Low and highly unstable crop production and rapidly falling groundwater levels are the major challenges to be tackled in semi-arid rainfed areas. In south-eastern Rajasthan, high intensity and erratic rains associated with poor soil permeability creates excessive runoff and severe erosion hazards. In this region, through Conservation Bench Terrace (CBT), farm-rainwater harvesting can be done.In the CBT system, land is divided along the slope into 2:1 ratio. The lower 1/3rd area is levelled> for collecting runoff from the upstream 2/3rd area, which is left in its natural slope. Upper 2/3rd area is cultivated during kharif either with sorghum + pigeonpea intercropping or soybean. The lower 1/3rd levelled terraces are left fallow during monsoon and cultivated with mustard or gram during rabi. The cost of construction of CBT on 2% slope was about Rs 3,022/ha.
It was observed that through CBT,
- 21-29% of cropping season lost rainfall through surface runoff could be reduced to 13.4-15.8%.
- Reduced water erosion from 3.8-11 tonnes/ha/yr to about 2.2-3.2 tonnes/ha/yr
- 78.1% increase in grain and straw yields in terms of sorghum grain equivalent (SGE).
- Benefit: cost ratio of the system was 1.4:1.
- Benefits of soil and nutrients conservation
The CBT system can be successfully used in the semi-arid climate with mild slopes (2-5%) with sufficient soil depth for erosion control, moisture conservation and improvement of soil and crop productivity.
Central Soil and Water Conservation Research and
Training Institute, 218, Kaulagarh Road, Dehra Dun
(Uttarakhand) 248 195