Natural Resources in an Agricultural Context

Conservation

Conservation is the sustainable use of natural resources, such as soils, water, plants, animals, and minerals. In economic terms, the natural resources of any area constitute its basic capital and wasteful use of those resources constitutes an economic loss. From the aesthetic and moral viewpoint, conservation also includes the maintenance of national parks, wilderness areas, historic sites and wildlife. In certain cases, conservation may imply the protection of a natural environment from any human economic activity. Natural resources are of two main types, renewable and non-renewable. Renewable resources include wildlife and natural vegetation of all kinds. The soil itself can be considered a renewable resource, although severe damage is difficult to repair because of the slow rate of soil-forming processes. The natural drainage of waters from the watershed of a region can be maintained indefinitely by careful management of vegetation and soils, and the quality of water can be controlled through pollution control. (See Air Pollution, Environment, Reclamation, Sewage Disposal, Water Pollution and Energy Conservation:) Non-renewable resources are those that cannot be replaced or that can be replaced only over extremely long periods of time. Such resources include fossil fuels (coal, petroleum, and natural gas) and metallic and other ores. For discussions of conservation problems in this area, see individual entries on the substances concerned.

History

Although the conservation of natural resources has been recognised as desirable by many peoples since ancient times, frequently the basic principles of sound land use have been ignored with disastrous results. Major losses, for example, the silting of rivers and the flooding of lowlands, resulted from the destruction of the forests and grasslands that protected watersheds in northern China and the Tigris-Euphrates area.

Large areas in North Africa and the Middle East were rendered barren by centuries of uncontrolled livestock grazing, unwise cultivation, and excessive cutting of woody plants for fuel. Similar damage has also occurred in most of the more recently developed regions of the world, sometimes through the unwise introduction of species into new environments. The increasing industrialisation of nations around the world continues to present severe conservation problems although international cooperation efforts have also evolved in certain areas, such as the protection of some endangered species. Some basic conservation principles in major areas of concern are discussed below.

Conservation of Grazing Lands

One of the principles of range conservation is the use of only a portion (usually about a half) of the annual forage-plant production of a particular range in order to maintain healthy plant growth and reproduction. In addition, each range is stocked with the number of animals that can be nourished properly on the available usable forage and are permitted to graze only during the season suitable for that type of range. The conservation of ranges is based on a programme of grazing designed to keep them productive indefinitely and to improve depleted areas by natural reproduction or by artificial seeding with appropriate forage species. Although these principles are well established, many hundreds of thousands of acres of public grazing lands are still overgrazed.

Wildlife Conservation

One of the basic principles of wildlife conservation involves providing adequate natural food and shelter to maintain the populations of each species in a given habitat. A major threat facing wildlife is both the destruction of habitat, through drainage, agriculture and urban expansion, and the fragmentation of habitat into parcels too small for wildlife populations to use. Illegal trade in feathers, horns, ivory, hides, and organs has brought many endangered species to the verge of extinction. Wildlife is an important biological, economic, and recreational resource that can be maintained through careful management. Hunting regulations allow the culling of many species without affecting overall population levels, and can even help control species that have grown too abundant for the region they inhabit.

Soil Conservation

In order to preserve their farmlands, many farmers use the strip cropping method as seen here. By alternating strips of cultivated crops with strips of sod-forming crops, the farmer can relieve the effects of erosion. (Soil Conservation Service)

Among the basic measures for soil conservation currently in use is the zoning of land by capability classes. In this system, the more level and stable soils are designated as suitable for annual crops, and other areas are designated for perennials, such as grass and legumes, or for use as grazing or forest lands.

Another conservation method involves the use of soil-building plants in crop rotations. Such crops hold and protect the soil during growth and when ploughed under, supply much-needed organic matter to the soil.

Cultivation methods that leave a layer of vegetable waste on the surface of the soil represent a major advance in land use. In many areas, these techniques have supplanted the use of the mouldboard plough, associated with the practice known as clean cultivation, which left the soil surface exposed to all the natural erosive forces.

Special methods for erosion control include contour farming, in which cultivation follows the contours of sloping lands, ditches and terraces are constructed to diminish the run-off of water. Another soil-conservation method is the use of strip-cropping—that is, alternating strips of crop and fallow land. This method is valuable for the control of wind erosion on semi-arid lands that need to lie fallow for efficient crop production. In addition, the maintenance of soil fertility at the maximum level of production often involves the use of inorganic (chemical) fertilisers.

Renewable Energy

Renewable Energy is energy present in the natural flows of wind, water, and sunlight in the environment and that is continually replenished as quickly as it is extracted and used. Renewable energy will therefore never run out.

The Importance of Renewable Energy

Most of the energy sources on Earth originate from the Sun, with the exceptions of the energy in the tides, caused by the gravitational pull of the Moon and Sun, and geothermal energy, which results from the heat escaping from hot rocks 2 km (1.2 mi) below the Earth’s surface and from the effects of radioactive decay. The Sun's radiation is equivalent to 1.4 kW/sq mi in space before any attenuation due to travelling through the Earth’s atmosphere. This solar radiation is converted naturally into various energy streams. Wave energy results from the interaction between the convection-driven winds and the surface of the sea; hydro-energy is produced by the hydrological cycle; and biological energy (biomass energy) is that which is stored in living organisms by the process of photosynthesis. All these forms of energy are available as renewable resources because of the continual replacement of the energy on a daily, or even hourly, basis. By way of contrast, fossil fuels such as coal, oil, and gas, although originally laid down effectively as biomass, take millions of years to form and need to be regarded as finite, non-renewable resources.

The Fundamental Energy

Resource the sun. Solar energy strikes the surface of the Earth at the rate of 120,000 TW (Terawatts; 1 TW equals 1012 Watts) or 10,000 times the current global energy demand. Although a large proportion of this energy is radiated back into space, approximately one-third of this energy is converted by the hydrological cycle into heat, a smaller proportion into wind and waves, and about 30 TW is converted into biomass.