Wasteland reclamation and development in our country falls under the purview of Wasteland Development Board, which works to fulfill the following objectives.
1. To improve the physical structure and quality of the marginal soils.
2. To improve the availability of good quality water for irrigating these lands.
3. To prevent soil erosion, flooding and landslides.
4. To conserve the biological resources of the land for sustainable use.
Some important reclamation practices are discussed here:
(i) Land development and leaching:
For reclamation of the salt affected soil, it is necessary to remove the salts from the root-zone which is achieved by leaching i.e., by applying excess amount of water to push down the salts.
After a survey of the extent of salinity problem, soil texture, depth of impermeable layer, water table-land leveling is done to facilitate efficient and uniform application of water. After leveling and ploughing, the field is divided into small plots and leaching is done.
In continuous leaching, 0.5 to 1.0 cm water is required to remove 90% of soluble salts from each cm of soil depending upon texture. If we use intermittent sprinkling with 25 cm water, it reduces about 90% salinity in upper 60 cm layer.
This is required for water logged soil reclamation where excess water is removed by artificial drainage.
(a) Surface drainage:
This is used in areas where water stands on the fields after heavy rains by removing ditches to run-off the excess water. Usually 30-45 cm deep ditches lying parallel to each other at 20-60 cm distance are able to remove 5 cm of water within 24 hours.
(b) Sub-surface drainage:
Horizontal sub-surface drainage is provided in the form of perforated corrugated PVC pipes or open jointed pipes within an envelope of gravel 2-3 m below the land surface. Chances of evaporation of water leading to accumulation of salt almost become nil in this method.
(iii) Irrigation practices:
Surface irrigation with precise land leveling, smoothening and efficient hydraulic design help to reduce water logging and salinity. High frequency irrigation with controlled amount of water helps to maintain better water availability in the upper root zone. This and frequent irrigations have been found to be more useful for better crop yield when the irrigation water is saline as compared to few heavy irrigations.
(iv) Selection of tolerant crops and crop rotations:
Tolerance of crops to salts is found to range from sensitive, semi-tolerant, and tolerant to highly tolerant. Barely, sugar beet and date palm are highly tolerant crops which do not suffer from any reduction in crop yield even at a high salinity with electrical conductivity (EC) Wheat, sorghum pearl, millet, soya been, mustard and coconut are salt tolerant crops. Rice, millets, maize, pulses, sunflower, sugarcane and many vegetables like bottle gourd, brinjal etc. are semi-tolerant. These different crop combinations can be grown on saline soils.
(v) Gypsum amendment:
Amendment of sodic soil with gypsum is recommended for reducing soil sodicity as calcium of gypsum replaces sodium from the exchangeable sites.
(vi) Green manures, fertilizers and bio-fertilizers:
Application of farmyard manure or nitrogen fertilizers has been found to improve saline soils. Green manuring with dhaincha, (Sesbania oculeata), sun hemp or guar have also been reported to improve salt-affected soils. Blue green algae have been found to be quite promising as bio-fertilizers for improving salt- affected soils.
(vii) Afforestation programme:
The National Commission on Agriculture (NCA) launched several afforestation schemes in the with plan to cope up with the problem of spreading wasteland Development Board, in the Ministry of Environment and Forests has set a target of bringing 5 million hectares of wasteland annually under firewood and fodder plantation.
(vii) Social forestry programme:
These programs mostly involve strip plantation on road, rail an canal sides, rehabilitation of degraded forest lands, farm forestry, wasteland, forest development etc.