sqm (5 m x 20 m) on
steeply undulating (36%) slope was selected in the SCWMC, Bandarban. Three
different species were used as hedge species like; Indigofera, Pineapple and Napier. Hedge species were planted in
2005 following contour lines maintaining 5 m alley distance but the data of the
experimentation were recorded during 2012-13. Seeds of yard long bean were
dibbled in pits. Fertilizer & manure were used as per STV. Pits were dug at
a distance of .45m from plot boundary maintaining column & row having equal
distance (90cm). There were 23 rows and 6 columns. After germination 2
seedlings were allowed in each pit for yield. So there were 276 (23x6x2) plants
in each plot. Measurement of soil loss and run-off was carried out by
established and locally fabricated multi-slot divisors. Natural condition of
the slopes was not disturbed or no any soil work was done to make artificial
slope. Cultural operations were done as usual in all the plots. Soil loss and
run-off from each 100sqm (5m x 20m) experimental plots were measured after each
shower throughout the rainy season. Daily and eventually monthly soil loss and
run-off were estimated from each treatment by processing aliquot of sample
every day. Every morning (if rains previous day) amount of run-off water is
measured in the multi-slot and aliquot of about 2 L is sampled from each tank.
Suspended sediment in the sampled aliquot is measured by simple filtering and
oven drying. Corresponding rainfall is recorded from the automatic and ordinary
rain gauge of SCWMC. Climatic data like rainfall, temperature, humidity,
evaporation etc. were recorded daily. Yard Long bean was selected as a test
crop. Different agronomic practices were done when it was necessary.
RESULTS AND FINDINGS
Soil loss under different hedge
species cultivation in cultivating okra in 2012 session is presented in table
1. Soil loss of okra at the alley of different hedge species throughout the
rainy season were calculated (Table 1). It was recorded that highest soil loss
was recorded in control plot (40.71 t/ha) where no hedge species were used,
followed by indigofera hedge species used plot (16.74 t/ha), napier
hedge species used plot (12.06 t/ha) and pineapple hedge species used plot
(9.28 t/ha).
Table 1: Soil loss
under the cultivation of different hedge species in 2012
Particulars
|
Jan
|
Feb
|
March
|
April
|
May
|
June
|
July
|
Aug
|
Sep
|
Oct
|
Nov
|
De
|
Total
|
Indigofera
|
-
|
-
|
-
|
-
|
-
|
2.38
|
5.19
|
4.72
|
3.20
|
1.25
|
-
|
-
|
16.74
|
Napier
|
-
|
-
|
-
|
-
|
-
|
1.62
|
3.95
|
3.54
|
2.16
|
0.79
|
-
|
-
|
12.06
|
Pineapple
|
-
|
-
|
-
|
-
|
-
|
1.60
|
2.88
|
2.61
|
1.50
|
0.69
|
-
|
-
|
9.28
|
Control
|
-
|
-
|
-
|
-
|
-
|
4.44
|
13.36
|
11.78
|
7.28
|
3.85
|
-
|
-
|
40.71
|
Runoff of Yard Long bean at the
alley of different hedge species throughout the rainy season were calculated (Table
2). It was recorded that highest runoff was recorded in control plot where no
hedge species were used, followed by indigofera
hedge species used plot, napier hedge species used plot and pineapple
hedge species used plot.
Table 2: Run off
under the cultivation of different hedge species in 2012
Particulars
|
Month wise runoff (mm and %) 2012
|
|||||||||||
Jan
|
Feb
|
March
|
April
|
May
|
June
|
July
|
Aug
|
Sep
|
Oct
|
Nov
|
De
|
|
Indigofera
|
-
|
-
|
-
|
-
|
-
|
25
|
46
|
34
|
11
|
6
|
-
|
-
|
Napier
|
-
|
-
|
-
|
-
|
-
|
22
|
33
|
15
|
8
|
6
|
-
|
-
|
Pineapple
|
-
|
-
|
-
|
-
|
-
|
18
|
27
|
14
|
6
|
4
|
-
|
-
|
Control
|
-
|
-
|
-
|
-
|
-
|
40
|
58
|
37
|
16
|
11
|
-
|
-
|
Crop yield under the cultivation of different hedge species
Hedge species
pineapple performed the best in producing higher pod length (55.50 cm) , pod diameter (2.05 cm), pod weight (18.19 g),
number of pod per plant (19), number of seeds per pod (23.00) and yield
(9.54 t/ha) over other hedge applied plots and control plot (Table 3).
Table 3: Yield and
yield attributes of Yard Long Bean under the cultivation of different hedge
species in 2012-13
Particulars
|
Pod length (cm)
|
Pod dia(cm)
|
Pod wt. (gm)
|
No. of Pod/plant
|
N. of seed/ Pod
|
Yield (t/hac)
|
Pine apple
|
55.50
|
2.05
|
18.19
|
19
|
23.0
|
9.54
|
Napier
|
51.29
|
1.97
|
17.82
|
17
|
22.00
|
8.36
|
Indigofera
|
48.36
|
1.88
|
15.21
|
16
|
20.00
|
6.71
|
Control
|
44.50
|
1.63
|
13.59
|
14
|
16.00
|
5.25
|
CONCLUSION
- Use of different hedge has created positive effect on the morphological and reproductive characteristics as well as at the yield of Yard Long bean.
- Between three hedge species pineapple hedge reduced relatively higher soil loss due to its soil binding capacity of roots.
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