Soil conservation is the prevention of loss of the topmost layer of thesoil fromerosion or prevention of reduced fertility caused by over usage,acidification,salinization or other chemicalsoil contamination.
Slash-and-burn and otherunsustainable methods ofsubsistence farming are practiced in some lesser developed areas. A consequence ofdeforestation is typically large-scaleerosion, loss of soil nutrients and sometimes totaldesertification. Techniques for improved soil conservation includecrop rotation,cover crops,conservation tillage and plantedwindbreaks, affect botherosion andfertility. When plants die, they decay and become part of the soil. Code 330 defines standard methods recommended by the U.S.Natural Resources Conservation Service. Farmers have practiced soil conservation for millennia. In Europe, policies such as theCommon Agricultural Policy are targeting the application of best management practices such as reducedtillage, winter cover crops,[1] plant residues and grass margins in order to better address soil conservation.Political and economic action is further required to solve the erosion problem. A simplegovernancehurdle concerns how we value the land and this can be changed by cultural adaptation.[2]Soil carbon is acarbon sink, playing a role inclimate change mitigation.[3]
Contour ploughing orients furrows following thecontour lines of the farmed area. Furrows move left and right to maintain a constant altitude, which reducesrunoff. Contour plowing was practiced by the ancientPhoenicians for slopes between two and ten percent.[4] Contour plowing can increase crop yields from 10 to 50 percent, partially as a result of greater soil retention.[5]
Terracing is the practice of creating nearly level areas in a hillside area. The terraces form a series of steps each at a higher level than the previous. Terraces are protected from erosion by other soil barriers. Terraced farming is more common on small farms. This involves creating a series of flat terraced levels on a sloping field.
Keyline design is the enhancement of contour farming, where the total watershed properties are taken into account in forming thecontour lines.
Trees,shrubs andground-cover are effective perimeter treatment forsoil erosion prevention, by impeding surface flows. A special form of this perimeter or inter-row treatment is the use of a "grass way" that bothchannels and dissipates runoff through surface friction, impedingsurface runoff and encouraging infiltration of the slowed surface water.[6]
Windbreaks are sufficiently dense rows oftrees at thewindward exposure of an agricultural field subject towinderosion.[7]Evergreenspecies provide year-round protection; however, as long asfoliage is present in the seasons of baresoil surfaces, the effect ofdeciduous trees may be adequate.
Cover crops such asnitrogen-fixinglegumes, white turnips, radishes and other species are rotated with cash crops to blanket the soil year-round and act asgreen manure that replenishes nitrogen and other critical nutrients. Cover crops also help to suppress weeds.[8]
Soil-conservation farming involvesno-till farming, "green manures" and other soil-enhancing practices which make it hard for the soils to be equalized. Such farming methods attempt to mimic the biology ofbarren lands. They can revive damaged soil, minimize erosion, encourage plant growth, eliminate the use of nitrogen fertilizer or fungicide, produce above-average yields and protect crops during droughts or flooding. The result is less labor and lower costs that increase farmers’ profits. No-till farming and cover crops act as sinks for nitrogen and other nutrients. This increases the amount ofsoil organic matter.[8]
Repeated plowing/tilling degrades soil, killing its beneficial fungi and earthworms. Once damaged, soil may take multiple seasons to fully recover, even in optimal circumstances.[8]
Critics argue that no-till and related methods are impractical and too expensive for many growers, partly because it requires new equipment. They cite advantages for conventional tilling depending on the geography, crops and soil conditions. Some farmers have contended that no-till complicates pest control, delays planting and that post-harvest residues, especially for corn, are hard to manage.[8]
The use ofpesticides can contaminate the soil, and nearby vegetation and water sources for a long time. They affectsoil structure and (biotic and abiotic) composition.[9][10] Differentiated taxation schemes are among the options investigated in the academic literature to reducing their use.[11]
Alternatives to pesticides are available and include methods of cultivation, use ofbiological pest controls (such as pheromones and microbial pesticides),genetic engineering (mostlyof crops), and methods of interfering with insect breeding.[12] Application of composted yard waste has also been used as a way of controlling pests.[13]
These methods are becoming increasingly popular and often are safer than traditional chemical pesticides. In addition, EPA is registering reduced-risk pesticides in increasing numbers.[citation needed]
Salinity in soil is caused by irrigating with salty water. Water then evaporates from the soil leaving the salt behind. Salt breaks down the soil structure, causing infertility and reduced growth.[citation needed][14]
Theions responsible for salination are:sodium (Na+),potassium (K+),calcium (Ca2+),magnesium (Mg2+) andchlorine (Cl−). Salinity is estimated to affect about one third of the earth'sarable land.[15] Soil salinity adversely affects cropmetabolism and erosion usually follows.
Salinity occurs ondrylands from overirrigation and in areas with shallow saline water tables. Over-irrigation deposits salts in upper soil layers as a byproduct of soilinfiltration; irrigation merely increases the rate of salt deposition. The best-known case of shallowsaline water tablecapillary action occurred inEgypt after the 1970 construction of theAswan Dam. The change in thegroundwater level led to high salt concentrations in the water table. The continuous high level of thewater table led tosoil salination.
Use ofhumic acids may prevent excess salination, especially given excessive irrigation.[16] Humic acids can fix bothanions andcations and eliminate them fromroot zones.[citation needed]
Planting species that can tolerate saline conditions can be used to lower water tables and thus reduce the rate of capillary and evaporative enrichment of surface salts. Salt-tolerant plants includesaltbush, a plant found in much ofNorth America and in theMediterranean regions ofEurope.
When worms excretefeces in the form ofcasts, a balanced selection of minerals and plant nutrients is made into a form accessible forroot uptake.Earthworm casts are five times richer in availablenitrogen, seven times richer in availablephosphates and eleven times richer in availablepotash than the surrounding upper 150 millimetres (5.9 in) of soil. The weight of casts produced may be greater than 4.5 kg per worm per year. By burrowing, the earthworm improves soilporosity, creating channels that enhance the processes of aeration and drainage.[17]
Other important soil organisms includenematodes,mycorrhiza andbacteria. A quarter of all the animal species live underground. According to the 2020Food and Agriculture Organization’s report "State of knowledge ofsoil biodiversity – Status, challenges and potentialities", there are major gaps in knowledge about biodiversity in soils.[18][19]
Degraded soil requiressynthetic fertilizer to produce high yields. Lacking structure increases erosion and carries nitrogen and other pollutants into rivers and streams.[8]
Each one percent increase in soil organic matter helps soil hold 20,000 gallons more water per acre.[8]
To allow plants to fully realize theirphytonutrient potential, activemineralization of the soil is sometimes undertaken. This can involve adding crushed rock or chemical soil supplements. In either case, the purpose is tocombatmineral depletion. A broad range of minerals can be used, including common substances such asphosphorus and more exotic substances such aszinc andselenium. Extensive research examines the phase transitions of minerals in soil with aqueous contact.[20]
Flooding can bring significantsediments to analluvial plain. While this effect may not be desirable if floods endanger life or if the sediment originates from productive land, this process of addition to afloodplain is a natural process that can rejuvenate soil chemistry through mineralization.[citation needed]
{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link){{cite book}}:|website= ignored (help)CS1 maint: multiple names: authors list (link)| Air |
| ||||||
|---|---|---|---|---|---|---|---|
| Energy | |||||||
| Land | |||||||
| Life | |||||||
| Water |
| ||||||
| Related |
| ||||||
| International | |
|---|---|
| National | |
| Other | |
