«Auroville: Wasteland reclamation through rehabilitation of eroded soil 1. GENERAL INFORMATION 1.1 Title of practice or experience Auroville: ...»
Auroville: Wasteland reclamation through
rehabilitation of eroded soil
1. GENERAL INFORMATION
1.1 Title of practice or experience
Auroville: Wasteland reclamation through rehabilitation of eroded soil
1.2 Category of practice/experience and brief description
The practices described below relate to two series of experiments in environmental regeneration conducted in Auroville, an international cornmunity
located in coastal Tamil Nadu, India. Selected plant species were used to rehabilitate eroded plots of (a) red lateritic soils, and (b) saline-alkaline shallow black cotton soils.
Similar experiments have been replicated in other places in and around Auroville, pointing to the possibility of using plants to hasten wasteland reclamation.
1.3 Name of person or institution responsible for the practice or experience Bernard Declercq, Auroville
1.4 Name and position of key or relevant persons or officials involved As in 1.3 above
1.5 Details o institution f (a) Address: Aurobrindavan, Auroville 605 101, Tamil Nadu, India (b) Telephone: ++ (91) (0413) 72332 (c) Fax:++ (91) (0413) 62274
AUROVILLE: WASTELAND RECLAMATION THROUGH REHABILITATION OF ERODED SOIL
1.6 Name of person and/or institution conducting the research As in 1.3 above
1.7 Details of research person/institution As in 1.5 above THE
2. THE PROBLEM OR SITUATION BEING ADDRESSED
PRACTICE/INNOVATIVE EXPERIENCEIt has been estimated that about one-third of India’s lands suffer, in one way or another, from severe degradation. Rendered unproductive by the destructive forces of wind and water erosion or by salinity and waterlogging, these vast stretches of land have been abandoned and neglected, while food production centres around a few fertile pockets.
According to the 1985 Report of the National Remote Sensing Agency in Hyderabad, 53.3 million hectares of land are to be considered as wastelands.
The situation has not improved since and more recent figures put the number at 69 million hectares. The drylands and marginal lands, where for ages millets and pulses were grown, have suffered the most in the last three decades. Small and medium farmers, unable to make ends meet and drawn to the ever-growing cities, gradually left these lands to the destructive forces of wind and water erosion.
The common grazing lands have suffered even more. With the introduction of short-stemmed, so-called high-yielding varieties, fodder became scarce and the already overstretched grazing lands have consequently been utterly ravaged.
Food production is now centred around big dams in a few districts of the various Indian states. But even there, degradation has become a major problem.
On level lands with convenient road access and assured water availability, urban and industrial development stands in competition with agriculture.
Hence there is growing pressure on the marginal lands to produce food crops which may be very different from the crops grown earlier on them.
Various conventional methods are employed either to bring these lands to a better state of preparedness by bulldozing them into a desired size and topography or, curiously enough, to provide clones of a few tree species such as eucalyptus or, better, genetically engineered plants which must be able to grow in a ravaged land. Putting a bandage on a wooden leg is the solution offered.
The practices described below were formulated with the conviction that
PART IV: ENVIRONMENTALLY-SOUND PRACTICES AND198 TECHNIQUES meeting the challenge of food security, given a growing population, does not rest on expensive and high technology to stretch the limits of food production in better-endowed areas, but rather on restoring the productive capacity of the extensive wastelands.
Land reclamation commonly fails when carried out as a ‘single-phased’ attempt. Survival rates in many afforestation programmes are abysmally low, even when the plantations are of indigenous species. This is because the condition of the land is far worse now than the native condition in which local vegetation/crops once thrived. The experiments carried out address the problem of how to initiate regenerative processes on degraded lands and whether it is possible to use certain plant species for this.
The specific objective of the experiments was to regenerate degraded lands
in two very different soil zones:
(a) red lateritic soils, and (b) saline-alkaline shallow black cotton soils.
Both the areas suffer from severe environmental problems. In the red lateritic soil area, erosion had washed away all the topsoil, carved out gullies, and left behind a barren, stony, rugged expanse. The black clayey soil area suffered from severe alkali formation due to previous agricultural malpractices, trampling and denudation. A white crust of 3-cm thickness was observable on the worst affected portions and there was no vegetation whatsoever.
Rehabilitation of such lands was successful through a judicious use of plants and conservation measures.
Care and reverence for the land, the crops that it yields, the seeds, respect for the animals and all forms of life, for the rain, water in whatever form, in short, for the fostering Mother who has nourished and sheltered us for centuries is the only way which will help humanity out of its environmental and thus agricultural impasse.
3. DESCRIPTION OF THE PRACTICE/INNOVATIVE EXPERIENCE AND ITS MAIN FEATURES
The technology presented here, combined with other complementary measures like soil and water conservation, makes it possible to regenerate for crop production even the most degraded lands very effectively and inexpensively. The combined measures present an alternative to the conventional reclamation methods (for instance, bulldozers, soil amendments, drainage using pipes, etc.) which are expensive and most often do not provide durable solutions. The only serious inputs are in fact time and care.
The practices described below concern rehabilitation work on sites representative of two types of soils:
AUROVILLE: WASTELAND 199
RECLAMATION THROUGH REHABILITATION OF ERODED SOIL(a) red lateritic soils, and (b) alkaline black cotton soils.
Both the sites are situated in Auroville, an international community located in the Vanur Block of VRP District, Tamil Nadu, India.
THE REGENERATION OF RED LATERITIC SOILSDescription of the area An area of three acres was earmarked for regeneration in a red soil area where erosion had carved out, in some places, huge gullies. The topsoil had entirely vanished. The subsoil on which the reclamation work was to be done, consisted of 80% stones and pebbles, with 20% soil having a pH of 5.2. The entire area before regeneration was, practically speaking, barren.
The average annual rainfall in the area is 1,200 mm, most of which is received in the months of October-November. Rainy spells are heavy and unevenly distributed - at times producing 200-300 mm of rain in 24 hours.
The aim was to regenerate the land for planting of timber wood (Dalbergia latifolia, Pterocarpus santalinus, Kigelia pinnata), non-edible oil seeds like neem (Azadirachta indica) and minor fruits like Diospyros melanoxylon. Attempts at reforestation directly with these species had been made earlier but were unsuccessful. Their failure indicated that the environment and soil condition was not yet conducive to their growth even though most of the species tried out were indigenous. Experiments were therefore conducted, as described below, in, which select plant species were used to serve as ‘pioneers’ for improving the environment and soil condition prior to the planting of these desired timber and minor fruit trees.
Soil and water conservation As a first step, soil and water conservation measures were undertaken.
These consisted of (a) contour bunds at regular intervals (earth bunds stabilised with local grasses), and (b) water harvesting ponds in the gullies (made by constructing simple earth check dams).
Identification of pioneer species
(a)can grow in very poor soils under adverse conditions (b)fast-growing (c)can produce large amount of biomass in a short time (d)grows easily from seed or easy to plant, without need for pitting or any other care (e) drought- or flood-resistant (f) capable of recovery after stress (g) deep root system (h) nitrogen fixing (i) ability to unlock or accumulate nutrients from subsoil reserves (j) unpalatable to livestock (k) economically valuable, even if only to a minor degree Four species of plants with at least five of the abovementioned characteristics were accordingly selected for trials as pioneers.
Two exotic species: Acacia holosericea (coleii) (first introduced in India by Auroville foresters); and Stylosanthes hamata (grown by some farmers as a fodder crop).
Two indigenous species: Dodonaea viscosa (grows wild here and there in surrounding areas); and Cassia auriculata (grows wild nearby, used for medicinal purposes and green manure).
Seed requirement Seeds of Stylosanthes hamata were purchased from outside while the rest
were collected locally. The seed rates used were as follows:
Acacia holosericea (coleii) 1 kglacre Stylosanthes hamata 5 kglacre Dodonaea viscosa ad libidum 1/2 kglacre Cassia auriculata Method of sowing Untreated mixed seeds of these species were broadcast on the barren land during the summer months. Only Stylosanthes hamata was sown at the onset of the monsoon rains. Broadcasting of seeds turned out to be a suitable technique because the land surface was covered with stones and pebbles which protected the broadcast seeds from being washed away with the rains. The seeds which did get carried off with the rains, accumulated in the trenches of the bunds. An alternative practice recommended for areas where the surface of the land is not as rough is to make, with a stick, small furrows in the soil, in which the seeds are sown.
AUROVILLE: WASTELAND RECLAMATION THROUGH REHABILITATION OF ERODED SOILObservations Stylosanthes hamata The Stylosanthes hamata was the first to germinate. The growth rate was excellent considering the soil condition. A fairly dense stand of plants developed, measuring between 10 and 15 cm height after six months of growth.
After three years, a dense carpet of Stylosanthes hamata covered the whole area, except in places where waterlogging occurred. The Stylosanthes hamata was left uncut and quickly spread to adjacent areas. It now forms a lush, selfseeding soil cover. It is, however, possible to harvest the Stylosanthes hamata for fodder in the second year of growth.
After the rains started, it took one month for the seeds to start germinating. Some seeds germinated even after one year, with the onset of the next rainy season. Plants grew up to 1 m in height in the space of a year. Some exceptional plants even produced seeds in their very first year. Within the space of three years, the Acacia holosericea had grown into dense bushes reaching a height of 3 to 4 m. At the end of the third year, a considerable amount of leaf litter had accumulated on the soil surface. In the fourth year, the bigger trees were ready for harvesting as firewood.
The broadcast seeds started germinating 14 days after the rains commenced. They grew up to 20 cm in the first year. In the second year, two to three plants per square metre were observed, with an average height of 75 cm.
Some leaf litter started forming in the second year. The soil development under three year-old Dodonaea viscosa plants was remarkable and these spots were found to be ideal for direct sowing of secondary species. From the third year onwards Dodonaea viscosa started spreading on its own by self-seeding.
The Dodonaea viscosa plants were not harvested except occasionally as mulch material. They could be harvested for firewood from the third year onwards.
Cassia auriculata Only a few plants grew, and with great difficulty at that. Cassia auriculata can thus not be considered a suitable pioneer in this particular area.
PART IV: ENVIRONMENTALLY-SOUND PRACTICES AND TECHNIQUESPlanting of secondary species After the third year of growth of these pioneers, the environment and the soil condition had improved considerably. There was sufficient protection against the desiccating summer winds, the soil was covered with plenty of organic matter and aerated as well by the root activity of the pioneers. Subsequently, planting of the secondary species was commenced. Secondary species were indigenous trees either bearing fruits or oilseed, or for use as timber.
In this case, several species of trees were planted, of which the following performed very well: Pterocarpus santalinus, Dalbergia latifolia, Tectona grandis, Khaya senegalansis, Diospyros rnelanoxylon, Hardwickia binata, Azadirachta indica, Terrninalia tornentosa, Terrninalia bellirica, Ernblica officinalis, Syzygium cumini, Anacardium occidentale.
Nursery techniques, planting and after-care
Various methods were tried out to raise these trees:
(a) plastic bags (b) nursery beds - planting bare-rooted seedlings (c) direct sowing/dibbling (d) broadcasting pelletted seeds It was found that no general rule regarding the suitability of any one method over the others could be made. Species respond differently and various other factors like timing and working convenience are also at play. A combination of these methods, based on experience, was found to be the most practical approach. For instance, Hardwickia binata grows best if sown in situ.
Pterocarpus santalinus is hard to germinate in the nursery but seedlings which are found abundantly under a mother tree can be carefully dug out and planted.
Santalum album needs to be raised in plastic bags as the seeds, with their short viability, have to be sown immediately and this might not coincide with the monsoon.