EFFECT OF SLOPE GRADIENT AND HEDGE SPECIES ON SOIL LOSS AND CROP YIELD IN CHITTAGONG HILL TRACTS

ABSTRACT

The study involving maize 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 and slope gradient on controlling soil erosion, runoff, nutrient mining and yield and yield attributes at moderate slope in CHT. The treatments were: T₁: Indigofera hedge, T₂: Pineapple hedge and T₃: Control (without hedge). Slope gradients were gentle (12%) and moderate (26%). Hedges as well as slope gradient has created impact on soil loss in Bitter Gourd growing plots.  Plant height, fruit length, fruit diameter, seeds per fruit, 100 seed weight and yield of Bitter Gourd responded to the application of different hedges and slope gradient.

OBJECTIVES

a    To compare soil loss, runoff and nutrient mining in cultivating Bitter Gourd under     

       different hedge species and slope gradient.

      b. To evaluate the economical aspects of cultivation under different hedge species.

MATERIALS AND METHODS

 The experiment Indigofera and Pineapple. Hedge species were planted in 2009 following contour lines maintaining 5 m alley distance but the data of the experimentation were recorded during 2012. 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. Pits were dug 1.80 m c/c  in rows maintaining contour. Total number of pits in each plot were 24. Fertilizers were applied as per recommendation of soil test value. 3 to 4 nos of seed were sown in each pit. After germination, two seedling were allowed for yield.  Cultural operation 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 Litre 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. Bitter Gourd was selected as a test crop. Different agronomic practices were done when it was necessary.

Experiment  was carried out under non replicated condition. Two different slopes were selected to carry out the experiment. Three experimental plots of 100 sqm. (5 m x 20 m) on gently (12%) and moderately undulating (26%) slope were selected in the SCWMC, Bandarban. Two different species were used as hedge species like;

Results and Findings

Gentle slope

Soil loss under different hedge species in gentle slope at Bitter Gourd growing plot during 2012-13sessions is presented in table 1. Soil loss under Bitter Gourd at the alley of different hedge species throughout the rainy season was calculated. It was recorded that highest soil loss was recorded in control plot (21.45 t/ha) where no hedge species were used, followed by indigofera hedge species used plot (13.16 t/ha) and pineapple hedge species used plot (8.53 t/ha).

Table 1: Soil loss under the cultivation of different hedge species in 2012

Particulars						June	July	Aug	Sep	Oct	Nov	De	Total
Indigofera						2.63	3.92	3.22	2.93	0.46	-	-	13.16
Pineapple						0.96	2.65	2.54	1.98	0.40	-	-	8.53
Control						3.29	6.02	5.95	5.13	1.06	-	-	21.45

 Runoff under maize 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 and pineapple hedge species used plot.

Table 2: Run off under the cultivation of different hedge species in 2012

Particulars	Month wise runoff  (%) 2012
	Jan	Feb	March	April	May	June	July	Aug	Sep	Oct	Nov	De
Indigofera	-	-	-	-	-	16	39	31	27	20	-	-
Pineapple	-	-	-	-	-	13	32	28	25	16	-	-
Control	-	-	-	-	-	31	47	40	34	21	-	-

 Moderate slope

 Soil loss under different hedge species in moderate slope at Bitter Gourd growing plot during 2012-13 sessions is presented in table 3. Soil loss under Bitter Gourd at the alley of different hedge species throughout the rainy season was calculated. It was recorded that highest soil loss was recorded in control plot (23.35 t/ha) where no hedge species were used, followed by indigofera hedge species used plot (14.22 t/ha) and pineapple hedge species used plot (9.14 t/ha).

Table 3: Soil loss under the cultivation of different hedge species in 2012

Particulars						June	July	Aug	Sep	Oct	Nov	De	Total
Indigofera						1.72	5.34	4.90	1.69	0.57	-	-	14.22
Pineapple						1.25	3.03	2.85	1.32	0.69	-	-	9.14
Control						3.23	8.75	7.49	2.91	0.97	-	-	23.35

              Runoff of okra at the alley of different hedge species throughout the rainy season were calculated (Table 4). It was recorded that highest runoff was recorded in control plot where no hedge species were used, followed by indigofera hedge species used plot and pineapple hedge species used plot.

Table 4: Run off under the cultivation of different hedge species in 2012

Particulars	Month wise runoff  (%) 2012
	Jan	Feb	March	April	May	June	July	Aug	Sep	Oct	Nov	De
Indigofera	-	-	-	-	-	8	15	13	11	3	-	-
Pineapple	-	-	-	-	-	5	10	7	6	2	-	-
Control	-	-	-	-	-	20	33	28	19	10	-	-

Effect of Slope Gradient and hedge species on the Performance of Bitter Gourd at Chittagong Hill Tracts

Fruit per pit, Fruit length, Fruit diameter, and yield Bitter Gourd was recorded (Table 5). It was found that all the yield and yield attributing character was influenced by slope gradient and hedge species. The highest number of Fruit per pit, Fruit length, and Fruit diameter, and yield was recorded in gentle slope as well as under pine apple hedge species and it was higher than other slope and hedge species. Difference of yield and yield attributing characters of Bitter Gourd was due to slope gradient and hedge species. The higher the slope gradient the higher the soil loss and the thickness of top soil may decrease as a result top soil contain lesser plant nutrients for that reason the performance of crop may deteriorated. Bitter Gourd

Table 5. Yield and yield attributing characters of Bitter Gourd as influenced by different 

                 slope gradient and hedge species

Treatments	Fruit per pit	Fruit length,  (cm)	Fruit diameter (cm)	Av.Weight/ Fruit (gm)	Yield /Pit (Kg)	Yield (t/ha)
Indigofera (G)	36.49	19.07	14.16	119.89	4.375	10.50
Pineapple (G)	38.89	20.12	14.30	131.13	5.100	12.24
Control (G)	30.15	17.26	13.81	112.20	3.383	8.12
Indigofera (M)	30.98	17.87	12.35	116.09	3.596	8.63
Pineapple (M)	35.07	19.05	12.64	125.45	4.40	10.55
Control (M)	29.30	15.81	12.06	105.32	3.086	7.41

CONCLUSION

Ø  Use of different hedge has created positive effect on the morphological and reproductive characteristics as well as at the yield of Bitter Gourd.

Ø  Between two hedges pineapple hedge reduced relatively higher soil loss due to its soil binding capacity of roots both in the gentle and moderate slope.

Ø   Between two hedges pineapple hedge reduced relatively higher runoff both in the gentle and moderate slope.