Land, Soil and Water Resources

Three natural resources are so basic that life as we know it would be impossible without them: the land we live and build on, the soil that grows our food, and the water we drink and farm with. All three are under growing pressure. Understanding them, and how to conserve them, is vital.

A resource is anything in our environment that can be used to satisfy a human need. The key idea is utility, or usefulness. A thing becomes a resource only when people can use it. Coal lay underground for millions of years. It became a resource only when people learned to burn it for energy. To count as a resource, a thing must also be technologically accessible, economically feasible and culturally acceptable.

Resources do not exist on their own. Human knowledge, skill and technology turn things into resources. As our abilities grow, new resources are created.

Resources are classified in four useful ways.

• By origin: biotic resources come from living things (plants, animals, fossil fuels). Abiotic resources come from non-living things (rocks, metals, water).
• By exhaustibility: renewable resources can be renewed or reproduced (solar energy, wind, water, forests). Non-renewable resources take millions of years to form and can run out (coal, petroleum, minerals).
• By ownership: resources may be individual, community, national or international. The oceans beyond 200 nautical miles of a coast are an international resource.
• By stage of development: potential resources are known but not yet used, such as the solar and wind energy of Rajasthan. Developed resources are surveyed and in use. Stock is material we cannot yet use for lack of technology. Reserves are the part of the stock we could use in future.

A broader grouping separates natural resources (from nature), human-made resources (things people create, like buildings, machines, roads and bridges) and human resources (people themselves: their numbers, skills, knowledge and health, which let them use all other resources).

Resources are not spread evenly. Some regions are rich in minerals but short of water. Others have fertile land but few minerals. Resource planning means using resources carefully so they are not wasted or exhausted, and so their benefits reach everyone. Thoughtless use brings two dangers: the exhaustion of resources at the hands of a few, and pollution. India has planned its resources from the time of its first Five Year Plans, the centralised development plans begun after independence. Having resources is not enough. A region also needs technology, skill and institutions to turn them into development. That is why some resource-rich regions have stayed poor while resource-poor ones have prospered.

Conservation means using resources carefully and wisely so they are not wasted or exhausted. It includes:

• Economy in use: using resources sparingly and avoiding waste.
• Renewal time: giving renewable resources time to renew themselves.
• Reuse and recycling: getting more use out of what is already extracted.
• Substitutes: finding replacements for scarce resources.

Conservation supports sustainable development: meeting present needs without robbing future generations. Resources belong not only to us but to those who come after.

Land is a fundamental natural resource. We use it in many ways: for agriculture, forests, grazing, building houses, roads and industry. But only a part of the Earth's land is habitable. Deserts, high mountains and ice cover much of it.

How land is used (land use) is shaped by:

• relief (flat plains are good for farming and cities),
• climate and soil,
• and population and technology.

Because land is limited and demand keeps rising, careful land-use planning matters.

In India, land is put to several recorded uses: forests, the net sown area (land actually under crops), pasture, land under tree crops, and waste land such as rocky or desert tracts, along with non-farm uses like buildings and roads. A healthy country is expected to keep about one-third of its area under forest. India's forest cover is well below that target. This is a matter of environmental concern.

Soil is the thin top layer of the Earth in which plants grow. It is precious because it takes a very long time to form. It weathers slowly from rock over thousands of years. All our food ultimately depends on soil.

Soil is threatened by degradation, especially erosion (washing or blowing away of topsoil), as well as overuse and pollution. Erosion is caused by running water, wind, and human actions such as deforestation and over-grazing.

Erosion by water does not begin with dramatic ravines. It advances through stages, each more severe than the last.

• Splash erosion: the first stage. Raindrops strike bare soil and knock particles loose.
• Sheet erosion: flowing water then removes a thin, even layer of topsoil from the whole surface.
• Rill erosion: the flow concentrates and cuts small, shallow channels called rills.
• Gully erosion: the rills deepen and widen into gullies, deep channels that ruin farmland into what is known as bad land.

So the correct order is splash, then sheet, then rill, then gully. Soil can be conserved by:

• afforestation (planting trees) and maintaining plant cover,
• terracing slopes and contour ploughing (ploughing along the contour lines of a slope) to slow run-off,
• strip cropping (growing crops in strips to break the force of the wind),
• shelter belts (rows of trees planted to hold the soil against the wind),
• crop rotation and avoiding overgrazing.

Protecting soil is protecting our ability to feed ourselves.

India's soils differ from region to region because the parent rock, climate and drainage differ. Knowing which rock a soil weathers from, and which minerals give it its colour, explains where each soil occurs and what grows on it.

• Alluvial soil: deposited by rivers across the Northern Plains and coastal deltas. It is the most widespread and most fertile soil in India, renewed by floods, and it supports wheat, rice and sugarcane.
• Black soil (regur): formed by the weathering of fissure volcanic rock, the basaltic lava of the Deccan Trap that erupted through cracks in the crust. It is dark, clayey and moisture-retentive, and it is ideal for cotton, which is why it is called black cotton soil.
• Red soil: also described as red and yellow soil, it develops on crystalline and metamorphic rocks (granite and gneiss) in the low-rainfall southern and eastern peninsula. Its red colour comes from ferric oxides, iron compounds left behind by weathering under good drainage. It is generally poor in nitrogen, phosphorus and humus.
• Laterite soil: forms in hot, humid regions with heavy rainfall, where intense leaching washes away the soluble nutrients. It is red because of its iron content but deficient in nitrogen and potash. It occurs in the humid parts of the peninsula, such as Kerala, Karnataka and the Western Ghats, not in dry Rajasthan or Uttar Pradesh. With manuring it supports tapioca and cashew nut, and it also grows tea and coffee.
• Desert (arid) soil: sandy and saline, found in Rajasthan and other low-rainfall areas. It is low in humus and needs irrigation to be productive.
• Forest soil: found in the hilly and mountain areas.

A useful distinction for exams: red soil and laterite soil are both reddish from iron, but red soil is a product of weathered crystalline rock, while laterite is a product of leaching under heavy tropical rain. Black soil alone traces back to volcanic lava.

Water covers most of the planet. Yet fresh water (the kind we can drink and use) is scarce. It is only a tiny fraction of the total. With growing populations, farming and industry, many regions face water shortages.

Even the small freshwater fraction is mostly out of reach. Most of it is locked in ice caps and glaciers, frozen in the polar regions and high mountains. Of what remains, groundwater is by far the largest share. It accounts for about 30 per cent of all fresh water, far more than all lakes, rivers, atmospheric moisture and soil moisture put together. Rivers and lakes, the sources we see, hold only a small portion. This is why groundwater, and the water table (the level below which the ground is saturated with water), matter so much.

Riverbed sand is not inert material. The sand layer of a riverbed acts as an aquifer, a natural filter and store that lets river water seep down and recharge groundwater. Heavy sand mining strips this layer away. Two consequences follow.

• Pollution of groundwater: with the filtering sand gone, pollutants in the river enter the groundwater directly.
• A lower water table: the riverbed deepens and recharge falls, so the water table in nearby areas drops and wells run dry.

Note what sand mining does not do: it does not make the groundwater saline. Salinity comes from other causes, such as seawater intrusion or arid-zone evaporation, not from the removal of sand.

Conserving water is therefore urgent. Methods include:

• rainwater harvesting (collecting and storing rain),
• efficient irrigation (like drip irrigation),
• preventing pollution of rivers and lakes, and
• avoiding waste in homes and farms.

Land, soil and water are interlinked. Healthy soil holds water, and good land use protects both. Caring for all three together is essential for a sustainable future.