Water resources Water can be considered a
renewable material when carefully controlled usage and temperature, treatment, and release are followed. If not, it would become a non-renewable resource at that location. For example, as
groundwater is usually removed from an
aquifer at a rate much greater than its very slow natural recharge, it is a considered non-renewable resource. Removal of water from the pore spaces in aquifers may cause permanent compaction (
subsidence) that cannot be renewed. 97.5% of the water on the Earth is salt water, and 3% is
fresh water; slightly over two thirds of this is frozen in
glaciers and
polar ice caps. The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction (0.008%) present above ground or in the air.
Water pollution is one of the main concerns regarding water resources. It is estimated that 22% of worldwide water is used in industry. Major industrial users include hydroelectric dams,
thermoelectric power plants (which use water for cooling),
ore and
oil refineries (which use water in chemical processes) and manufacturing plants (which use water as a solvent), it is also used for dumping garbage.
Desalination of seawater is considered a renewable source of water, although reducing its dependence on fossil fuel energy is needed for it to be fully renewable. File:Sinclair Wetlands.jpg|
Panorama of a natural wetland (Sinclair Wetlands, New Zealand) Non agricultural food - renewable resources Food is any substance consumed to provide nutritional support for the body. Most food has its origin in renewable resources. Food is obtained directly from plants and animals. Hunting may not be the first source of meat in the modernised world, but it is still an important and essential source for many rural and remote groups. It is also the sole source of feeding for wild carnivores.
Sustainable agriculture The phrase
sustainable agriculture was coined by Australian agricultural scientist
Gordon McClymont. It has been defined as "an integrated system of plant and animal production practices having a site-specific application that will last over the long term". Expansion of agricultural land reduces
biodiversity and contributes to
deforestation. The
Food and Agriculture Organization of the United Nations estimates that in coming decades, cropland will continue to be lost to industrial and urban development, along with reclamation of wetlands, and conversion of forest to cultivation, resulting in the
loss of biodiversity and increased
soil erosion. Although
air and
sunlight are available everywhere on
Earth,
crops also depend on
soil nutrients and the availability of
water.
Monoculture is a method of growing only one crop at a time in a given field, which can damage land and cause it to become either unusable or suffer from reduced
yields. Monoculture can also cause the build-up of
pathogens and pests that target one specific species. The
Great Irish Famine (1845–1849) is a well-known example of the dangers of monoculture.
Crop rotation and
long-term crop rotations confer the replenishment of nitrogen through the use of
green manure in sequence with cereals and other crops, and can improve
soil structure and
fertility by alternating deep-rooted and shallow-rooted plants. Other methods to combat lost soil nutrients are returning to natural cycles that annually flood cultivated lands (returning lost nutrients indefinitely) such as the
Flooding of the Nile, the long-term use of
biochar, and use of crop and livestock
landraces that are adapted to less than ideal conditions such as pests, drought, or lack of nutrients. Agricultural practices are one of the single greatest contributor to the global increase in
soil erosion rates. It is estimated that "more than a thousand million tonnes of southern Africa's soil are eroded every year. Experts predict that crop yields will be halved within thirty to fifty years if erosion continues at present rates." The
Dust Bowl phenomenon in the 1930s was caused by severe
drought combined with farming methods that did not include crop rotation, fallow fields,
cover crops, soil terracing and wind-breaking trees to prevent
wind erosion. The
tillage of agricultural lands is one of the primary contributing factors to erosion, due to mechanised agricultural equipment that allows for deep plowing, which severely increases the amount of soil that is available for transport by
water erosion. The phenomenon called
peak soil describes how large-scale factory farming techniques are affecting humanity's ability to grow food in the future. Without efforts to improve
soil management practices, the availability of
arable soil may become increasingly problematic. , 2010 Methods to combat erosion include
no-till farming, using a
keyline design, growing
wind breaks to hold the soil, and widespread use of
compost.
Fertilizers and
pesticides can also have an effect of soil erosion, which can contribute to
soil salinity and prevent other species from growing.
Phosphate is a primary component in the chemical fertiliser applied most commonly in modern agricultural production. However, scientists estimate that rock phosphate reserves will be depleted in 50–100 years and that
Peak Phosphate will occur in about 2030.
Industrial processing and
logistics also have an effect on agriculture's sustainability. The way and locations crops are
sold requires energy for transportation, as well as the energy cost for materials,
labour, and
transport. Food sold at a local location, such a
farmers' market, have reduced energy overheads.
Air Air is a renewable resource. All
living organisms need
oxygen,
nitrogen (directly or indirectly),
carbon (directly or indirectly) and many other gases in small
quantities for their
survival. ==Non-food resources==