Soil erosion and its prevention:
Soil erosion by water, wind and tillage affects both agriculture and the natural environment. Soil loss, and its associated impacts, is one of the most important (yet probably the least well-known) of today's environmental problems. It is mostly due to poor land use practices, which include deforestation, overgrazing, unmanaged construction activity and road or trail building.
Soil is a complex mixture of living and non-living materials. It provides anchorage and sustenance to plants. Natural agents like water and wind, constantly tend to remove the top soil and cause erosion. Rain falling upon the unprotected top soil, washes it down into the streams. Due to the absence of plant covering, eroded soil cannot hold water. Water rushes into the rivers and overflows as flood. Dust storm also causes soil erosion. The particles of top soil are picked up in such quantities that they form clouds of dust. Human beings also cause soil erosion. The growing human habitation and expansion of urban areas lead to removal of vegetation. Once vegetation is removed, the naked soil gets exposed to wind and water. Improper tillage is another cause of soil erosion. Farmers often loosen the top soil for removing weeds and preparing seed beds. They also leave agricultural fields lying fallow for long time. These practices expose the top soil to the wind and cause erosion.
Soil erosion is always a result of mankind's unwise actions, such as overgrazing or unsuitable cultivation practices. These leave the land unprotected and vulnerable. Accelerated soil erosion by water or wind may affect both agricultural areas and the natural environment, and is one of the most widespread of today's environmental problems. Soil erosion is just one form of soil degradation. Other kinds of soil degradation include salinisation, nutrient loss, and compaction.
Prevention of soil erosion: Plants provide protective cover on the land and prevent soil erosion for the reasons: (a) plants slow down water as it flows over the land (runoff) and this allows much of the rain to soak into the ground; (b) plant roots hold the soil in position and prevent it from being washed away; (c) plants break the impact of a raindrop before it hits the soil, thus reducing its ability to erode; (d) plants in wetlands and on the banks of rivers are of particular importance as they slow down the flow of the water and their roots bind the soil, thus preventing erosion.
Preventing soil erosion requires technical changes to adopt. Aspects of technical changes include: (i) use of contour ploughing and wind breaks; (ii) leaving unploughed grass strips between ploughed land; (iii) making sure that there are always plants growing on the soil, and that the soil is rich in humus (decaying plant and animal remains). This organic matter is the "glue" that binds the soil particles together and plays an important part in preventing erosion; (iv) avoiding overgrazing and the over-use of crop lands; (v) allowing indigenous plants to grow along the river banks instead of ploughing and planting crops right up to the water's edge; (vi) encouraging biological diversity by planting several different types of plants together; (vii) conservation of wetlands (see Enviro Facts "Wetlands" and "River Catchments").
We can check soil erosion by adopting the following additional practices:
1. Intensive cropping and use of proper drainage canals.
2. Terracing on the sloping fields. This retards the speed of the flowing water.
3. Planting trees and sowing grasses.
4. Extensive aforestation practices to be carried out.