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Some of the environmental and ecological problems that emerged out of cultivation of the high yielding varieties are depletion of forests ,reduction in pastures ,salination ,water-logging ,depletion of underground water table ,soil erosion ,change in the soil chemistry ,emergence of new plant diseases ,and health hazards.
SALINATION -The high yielding varieties of rice and wheat require several waterings ,especially in the area where the average annual rainfall is about 65cm.The problem of salinity and alkalinity can be solved by use of manure(cowdung, compost ,green manure ,)and by a judicious selection of leguminous crop in the rotation .Cultivation of salt tolerant crops like barley ,sugar beet, salt grass ,asparagus ,spinach, and tomato may also help to a great extent and may improve the fertility of such lands.
2.WATER LOGGING- Water logging is the other major problem associated with over-irrigation .An agricultural land is said to be water logged when its productivity gets affected by the high ground water table. The productivity of the land is affected when the root zone of plant gets flooded with water and becomes ill-aerated. Because of the inadequate aeration of the root zone, oxygen required by the plant to maintain its growth is reduced and thus yield of the crop is reduced.
3.SOIL EROSION-It is a universal phenomena. The presence of forests reduces the danger of soil erosion significantly .In recent years ,the Agricultural area has been expanded by indiscriminate felling of trees .The increase in the rate of soil erosion is not only damaging the agricultural lands ,it is also affecting adversely the areas where the eroded soil is deposited .Development of terraces in the hills ,leveling of gullies and contour ploughing in the hilly area can also go a long way in reducing soil erosion.is the upper-most layer of the ground, is moved from one spot to another. soil erosion is a naturally occurring and slow process that refers to the loss of the field’s topsoil by water and wind or through the conversion of natural vegetation to agricultural land.
Detachment: This is when the topsoil is actually “detached” from the rest of the ground
Movement: This is when the topsoil is relocated to another area
Deposition: Where the topsoil ends up after this process.
4.POLLUTION-The high yielding varieties perform better if heavy doses of chemical fertiliser ,insecticides ,and pesticides are applied . Application of heavy doses ,of these inputs destroy the micro organisms which are so necessary to maintain the fertility of the soil .The toxic chemicals present in the soil can decrease soil fertility and therefore decrease in the soil yield. The contaminated soil is then used to produce fruits and vegetables, which lacks quality nutrients and may contain some poisonous substance to cause serious health problems in people consuming them.
