Water Harvesting and Conservation Techniques for range improvement and crop production in dry areas of Pakistan
Dr. Muhammad Tahir and Dr. Aziz-Ur-Rehman*
Department of Agronomy, University of Agriculture, Faisalabad, 38040, Pakistan.
*Corresponding Author: [email protected]
Pakistan is mostly a dry land country having 75% area in semiarid and arid zone where commercial forestry and agriculture is not possible without water. The world’s biggest canal irrigation system for agriculture production is present in this area of the country covering almost an area of about 14 million hectares. In those areas where ground water is good for irrigation, ground water irrigation system is common in addition to canal irrigation system. The inhabitants of the dry areas are poor, due to lack of irrigation sources; they depend upon rain fed farming.
In dry zones, rain fed agriculture is in subtropical area with broad leaved evergreen forest having annually mean rainfall 800 mm. Rain fed agriculture in tropical zones with forest area is practiced under following four conditions,
- Areas having annually mean rainfall more than 250 mm with sandy deserts.
- Areas along riverine having annual inundation.
- Rode Kohi areas or water spreading.
- Khushaba or water harvesting in sloping lands.
Due to reduction in floods in Indus River, the flood recession agriculture in riverine areas is now limited, because of construction and improvements of artificial reservoirs, development of canals and barrages for irrigation.
Farming is practiced in sandy areas after receiving seasonal rainfall, but yield and crop production in such areas is very low. Rode kohi is the best method for agriculture in such areas, but this system depends upon hill torrents, but these are not regular and crop production through water spreading is not an annual feature. Khushaba (traditional water harvesting) depend on rainfall, so crop production with this system also depends on rainfall water having good runoff. In northwest areas of Balochistan of dry temperate zone, northwestern hilly areas of Northern areas and KPK, very limited agricultural farming is practiced through water spreading (Sailaba) and conventional water harvesting system. In some areas, the inhabitants are very poor and their livelihood is only on the livestock production, living below the poverty line. The farming is considered as subsistence farming and agricultural crop productivity is not optimum in the rain-fed dry zone. Natural rangelands and forests are good source of forage for livestock, fuel wood is obtained for cooking, timber for shelters and other types of non-timber is used for health needs and nutritional purposes.
In dry zone areas, mostly natural forests are in degraded conditions, if once they lost then it is very difficult to regenerate them due to lack of water and poor climate conditions. It is also not easy to regenerate by reforestation system as it is not feasible and economically good due to tanker and hand watering. Although these limitations are present, but reforestation of dry zone areas is an important issue as it is the need to conserve the area and provide sources to local inhabitants for their livelihood. According to research and development programs and activities in these areas, water harvesting techniques with combination of special species can make the reforestation program successful.
For the development of natural resources in such areas, water play an important role. There is minimum number of rainfalls, but if the rainwater is collected from the large areas, then it will be sufficient for the production and development of natural resources. These plantations in rainfed areas can be survival and economical as well as production will also be high. Water harvesting is a beneficial technology for the local inhabitant’s livelihood improvement and it will also useful for the development of dryland areas.
1. Drylands of Pakistan:
Pakistan has variety of ecological zones because of different orientation and topographical features ranging from tropical to alpine pastures. About more than 75% area of the country is covered by the dry tropical, subtropical and dry temperate zone among these ecological zones. In the northwestern Balochistan, Northern areas and northwestern highlands of KPK, dry temperate zone is present. The foothills of Himalayas are covered by subtropical zone and western parts of country are covered by the Suleman Range and Salt Range.
The whole plain areas of Punjab, Sindh, KPK and Balochistan merging with subtropical zone are covered by the dry tropical zone. The annual rainfall have great variations from year to year mostly ranges from 125 to 350 mm. In June mean maximum temperature remains about 41°C with extreme maximum temperature to 51.5°C and it is considered as hottest month. In northern parts mean minimum temperature drops to 5.5oC. Between the bank of main channel of Indus River and its tributaries riverine belt is located. It has same climatic conditions except those areas receive inundation from the river and is located in the tropical thorn forest zone.
Subtropical broad leave evergreen forest zone is spread over the foothills and lower slopes of the Himalayas, the Salt Range and Suleman Ranges. In fact, it occurs at suitable elevations merging upward subtropical pine and downward with the tropical thorn forest and temperate forests throughout the country. The annual rainfall ranges from 250 to 750 mm of this area. Beyond the effective reach of monsoon, throughout the inner mountain ranges the dry temperate zone is spread, notable in the Indus inner reaches and its tributaries along with the parts of Chitral and whole of Gilgit, Kaghan valleys and Neelum; in the northwest Balochistan also the higher parts of Suleman Range. The winters are cold and long. The precipitation receives annually during winter and spring and average precipitation ranges from 200 to 500 mm.
2. Water Harvesting & Conservation for Crop Production:
Annual rainfall in the dry zone is low, but if the rainwater during rainfall season is properly conserved, it can be feasible for the improvement of natural resources which will improve the inhabitant’s livelihood. In dry zone water harvesting technology can increase the crop production in those areas where there is no crop production or the yields are very low.
2.1. Methods of Water Harvesting and Conservation in Hilly Areas:
To develop ponds in the hilly areas, dikes can be constructed at suitable places in the streams. Through the diversion of stream water or storing at safe and suitable places diversion ponds can also be developed. Water of the pond can be used for domestic and drinking purposes. This water is also suitable to use for irrigation for crops production and livestock. For crop production in plan and hilly areas various suitable water harvesting techniques can be used. For crop production in hilly areas following are the suitable water harvesting techniques;
i) Foothill Basins:
At the foothills the terraces are developed with strong dikes around the fields except the upper side to trap and conserve runoff from the hills for crop production.
ii) Conservation Benches (Desert Strips):
Conservation benches are the terraces developed on the sloping land by leaving a section of slope untreated for runoff production. The ratio of the water conservation and crop production depends on the rainfall of the area.
iii) V-shaped Micro-catchments and Individual Basins:
These are small size water harvesting structures developed for the establishment of fruit trees in gullied or broken areas.
2.2. Methods of Water Harvesting & Conservation for Plain areas:
Combining ponds development technique with water harvesting system in the plain areas is good practice for fodder trees production. The extra runoff produced from roaded catchments established for fodder tree can be used for pond development. The overflow of water is collected from the roaded catchments in the cross ditches and then into main drain which takes the collected runoff into the pond excavated in soil. Water has to be pumped for irrigation as the pond is below the soil surface. To provide clear and filtered water for drinking purpose to local inhabitants a small filtration plant can be set up. The water in the pond is conserved through evaporation control measures and low cost seepage. Pond water should be used carefully as it is valuable commodity; to avoid losses it should be used with sprinkler irrigation or furrow irrigation system for vegetable production. Establishment of fruit orchards through drip irrigation or any other low cost irrigation system is also economically better. In dry areas for the small farmers earn income and improve their livelihood fruit and vegetable production is the best option. Now water harvesting is the cheaper process and within the reach of small farmers through mechanization. Description of water spreading and water harvesting system for crops production is given below:
i) Roaded Catchments for crop production:
The slopes of the catchments are kept longer to produce more runoff for production of the crops. Crop production area is kept half of the total water production area.
ii) Roaded Catchments for fruit Trees:
The length of the slopes is 5 m while width of the drain is 1.5 m to develop troughs for establishing fruit trees. The troughs are developed at 8 m spacing. The spacing of the orchards is 11 × 8 m.
iii) Individual Basins:
Individual basins are bounded by the dikes on all the sides and slope is given to the center where a pit is excavated for fruit trees. The length of dikes of the square basin is 8 m. The technique is relatively expensive because of partial manual work.
iv) Water spreading for crop Production:
The water spreading is diversion of flood water of ephemeral streams, and taken to comparatively plain area for crop production through dikes. It is an indigenous technology and is being used in many areas of Pakistan for crop production. It needs improvement for increasing the crop yields.
2.3. Techniques for Water harvesting & Conservation for Range Improvement in Hilly Areas:
Rangelands can be improved through water harvesting techniques, both in hilly as well as plain areas. In the hilly areas the following water harvesting techniques are suitable for sowing of high yield grass species;
i) Conservation Benches for grass sowing:
The conservation benches for crop production can also be used for sowing of grasses. These are the terraces developed on the sloping land by leaving a section of slope untreated for runoff production. The ratio of the water conservation and crop production depends on the rainfall of the area.
ii) Contour Trenches for grass sowing:
The contour trenches having 3 m length and 0.3 m width and depth are used for sowing of good quality grass on small scale in the hilly areas.
iii) Hillside Ditches for Silvo-pastoral system:
Hillside ditches are continuous ditches excavated with tractor driven ditcher for planting of fodder trees and sowing of grass to develop silvo-pastoral system at nominal cost for the production of forage and fodder for the livestock.
iv) Conservation Contour Trenches:
Where only plantation of fodder trees is required, Conservation Contour Trenches are effective on the moderate slopes as tractors cannot work on these.
2.4. Techniques for Water Harvesting & Conservation for Range Improvement in Plain Areas:
Similarly in the plain areas, water harvesting techniques can be used for grass production. Same techniques as used for crop production can be employed for range improvement with little modification.
i) Roaded Catchments for Improved Grass sowing:
The roaded catchments as explained for crop production can be used for grass sowing. The slope lengths should be equal to grass production strips.
ii) Roaded catchments for Fodder trees:
The roaded catchments for planting of fodder trees with 3.5 m slope lengths on both sides of the central 0.6 m wide drain. Pits are excavated in the drain at the required spacing with pit excavator.
iii) Water spreading for grass sowing:
Water spreading is more useful for perennial grasses and fodder trees than for crops because the moisture in the deeper layers can be extracted by the deep rooted trees, bushes and grasses.
iv) Range Improvement on sandy Deserts:
Water harvesting techniques cannot be employed on the sand dunes and the sandy soils. Special techniques are used for range improvement in sandy deserts.
- Planting of Fodder trees on sand dunes through deep planting and soil amelioration techniques.
- Tuft planting and sowing of grass on sand dunes.
- Sowing of grass through plowing of site for seed bed preparation.
2.5. Water Harvesting & Conservation for Forest/ Fodder Trees:
In dry areas for the improvement of inhabitant’s livelihood, tree crops have much more scope than agriculture crops. Trees help to conserve soil moisture and provide fodder as well as fuel wood. Trees have a deep root system and resist the dry period and droughts by extracting moisture from the deeper soil layers when the grasses dry up and the crops cannot be sown. Trees once established to give sustained production in the difficult climate. Methods such as planting with hand watering, drip irrigation, pitcher irrigation, gravel filled perforated polythene bags and techniques for sand dune stabilization are given with their suitability and financial feasibility. Different water harvesting techniques suitable for the different landscapes is given below:
i) Steep Slopes:
- Boat shaped sowing pits on the steeper slopes for sowing of indigenous trees and bushes.
ii) Moderate Slopes where tractor cannot work:
- Conservation Contour Trenches on moderate slopes.
- V- Shaped Micro-catchments on moderate slopes and gullied area.
- Eye brow Plant pits on moderate slopes.
iii) Gentle Slopes where tractor can work:
- Hillside ditches.
- Conservation Ponds.
- In order to reduce the cost of planting, water harvesting is mechanized by using tractor driven ditcher for excavating hillside ditches and pit excavator for digging plant pits within the ditches.
- The ponds are combined with ditches for treating the slopes and drainage lines.
By the help of new technologies and water harvesting techniques dryland agricultural production can be made suitable and feasible both by economically and technically. Selection of suitable multi-purpose tree species can increase production and improve the rangelands also. These selections of species depend upon the needs of local inhabitants as they get useful fuel wood, fodder, non-timber and other timber from the forests on which their livelihood depends. Selection of multi-purpose tree species for planting is necessary. In case of crop production selection of drought resistant varieties are important for optimum yield. The technology of water harvesting has equal importance for the development of crop production, surface water resource, fruits and fodder.
Water harvesting systems and technologies discussed in this article are suitable for crop and fruit production. However, the use of technology should be complementary to the natural resource use, livelihood needs of the local people and affordability by the farmers or development organizations.