Much of the world’s supply of food is produced in the northern temperate climatic zone, which includes the cleared deciduous forest lands of western Europe, the equivalent region in eastern North America and the steppes and prairies of the continental interiors. The equivalent zone in the southern hemisphere is much more restricted in area but is equally productive. The soils of the prairies and steppes usually do not need drainage works because of their location in regions where annual precipitation rarely exceeds evapotranspiration. Field drainage is an important feature of agricultural production mainly in the maritime temperate regions, the former deciduous forest lands, where annual precipitation usually exceeds evapotranspiration, sometimes by a considerable amount. This results in an excess of soil water, at least during a part of the year, and experience has shown that soil productivity can be improved by removing excess soil water. The main objective of field drainage is to maintain or improve soil productivity but, as a secondary benefit, it also improves trafficability.
KeywordsGroundwater Table Outlet Channel Perched Water Table Land Drainage Drainage Problem
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