Wastelands are lands that are economically unproductive, ecologically unsuitable and subject to environmental deterioration.
Wastelands are broadly categorized under two groups:
- Barren and Uncultivable Wasteland- It includes lands that cannot be brought under cultivation or economic use except at a very high cost, whether they exist as isolated pockets or within cultivated holdings. They are mostly lands such as hilly slopes, rocky exposures, stony or leached or gully land and sandy deserts.
- Cultivable Wasteland- These lands are cultivable but not cultivated for more than five years. It comprises all lands available for cultivation, but not taken up for cultivation. Next to ‘fallow’ lands, cultivable wastelands are important for agricultural purposes because they can be reclaimed through conservation practices or cultivation or grazing or agro-forestry.
Cause of Wasteland Formation:
Wastelands are formed by natural processes, that include undulating uplands, snow-covered lands, coastal saline areas, sandy areas etc. or by anthropogenic (man-made) activities leading to eroded, saline or waterlogged lands. The major anthropogenic activities leading to wasteland formation are deforestation, overgrazing, mining and erroneous agricultural practices. Desert is one of the major natural wasteland area and any activity relating to the process of desertification is considered also to be one of the major activities underlying the wasteland formation.
Wasteland Reclamation Practices:
With the gradual rise of land resources demand, reclamation of wasteland appears to be one of the major tasks of the country. The reclamation and development of wasteland has four major ecological objectives-
- To improve the physical structure and quality of the marginal soils.
- To improve the availability of good quality water for irrigating these lands.
- To prevent soil erosion. flooding and landslides.
- To conserve the biological resources of the land for sustainable use.
Some important reclamation practices are discussed here-
(I) Afforestation and Reforestation- Afforestation means growing forests over culturable wastelands where there were no forests before due to lack of seeds, trees or other adverse factors. Whereas, reforestation means replanting forests over areas where they were destroyed or degraded by overgrazing, shifting cultivation, excessive felling, forest fires, etc. Restoring forests will not only help in checking soil erosion, floods and waterlogging but also increases land productivity.
(II) Changing Agricultural Practices- Shifting (or Jhoom) cultivation can be replaced by crop rotation, mixed cropping, or developing plantation crops that would improve fertility and support a large population.
(III) Land development and leaching- For reclamation of the salt-affected soil, it is necessary to remove the salts from the root zone which is usually achieved by leaching i.e. by applying an excessive amount of water to push down the salts. After a survey of the extent of salinity problem, soil texture, depth of impermeable layer and water table, land levelling is done to facilitate efficient and uniform application of water. After levelling and ploughing, the field is bunded in 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 the soil depending upon texture. If we use intermittent sprinkling with 25 cm water, it reduces about 90% salinity in the upper 60 cm layer.
(IV) Managing Topography- When water runs downhill, it erodes soil. The faster it runs, the more soil it carries off the fields. Water runoff can be reduced by leaving grass strips in waterways and by-
- Contour Ploughing, that is, ploughing across the hill rather than up and down. The ridges created by cultivation make little dams that trap water and allow it to seep into the soil rather than running off. Contour ploughing is generally combined with strip farming.
- Strip Farming, that is, the planting of different kinds of crops in alternating strips along the contours. When one crop is harvested, the other is still present to protect the soil and keep water from running straight downhill.
- Tied ridges are often useful in areas where rainfall is very heavy. This method involves a series of ridges running at right angles to each other so that water runoff is blocked in all directions and is encouraged to soak into the soil.
- Terracing involves shaping the land to create level shelves of the earth to hold water and soil. The edges of the terrace are planted with soil anchoring plant species. This is an expensive procedure, requiring either much hand labour or expensive machinery, but makes it possible to farm very steep hillsides.
(V) Gypsum Amendment- Amendment of sodic soils with gypsum is recommended for reducing soil sodicity as calcium of gypsum replaces sodium from the exchangeable sites.
(VI) Green-manures, fertilizers and biofertilizers- Application of farmyard manure or nitrogen fertilizers have been found to improve saline soils. Green manuring with dhaincha (Sesbania aculeata) sun hemp or guar has also been reported to improve salt-affected soils. Blue-green algae have been found to be quite promising as biofertilizers for improving salt-affected soils.
(VII) Social Forestry Programmes- These programmes mostly involve strip plantation on the road, rail and canal sides, rehabilitation of degraded forest lands, farm-forestry, wasteland forest development etc.
(VIII) Ecological Succession– Ecological Succession is a natural process of establishment or re-establishment of an ecosystem. This approach is particularly useful in mining and industrial wastelands, where the agriculturally oriented methods fail. Instead of planting fast-growing but vulnerable agricultural grasses, slow-growing native grasses known to be adopted to minerally deficient soils of that area should be planted. This approach has been successful in the reclamation of degraded lands in many parts of the water.