Chapter 10 — Natural Resources

A natural resource is any material or energy from nature that people use to satisfy their needs. Air, water, sunlight, soil, forests, wildlife, minerals, coal, petroleum and natural gas are all natural resources. Some are used as they are, like the air we breathe; most are changed by human work into food, houses, cloth, fuel and machines. The wealth of a country and the health of its people depend on how rich its natural resources are and, more importantly, on how wisely they are used.

Natural resources are divided into two classes by how quickly nature replaces them. Renewable resources are those that nature renews continuously or within a human lifetime. Sunlight, wind, tides, flowing water, air, soil, forests, wildlife, fish and crops are renewable. Some, like sunlight and wind, are inexhaustible whatever we do. Others, like forests, fish and ground water, are renewable only if we use them no faster than they grow back; cut a forest faster than it regrows or pump a well faster than rain refills it, and a renewable resource behaves like a non-renewable one and runs out.

Non-renewable resources are those that formed over millions of years and cannot be replaced once used. Coal, petroleum, natural gas, and minerals such as iron, copper, bauxite, gold and uranium are non-renewable. The Earth holds only fixed stocks of them. Some, like metals, can be recycled and used again; fossil fuels, once burnt, are gone for ever.

Resources may also be classed as biotic, obtained from living things (forests, animals, fish, fossil fuels formed from ancient life), and abiotic, from non-living things (air, water, soil, minerals). Another useful division is between actual resources whose quantity is known and which are being used, and potential resources which exist but are not yet used, such as the wind energy of the Rayalaseema hills or the solar energy falling on every roof.

India uses its resources under great pressure. The country has about seventeen per cent of the world's people on about two and a half per cent of its land, and consumption is rising as incomes rise. Ground water tables are falling in Anantapur and Chittoor, forests have been cleared across the Eastern Ghats, and coal reserves are being mined faster every year. The rest of this chapter examines four resources in turn, soil, water, forests and fossil fuels, and asks how each can be used so that it lasts.

Soil is the thin loose layer on the surface of the land in which plants grow. Though it looks ordinary, it is one of the most precious resources, because nearly all our food comes from it and it takes hundreds of years to form. Soil is made from rock by the process of weathering. Sun heats rock by day and it cools by night, so it cracks. Water enters the cracks, freezes on cold nights and expands, splitting the rock further. Rain, wind and flowing water grind the pieces. Rainwater with dissolved carbon dioxide slowly dissolves minerals. Lichens and mosses grow on the bare rock and secrete acids; the roots of plants force their way into cracks. Over centuries the rock is reduced to fine particles of sand, silt and clay.

Rock particles alone are not soil. Living organisms complete it. Dead plants and animals are broken down by bacteria, fungi and earthworms into dark humus, which mixes with the mineral particles, holds water, binds the particles into crumbs and slowly releases nutrients. A handful of good soil holds more living organisms than there are people on Earth. It is estimated that it takes about 200 to 1,000 years to form one centimetre of fertile topsoil.

A vertical cut through soil shows layers called horizons. The top layer, topsoil (A horizon), is dark, rich in humus and roots, and is where most of the fertility lies; it is usually only 15 to 30 cm deep. Below it the subsoil (B horizon) has less humus, more clay and minerals washed down from above. Below that lies weathered rock and finally the solid bedrock.

Soils differ with the rock they came from and the climate. Andhra Pradesh has red soils over most of Rayalaseema and the uplands, formed from granite and gneiss, low in humus and nitrogen; black cotton soils in Kurnool, Guntur and Prakasam, formed from basalt, rich in clay and lime, which swell when wet and crack when dry and hold moisture well; alluvial soils in the Krishna and Godavari deltas, deposited by the rivers, deep and fertile and ideal for paddy; and sandy coastal soils along the shore. Laterite soils occur in the wetter parts of the Eastern Ghats.

Fertility is the ability of soil to supply plants with water and nutrients. It depends on the amount of humus, the balance of sand, silt and clay (a mixture called loam is best), the presence of nitrogen, phosphorus, potassium and other elements, the pH, and the population of soil organisms. Fertility is lost by erosion of topsoil, by continuous cropping without returning organic matter, by waterlogging and salt accumulation from over-irrigation, and by excessive chemical fertiliser and pesticide use, which kills soil life. It is restored by adding compost and green manure, rotating crops, growing legumes and resting the land.

Soil erosion is the removal of the topsoil by wind, water or human activity faster than it can be formed. Since the topsoil holds nearly all the humus, nutrients and soil life, its loss leaves behind poor subsoil or bare rock on which little can grow. Erosion is happening on a huge scale; India is estimated to lose over five billion tonnes of soil every year, and much of the land of Rayalaseema and the Telangana border districts is already degraded.

The chief agent of erosion is running water. When rain falls on bare ground, the drops strike the soil and loosen it (splash erosion). The water then flows over the surface, carrying away a thin film of soil evenly over the field (sheet erosion). Where the flow concentrates it cuts small channels (rill erosion), and these deepen into gullies that make the land useless, as in the ravines along the Chambal and in parts of the Godavari valley. Rivers in flood cut their banks and carry away fields. The heavier the rain and the steeper the slope, the faster the erosion.

Wind erodes dry, loose soil in areas with little vegetation, as in the arid parts of Anantapur, lifting the fine particles as dust storms and leaving coarse sand behind. Along the coast wind drives sand dunes inland over fields.

Erosion is a natural process, but human activity has multiplied it many times. Deforestation removes the canopy that breaks the force of rain and the roots that bind the soil. Overgrazing by too many cattle, sheep and goats strips the grass cover and the hoofs loosen the soil. Faulty farming, such as ploughing up and down a slope, leaving fields bare between crops, and burning crop residue, exposes the soil. Shifting cultivation on hill slopes, mining, road building and construction all leave bare, loosened earth for rain to carry away.

The effects of erosion reach far beyond the field. Loss of topsoil reduces crop yields and eventually turns farmland into wasteland, a process called desertification. The eroded soil is carried into tanks, reservoirs and rivers, where it settles as silt, reducing their storage capacity; the Tungabhadra and Srisailam reservoirs have lost a significant part of their capacity to silt. Silt-laden rivers flood more easily. Eroded soil carries fertiliser and pesticide into water bodies. And because bare eroded land does not absorb rain, less water sinks in to recharge wells, so erosion and water scarcity go together.

The key to preventing erosion is vegetation cover: a layer of plants, grass or crop residue on the soil intercepts the rain, slows the run-off, and binds the soil with roots. Every method of soil conservation, described in the next section, works by keeping the soil covered or by slowing the water.

Soil conservation means using and managing land so that the soil is not lost and its fertility is maintained. Farmers, forest departments and village communities in India have developed many methods, and most of them are simple.

Contour ploughing. On sloping land, ploughing along the contour, that is across the slope at the same height, instead of up and down, makes each furrow a small dam that holds water and soil. Rain sinks in instead of running off. Contour bunding builds low earthen ridges along the contours at intervals down the slope to stop run-off; it is common on the red soils of Rayalaseema. Terracing cuts a steep slope into a series of flat steps with retaining walls, used on hills in the Eastern Ghats and the Araku valley for coffee and paddy.

Strip cropping grows alternate strips of an erosion-permitting crop like maize and an erosion-resisting close-growing crop like groundnut or grass along the contour, so the soil washed from one strip is caught in the next. Crop rotation and growing legumes keep the soil covered and add nitrogen. Mulching covers the soil between plants with straw, leaves or crop residue, which breaks the force of rain, keeps the soil moist and adds humus as it rots. Cover crops such as horse gram or sunn hemp are grown in the off season simply to protect the soil.

Afforestation, planting trees on bare hills and wasteland, is the most powerful long-term method; roots hold the soil and the litter builds humus. Shelter belts of trees planted in rows across the wind direction reduce wind erosion in dry areas and along the coast, where casuarina belts protect the fields behind them. Controlled grazing, with limits on the number of animals and rotation of pastures, allows grass to recover. Gully control uses check dams of stone or brushwood across small gullies to trap silt and let the gully fill and grass over.

The story of Ralegan Siddhi in Maharashtra shows what a village can do. In 1975 it was a drought-hit, eroded village with failing crops. Under the leadership of Anna Hazare the villagers banned free grazing and tree cutting, planted trees on the hills, built contour bunds and check dams and revived the tanks. Within ten years the water table rose, cropped area multiplied and the village became prosperous. Similar work in Hiware Bazar and in watershed villages of Anantapur district shows that soil and water conservation must go together: whatever holds the soil also holds the rain.

Government schemes support these methods. The watershed development programme treats a whole catchment, from the ridge to the valley, with bunds, trenches, plantations and check dams. The rural employment guarantee scheme pays villagers for building such structures. But the methods work only when the community agrees to protect what it has built and to stop free grazing and tree cutting on the treated land.

About seventy-one per cent of the Earth's surface is covered by water, but ninety-seven per cent of it is salt water in the oceans. Of the three per cent that is fresh, most is frozen in glaciers and ice caps; less than one per cent of all water is available as liquid fresh water in rivers, lakes and ground water. This small fraction must serve every plant, animal and person on land. Water is renewable because of the water cycle: the Sun evaporates water from the seas and land, the vapour rises and cools to form clouds, and rain and snow return it to the surface, where it flows in rivers back to the sea or sinks into the ground. Plants draw water from the soil and release it from their leaves as vapour (transpiration), which also feeds the clouds.

India receives almost all its water from the monsoon rains, but they fall only in about three or four months and unevenly across the country. Andhra Pradesh averages about 900 mm a year on the coast but only about 550 mm in Anantapur, one of the driest districts of India. The rain that falls is collected in three ways: surface water in rivers (Godavari, Krishna, Pennar, Vamsadhara), tanks and reservoirs (Nagarjunasagar, Srisailam, Somasila); ground water that seeps through soil and rock and collects in porous layers called aquifers, reached by wells and bore wells; and, along the coast, desalinated sea water in a few places.

Water is used for drinking and household needs, for irrigation, which takes about eighty per cent of all water used in India, for industry and for generating electricity. As population and farming grew, demand rose beyond what the monsoon and the ground could supply. The result is a water crisis with several causes. Over-pumping of ground water by millions of bore wells has lowered the water table by tens of metres in Rayalaseema; wells that once struck water at 20 m now go to 200 m and many are dry. Tanks that stored monsoon water for centuries have silted up, been encroached or fallen into disrepair. Deforestation has reduced the amount of rain that soaks into the ground. Pollution by sewage, industrial waste and pesticides makes much surface water unfit to use. And water is wasted by flooding fields for crops that could be grown with drip irrigation, and by leaking pipes in towns.

The consequences are drying rivers, drinking water carried by tankers and trains to villages and towns in summer, conflicts between states over river water, salt water entering coastal aquifers where fresh water was pumped out, and fluoride-rich deep water in Nalgonda-type areas causing bone disease. The solutions lie in catching more of the rain where it falls, using less, and cleaning what we discharge, which the next sections describe.

A watershed is an area of land from which all the rain drains to a single stream, river or lake. Every hill slope, valley and field belongs to some watershed. If the land in a watershed is bare and hard, rain rushes off it in a few hours, carrying soil, causing floods below and leaving nothing behind for the dry months. If the land is covered and shaped to hold water, the same rain soaks in, fills the soil, recharges the wells and feeds the streams for months. Watershed management is the planned treatment of a whole catchment so that every drop of rain is made to stay where it falls as long as possible, from the ridge at the top to the valley at the bottom.

The treatment follows the slope. On the upper slopes, which are usually forest or waste land, contour trenches are dug and trees and grasses are planted; the trenches catch the run-off and the plants hold the soil. On the middle slopes, where the fields are, contour bunds and field bunds hold water in the fields and gully plugs of loose stone stop the small channels from growing. In the drainage lines, small check dams of earth or masonry hold back the stream, so that water stands behind them for weeks and sinks in to recharge the wells. Percolation tanks are built where the soil is porous purely to let water sink into the ground, and farm ponds store water for protective irrigation. The old village tanks are desilted and their feeder channels cleared. Free grazing is stopped and trees are protected.

The results appear within a few seasons. Wells that were dry hold water; the stream flows for more months; a second crop becomes possible; fodder and fuel wood return; and migration out of the village in summer stops. Andhra Pradesh was among the first states to take up watershed development on a large scale in the 1990s, especially in the drought-prone districts of Anantapur, Kurnool, Kadapa, Chittoor and Prakasam, through programmes run with village watershed committees. The state's Neeru-Meeru (Water and You) programme in 2000 built lakhs of small water-harvesting structures with village labour. Studies of treated watersheds in Anantapur found ground water levels rising by two to four metres and cropped area increasing by a third.

The success of watershed management depends less on engineering than on people. The whole village must agree to the plan, share the work, protect the plantations from goats and fire, and share the water fairly, because the benefit of a check dam built on one farmer's land appears in the wells of the farmers below. Villages where the watershed committee is strong keep their structures maintained; where it is weak the bunds are breached and the trees are cut within a few years. This is why every watershed programme now begins by forming a committee and a village fund.

Rainwater harvesting is the collecting and storing of rain where it falls, for direct use or for recharging the ground, instead of letting it run away. It is the oldest and cheapest way of solving water scarcity and works in a city flat as well as in a village. Rain is collected from two kinds of surface: rooftops and the ground surface.

In rooftop rainwater harvesting, the rain falling on the roof of a house or school is led by gutters and pipes into a storage tank, passing through a simple filter of sand, gravel and charcoal, and used for drinking or washing; or it is led into a recharge pit or a disused bore well so that it sinks into the ground and raises the water table. A roof of 100 square metres in a place with 800 mm of rain receives about 80,000 litres in a year, enough for a family's drinking and cooking needs. Many towns in Andhra Pradesh now require rainwater harvesting structures in new buildings. Chennai made rooftop harvesting compulsory in 2003, and within a few years the ground water level in the city rose noticeably.

On the ground, rain is harvested by percolation pits, recharge trenches along the boundary of a field, farm ponds, check dams and the village tank itself. In coastal districts, small dams stop fresh water from running into the sea and keep sea water from entering the aquifer.

India has a rich tradition of harvesting rain, developed over centuries to suit each region. The tanks (cheruvu) of Andhra Pradesh and Tamil Nadu, thousands of them built by kings and villages, catch monsoon run-off behind an earthen bund and release it through sluices to the fields below, with the overflow feeding the next tank in a chain. The kere of Karnataka and the eri of Tamil Nadu are the same idea. In Rajasthan, johads are small earthen check dams; kunds are covered underground tanks fed by a saucer-shaped catchment; bawris are step wells. Khadin in Jaisalmer holds run-off on a field so that a crop is grown on the stored moisture. In the Himalayan states, kuls are channels that carry glacier melt to the fields. In Meghalaya, bamboo pipes drip water to betel plantations. In Kerala, surangams are horizontal tunnels dug into hillsides to tap ground water.

Many of these systems fell into neglect when canals and bore wells arrived, but they are being revived. In Alwar district of Rajasthan, the organisation Tarun Bharat Sangh helped villages rebuild thousands of johads from 1985 onwards; wells refilled, five dry rivers began to flow again through the year, and the forest cover increased. The lesson for Andhra Pradesh is to restore its tank chains, which are its own johads, and to add rooftop and field harvesting to them.

Since Independence India has built thousands of large dams to store river water, generate electricity and control floods. In Andhra Pradesh the Nagarjunasagar dam on the Krishna, completed in 1967, irrigates about nine lakh hectares in Guntur, Prakasam, Nalgonda and Khammam; the Srisailam dam generates hydroelectricity; the Prakasam barrage at Vijayawada and the Dowleswaram barrage on the Godavari feed the delta canals; and the Polavaram project on the Godavari is under construction. Large dams have real benefits: assured irrigation that turned dry land into two-crop farmland, cheap clean electricity, water for cities and industry, control of floods, fisheries and navigation.

But large dams also have serious costs, and the chapter asks us to weigh them honestly. First, displacement: a reservoir drowns villages, fields and forests, and the people, often tribal families, must move. Nagarjunasagar submerged dozens of villages; Polavaram will displace over one lakh people, many of them Koya and Konda Reddi tribals. Rehabilitation has often been poor. Second, loss of forest and wildlife: the submerged area was usually forest, and the Srisailam reservoir lies within a tiger reserve. Third, siltation: the reservoir fills with silt from an eroded catchment and its capacity shrinks. Fourth, downstream effects: with the flow trapped, the river below carries less water and silt, deltas erode, mangroves die and fish migration is blocked. Fifth, waterlogging and salinity in the command area when canal water is applied too generously, as in parts of the Nagarjunasagar left canal. Sixth, the unequal sharing of benefits: farmers at the head of the canal take the water and those at the tail get little. And large dams are costly and slow; Polavaram has been under construction for more than a decade.

Movements such as the Narmada Bachao Andolan against the Sardar Sarovar dam raised these questions nationally and led to better rules on rehabilitation and environmental clearance. The alternative view is not to reject all dams but to prefer many small structures, watershed work, tank restoration and efficient use of water, which give most of the benefit with far less damage, and to build large dams only after their costs are counted and the displaced are properly resettled.

Water use itself can be made more efficient. Drip irrigation delivers water to the root of each plant through pipes and saves half the water of flood irrigation; sprinklers suit groundnut and vegetables; laser-levelled fields need less water; and growing crops suited to the rainfall, such as millets and pulses in Rayalaseema instead of paddy, reduces the demand for bore wells. Andhra Pradesh's micro-irrigation programme has brought drip to lakhs of hectares of fruit and vegetable crops in Rayalaseema.

A forest is a large area covered mainly by trees, with its own community of shrubs, herbs, climbers, fungi, animals, birds and insects. Forests are among the most valuable of all renewable resources, because they supply so many goods and services at once. About twenty-one per cent of India's land is forest; Andhra Pradesh has about twenty-three per cent, mostly in the Eastern Ghats and the Nallamala hills, ranging from moist deciduous forest in the Godavari valley to dry deciduous and thorn forest in Rayalaseema and mangroves at Coringa in the Godavari estuary.

The direct uses of forests are the products we take from them. Timber for houses, furniture and boats comes from teak, sal, rosewood and red sanders; the red sanders of the Seshachalam hills in Kadapa and Chittoor is so valuable that it is smuggled. Fuel wood is still the main cooking fuel of many rural families. Bamboo gives paper, baskets and building material. Minor forest produce such as tendu leaves for beedis, gum karaya, tamarind, honey, soapnut, mahua flowers, tubers and medicinal plants supports the livelihood of the tribal people of the Eastern Ghats. Fodder for cattle, fruit, resin, lac, silk from tasar caterpillars, and raw material for paper, rayon, sports goods and matches all come from forests. Hundreds of medicines, from quinine to the cancer drugs from the Himalayan yew, were first found in forest plants.

The indirect uses, the services, are even more important. Forests are the great regulators of water: the canopy breaks the force of rain, the litter and roots soak it in and release it slowly to streams and wells, so a forested catchment gives water all year and a bare one gives floods and then drought. They prevent soil erosion and build fertile soil from their fallen leaves. They absorb carbon dioxide and release oxygen, moderating the climate; their transpiration cools the air and adds moisture that brings rain. They are the home of most of the world's species, the gene bank from which new crops and medicines come. They shelter the tribal communities who live within them. And they have cultural and recreational value, from sacred groves to the pilgrim forests of Tirumala.

Because forests take decades to grow and the services they give are not sold in any market, they are undervalued and easily destroyed for the short-term gain of timber, farmland or a mine. The next section examines this destruction and its consequences.

Deforestation is the clearing of forest land for other uses, or the degradation of a forest by cutting faster than it can regrow. India lost most of its forest cover during the last two centuries, first to the railways and shipbuilding of the colonial period, then to the expansion of farming, and continues to lose it today to development projects, although planting has slowed the net loss.

The causes are several. Expansion of agriculture is the largest: forest is cleared for fields, and on hill slopes shifting cultivation (podu in Andhra Pradesh, jhum in the north-east) burns a patch of forest, grows crops for two or three years and moves on; when the population is small the forest regrows in the fallow years, but with more people the cycle shortens and the land degrades. Timber and fuel wood cutting, both legal and illegal, thins the forest. Mining for bauxite, iron and coal, as in the Eastern Ghats and Singareni belt, strips the forest and dumps waste on it. Dams submerge valleys of forest. Roads, railways, industries and townships take forest land and open the interior to further cutting. Overgrazing prevents regeneration by eating the seedlings. Forest fires, most started by people, destroy undergrowth and young trees.

The consequences follow from the services forests give. Soil erosion increases many times on the bare slope, and the eroded soil silts up tanks and reservoirs. Floods worsen because rain runs off instead of soaking in, and droughts worsen because the ground is not recharged; streams become seasonal. Rainfall may fall in the region as transpiration decreases. Carbon dioxide stored in the wood goes into the air, adding to global warming. Wildlife loses its habitat: the tiger, the elephant, the great Indian bustard and hundreds of less famous species have declined as forests shrink and are broken into isolated patches. Tribal communities lose their livelihood and culture. And desertification spreads as the degraded land loses its soil and its capacity to hold water. In the long run, the value of the timber taken is far less than the value of the services lost.

Laws try to check deforestation. The Forest (Conservation) Act of 1980 requires central approval and compensatory planting before forest land is diverted, and the Forest Rights Act of 2006 recognises the rights of forest-dwelling communities and gives them a say in its protection. But laws are only as strong as the communities and officials who enforce them, which is why the movements and joint management described in the next section matter.

Forests are best protected by the people who live near them, and India's history has several examples. The Chipko movement began in 1973 in the Garhwal Himalaya, when the villagers of Mandal, and later Reni under Gaura Devi, hugged (chipko) the trees to stop contractors from felling them, saying that the forest was their water, soil and livelihood. The movement, led by Chandi Prasad Bhatt and Sunderlal Bahuguna, spread through the hills and led to a ban on commercial felling in the high Himalaya. It follows the much older example of the Bishnoi community of Rajasthan, 363 of whom, led by Amrita Devi, gave their lives in 1730 to protect khejri trees from the axes of the king's men. The Appiko movement of 1983 in Karnataka copied Chipko in the Western Ghats.

In Andhra Pradesh, forest conservation with community participation takes the form of Joint Forest Management (JFM), introduced across India after 1990. A village bordering a degraded forest forms a Vana Samrakshana Samithi (VSS), a forest protection committee, with the forest department. The villagers protect the assigned patch from cutting, grazing and fire, plant and tend trees, and in return get all the minor forest produce, fuel wood and fodder, and a share of the timber when it is harvested. Andhra Pradesh had over seven thousand VSSs covering more than fifteen lakh hectares by the early 2000s, one of the largest JFM programmes in the country. In many places the results are visible: degraded scrub has grown back into forest, streams flow longer and the villagers earn from bamboo and other produce.

Other conservation measures include afforestation and social forestry programmes, which plant trees on village commons, road sides, canal banks and wasteland, so that fuel and fodder needs are met without cutting the natural forest; the Vanam-Manam and Haritha Haram type drives of the two Telugu states have planted crores of seedlings, though survival depends on protection from grazing. Protected areas, national parks, sanctuaries, tiger reserves and biosphere reserves, keep whole forest ecosystems intact; in Andhra Pradesh these include the Nagarjunasagar-Srisailam Tiger Reserve, Papikonda National Park, Sri Venkateswara National Park, Coringa sanctuary and the Seshachalam biosphere reserve. Reducing demand for forest products also helps: cooking gas and improved stoves in place of fuel wood, recycled paper, treated bamboo and plantation timber in place of forest teak.

The principle in all these is the same. A forest survives when those who benefit from its standing are stronger than those who benefit from its cutting, and when the people who protect it receive a fair share of what it gives.

Fossil fuels are fuels formed from the remains of plants and animals that lived millions of years ago, buried under sediment and changed by heat and pressure over geological time. They are coal, petroleum and natural gas. They hold the energy that ancient plants captured from the Sun, and since the Industrial Revolution they have powered the world. They are the clearest example of a non-renewable resource: what took three hundred million years to form is being burnt in a few centuries.

Coal formed from the trees and ferns of swampy forests about 250 to 350 million years ago. As they died they sank into the mud where lack of oxygen prevented decay and formed peat. Layers of sediment buried the peat; the weight and heat squeezed out water and gases and concentrated the carbon, turning it in stages into lignite (brown coal, about 30 to 40 per cent carbon), bituminous coal (60 to 80 per cent) and anthracite (over 90 per cent carbon, the hardest and best). India's coal lies mainly in Jharkhand, Odisha, Chhattisgarh, West Bengal and the Godavari valley, where the Singareni collieries of Telangana have mined it since 1889. Coal fuels about two-thirds of India's electricity, including the thermal stations at Vijayawada and Visakhapatnam, and the steel plant at Visakhapatnam uses coke made from it.

Petroleum (rock oil) formed from marine plankton and other tiny organisms that settled on the sea floor, were buried in sediment and were converted over millions of years into a mixture of hydrocarbons, which collected in porous rocks under impermeable caps. It is drilled out as crude oil and separated in refineries by fractional distillation into petroleum gas, petrol, kerosene, diesel, lubricating oil, paraffin wax and bitumen. Petroleum products run almost all transport and are the raw material of plastics, fertilisers, synthetic fibres, drugs and paints. India produces oil in Assam, Gujarat, Rajasthan and offshore at Bombay High, but imports over eighty per cent of its needs. Natural gas, mainly methane, occurs with petroleum and in separate fields; the Krishna-Godavari basin off the Andhra coast is one of India's largest gas fields, and gas is used for power, fertiliser, cooking (LPG and piped gas) and vehicles (CNG).

Why must fossil fuels be conserved? First, they are finite: at present rates of use, known reserves of oil may last only a few decades, coal a century or two. Second, burning them releases carbon dioxide, the chief cause of global warming, and sulphur dioxide and nitrogen oxides, which cause acid rain and breathing diseases; coal burning also releases fly ash and mercury. Third, their extraction destroys forests and land and their transport causes oil spills. Fourth, India's dependence on imported oil costs foreign exchange and makes prices unstable. Conservation means using them efficiently, replacing them with renewable energy wherever possible, and saving petroleum for the uses where nothing else will do.

Since fossil fuels are running out and warming the planet, the world must both use less energy and get more of it from renewable sources. India has set a target of a large share of its electricity from renewables, and Andhra Pradesh, with its sunshine, wind and coastline, is well placed.

Solar energy is the most abundant. Photovoltaic panels convert sunlight directly to electricity; solar water heaters warm water for homes and hostels; solar cookers cook with concentrated sunlight; solar pumps lift water for irrigation without diesel. Andhra Pradesh has large solar parks at Kurnool (one of the biggest in the world when built) and Anantapur. Wind energy turns turbines on the windy ridges of Anantapur, Kurnool and Chittoor, and Tamil Nadu and Gujarat lead the country. Hydroelectricity from Srisailam, Nagarjunasagar and Machkund uses falling water; small hydro on hill streams avoids the damage of big dams. Biogas from cow dung and kitchen waste in a village digester gives methane for cooking and slurry for manure, replacing fuel wood and LPG. Biomass such as rice husk and bagasse from sugar mills fuels small power plants. Tidal and wave energy and geothermal energy are possible in some places. Nuclear energy from uranium, as at Kudankulam, is non-renewable but gives large power without carbon dioxide, though it raises the problems of safety and waste.

Using less energy is as important as making it cleanly. In transport, buses, trains and shared vehicles carry many people for the fuel of one car; cycling and walking need none; electric vehicles run on grid power that can be renewable. In homes, LED bulbs use one-tenth the power of incandescent ones, five-star appliances use less, and switching off unused lights and fans costs nothing. In farming, drip irrigation reduces pumping, and solar pumps replace diesel. In industry, waste heat is recovered and efficient motors are installed. In buildings, design for daylight and ventilation reduces the need for lamps and air conditioners.

The cooking fuel of villages deserves special mention. Fuel wood gathered from forests degrades them and smoke from open fires damages the lungs of women and children. Improved smokeless stoves, biogas plants, LPG connections under government schemes and solar cookers each reduce the pressure on the forest and the smoke in the kitchen.

The goal of all this is to move from an economy that burns stored sunlight of the past to one that lives on the sunlight of the present, which is the only truly sustainable source.

Every product we buy has used resources: metal, wood, water, energy and land. Every product we throw away becomes waste that must be burnt, buried or left to litter the land. The pressure on natural resources can be cut at both ends by following five simple rules, remembered as the five Rs.

Reduce means using less in the first place: fewer things, less packaging, less water and electricity. Buy only what you need, choose durable goods over disposable ones, fix a dripping tap, switch off what is not in use, take a bath with a bucket instead of a shower, print on both sides of the paper. Reducing is the most effective R because a resource not used is a resource wholly saved.

Reuse means using an item again, for the same purpose or a different one, instead of discarding it. Glass jars become storage containers, old clothes become dusters or are passed on, a plastic bottle becomes a plant pot, the water used to wash vegetables waters the garden, envelopes are used twice, textbooks are handed down. Reuse needs no energy for reprocessing and is therefore better than recycling.

Recycle means collecting a used material and processing it into a new product. Paper is pulped again, glass is melted, aluminium cans and iron are re-smelted, some plastics are shredded and moulded, and kitchen waste is composted into manure. Recycling saves raw material and energy; recycling aluminium uses only five per cent of the energy of making it from bauxite. But recycling still needs energy and transport, and it works only when waste is separated at the source into wet (biodegradable), dry (recyclable) and hazardous (batteries, tube lights, medicines) streams, which is why municipalities ask households to use separate bins.

Recover means getting something useful from waste that cannot be reused or recycled: burning waste to generate heat or electricity in a waste-to-energy plant, capturing methane from landfill or from a biogas digester, or extracting metals from electronic waste. Recovery is the last step before disposal.

Refuse means saying no to what harms the environment: plastic carry bags, single-use cups and straws, products with excess packaging, goods made from endangered species, and anything that will become waste within a day. Refusing is the first R in importance, because it stops the problem before it starts.

The five Rs together form a hierarchy: refuse and reduce first, then reuse, then recycle, then recover, and only what is left goes to disposal. A family, a school and a town can each apply them. A school that refuses plastic, reduces paper, reuses one-sided sheets, recycles the rest and composts the canteen waste sends almost nothing to the dump and teaches the habit that its students will carry for life.

The ideas of this chapter come together in the principle of sustainable development: development that meets the needs of the present generation without reducing the ability of future generations to meet their own needs. The definition was given by the Brundtland Commission of the United Nations in 1987 and has since guided environmental policy worldwide. It does not ask us to stop using resources; it asks us to use renewable resources no faster than they renew, to use non-renewable resources sparingly and to develop substitutes for them, and to release wastes no faster than the environment can absorb them.

Applied to the resources of this chapter, sustainability means: keeping the soil covered and feeding it with organic matter so that it yields for centuries; taking ground water no faster than the monsoon recharges it and harvesting rain to increase that recharge; cutting forests no faster than they grow, and giving the people who live beside them a stake in their protection; and shifting from fossil fuels to the sun, wind and water before the fossil fuels are gone and the climate is changed beyond repair. It also means equity: the poor, the tribal, the tail-end farmer and the coming generation have as much right to resources as the rich, the city and the present.

The Indian tradition has long held this view. Gandhi's saying that the Earth provides enough for everyone's need but not for anyone's greed is the principle in one sentence. The Bishnois, the Chipko women, the tank builders of the Telugu country and the tribal custom of taking only what is needed all practised sustainability before the word existed.

What is our responsibility as students? To know, first: to understand the water cycle and the food chain well enough to see why a bore well runs dry and why pesticides return in our milk. To act in small ways every day: the five Rs, saving water and power, planting and protecting a tree, refusing plastic. To act with others: through the school Eco-club, the village watershed committee, the VSS, cleanliness drives, and by speaking up when a tank is encroached or a hill is quarried. And to make the long-term choices that add up, in what we buy, how we travel, what we grow and what we vote for.

The Earth is the only home we have. The soil, water, forests and fuels it holds were not made by us and are not ours alone; we hold them in trust from those who came before for those who come after. Using them so that the trust is kept is the whole meaning of this chapter.