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Many agricultural soils need drainage to improve production or to manage water supplies. 1 Reasons for artificial drainage
Wetland soils may need drainage to be used for agriculture in the first place. In northern USA and Europe, glaciation created numerous small lakes which gradually filled with humus to make marshes. Some of these were drained to make mucklands, which are primarily used for high value crops such as vegetables. Drainage must be maintained on these, not only to prevent flooding, but to also keep the soil moist enough to prevent wind erosion and fires.
The largest project of this type in the world has been in process for centuries in the Netherlands. The area between Amsterdam, HaarlemHaarlem is a city in the west of the Netherlands, capital of the North Holland province. The city is located by the river Spaarne, about 20 km west of Amsterdam and near the coastal dunes. It is the center of a flower-growing district and the export point and LeidenLeiden (in English also, but now rarely, Leyden is a city and municipality in South Holland, The Netherlands. It forms one urban area with Oegstgeest, Leiderdorp and Voorschoten. It is located on the Old Rhine, close to the cities of The Hague and Haarlem was, in prehistoric times mucky swampland and small lakes. PeatLewis, Scotland Peat is an accumulation of partially decayed vegetable matter. Peat forms in wetlands or peatlands variously called bogs moors muskegs mires and fens''. Geographic distribution Peat deposits are found in many places around the world, notab miningSilver City, New Mexico is an open-pit copper mine Mining is the extraction of valuable minerals or other geological materials from the earth, usually (but not always) from an ore body, vein or (coal) seam. Materials commonly recovered by mining include b, subsidenceSubsidence is a term used in geology, engineering and surveying to denote the motion of a surface (usually, the earth's surface) downwards relative to a datum such as sea-level. In meteorology, subsidence refers to the movement of air downwards. Surfaces and shoreline erosion gradually caused the formation of one large lake, the Haarlemmermeer, or lake of Haarlem. The invention of windFor the 1928 film, see The Wind. Wind in the most general sense, is the movement of air. It occurs at all scales, from local breezes generated by heating of land surfaces and lasting tens of minutes to global winds resulting from solar heating of the plan powered pumpA pump is a mechanical device used to move liquids or gases. Also the heart is an essential pump in humans and animals to move the blood around. The earliest pump was described by Archimedes around 300 BC and is known as the Archimedes screw pump. Pumps wing stations in the 15th century permitted drainage of some of the surrounding land, but the drainage of the entire lake awaited until the design of large steam powered pumps and agreements between regional authorities. The elimination of the lake occurred between 1849 and 1852, creating thousands of acres (many square km) of new land. See Haarlemmermeer for the history of the drainage.
Coastal plains and river deltas may have seasonal or permanent high water tables and must have drainage improvements to be used for agricultural purposes. An example is the flatwoods citrus-growing region of Florida. After periods of high rainfall, drainage pumps are employed to prevent damage to the citrus groves from overly wet soils. Rice production requires complete control of water, as fields may be flooded or drained at different stages of the crop cycle. The Netherlands has also led the way in this type of drainage, not only to drain lowland along the shore, but actually pushing back the sea until the original nation has been greatly enlarged.
Moist climate soils may be adequate for cropping with the exception that they become waterlog ged for brief periods each year, from snow melt or from heavy rains. Soils that are predominantly clay will pass water very slowly downward, meanwhile plant roots suffocate because the excessive water around the roots eliminates air movement through the soil.
Other soils may have an impervious layer of mineralized soil, called a hardpan or relatively impervious rock layers may underlie shallow soils. Drainage is especially important in tree fruit production. Soils that are otherwise excellent may be waterlogged for a week of the year, which is sufficient to kill fruit trees and cost the productivity of the land until replacements can be established. In each of these cases appropriate drainage is used to carry off temporary flushes of water to prevent damage to annual or perennial crops.
In farming drier areas, irrigation is often used, and one would not consider drainage necessary. However, irrigation water always contains minerals, and these minerals can be concentrated to toxic levels by evapotranspiration. Irrigated land may need periodic flushes with excessive irrigation water and drainage to remove these toxic minerals.
