Leaching (agriculture)
Encyclopedia
In agriculture
, leaching refers to (1) the loss of water-soluble plant nutrient
s from the soil
, due to rain
and irrigation
. Soil structure
, crop planting, type and application rates of fertilizer
s, and other factors are taken into account to avoid excessive nutrient loss.
Leaching may also refer to (2) the practice of applying a small amount of excess irrigation
where the water has a high salt content to avoid salts from building up in the soil
(salinity control
). Where this is practiced, drainage
must also usually be employed, to carry away the excess water.
Leaching is an environmental
concern when it contributes to groundwater
contamination
. As water from rain, flooding, or other sources seeps into the ground, it can dissolve chemicals and carry them into the underground water supply. Of particular concern are hazardous waste
dumps and landfill
s, and, in agriculture, excess fertilizer, improperly stored animal manure, and biocides (e.g. pesticides, fungicides, insecticides and herbicides).
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
, leaching refers to (1) the loss of water-soluble plant nutrient
Nutrient
A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...
s from the soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
, due to rain
Rain
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...
and irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...
. Soil structure
Soil structure
Soil structure is determined by how individual soil granules clump or bind together and aggregate, and therefore, the arrangement of soil pores between them...
, crop planting, type and application rates of fertilizer
Fertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...
s, and other factors are taken into account to avoid excessive nutrient loss.
Leaching may also refer to (2) the practice of applying a small amount of excess irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...
where the water has a high salt content to avoid salts from building up in the soil
Soil salination
Soil salinity is the salt content in the soil.- Causes of soil salinity :Salt-affected soils are caused by excess accumulation of salts, typically most pronounced at the soil surface. Salts can be transported to the soil surface by capillary transport from a salt laden water table and then...
(salinity control
Salinity control
Soil salinity control relates to controlling the problem of soil salinity and reclaiming salinized agricultural land.The aim of soil salinity control is to prevent soil degradation by salinization and reclaim already salty soils...
). Where this is practiced, drainage
Drainage
Drainage is the natural or artificial removal of surface and sub-surface water from an area. Many agricultural soils need drainage to improve production or to manage water supplies.-Early history:...
must also usually be employed, to carry away the excess water.
Leaching is an environmental
Natural environment
The natural environment encompasses all living and non-living things occurring naturally on Earth or some region thereof. It is an environment that encompasses the interaction of all living species....
concern when it contributes to groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
contamination
Contamination
Contamination is the presence of a minor and unwanted constituent in material, physical body, natural environment, at a workplace, etc.-Specifics:"Contamination" also has more specific meanings in science:...
. As water from rain, flooding, or other sources seeps into the ground, it can dissolve chemicals and carry them into the underground water supply. Of particular concern are hazardous waste
Hazardous waste
A hazardous waste is waste that poses substantial or potential threats to public health or the environment. According to the U.S. environmental laws hazardous wastes fall into two major categories: characteristic wastes and listed wastes.Characteristic hazardous wastes are materials that are known...
dumps and landfill
Landfill
A landfill site , is a site for the disposal of waste materials by burial and is the oldest form of waste treatment...
s, and, in agriculture, excess fertilizer, improperly stored animal manure, and biocides (e.g. pesticides, fungicides, insecticides and herbicides).
See also
- Leaching (pedology)Leaching (pedology)In pedology, leaching is the loss of mineral and organic solutes due to percolation. It is a mechanism of soil formation. It is distinct from the soil forming process of eluviation, which is the loss of mineral and organic colloids. Leached and elluviated materials tend to be lost from topsoil and...
- Leaching model (soil)
- Soil salinity control (leaching requirement, leaching efficiency)
- SaltModSaltModSaltMod is computer program for the prediction of the salinity of soil moisture, groundwater and drainage water, the depth of the watertable, and the drain discharge in irrigated agricultural lands, using different hydrologic conditions, varying water management options, including the use of...
(agro-hydro-salinity and leaching model) - SahysModSahysModSahysMod is a computer program for the prediction of the salinity of soil moisture, groundwater and drainage water, the depth of the watertable, and the drain discharge in irrigated agricultural lands, using different hydrogeologic and aquifer conditions, varying water management options, including...
(spatial agro-hydro salinity, leaching and groundwater model)
External links
- R.J.Oosterbaan, Water and salt balances in agricultural hydrology. Lecture notes, International Course on Land Drainage, ILRI, Wageningen, The Netherlands. On line : http://www.waterlog.info/pdf/balances.pdf
- R.J.Oosterbaan, 1997. "SaltMod: A tool for interweaving of irrigation and drainage for salinity control". In: W.B.Snellen (ed.), Towards integration of irrigation, and drainage management. ILRI Special report, p. 41-43. On line : http://www..waterlog.info/pdf/toolsalt.pdf