Essay - Soil Conservation

Q. Discuss the effective methods of soil conservation

Soil is almost an invaluable natural resource, with one of its biggest problems being that it is non-renewable/finite. Once it is eroded, it cannot be replenished; at least, not for a very long time. Therefore, the conservation of soil & the prevention of soil erosion are challenges that face millions of people if they wish for their future food supplies to remain secure, while also maintaining a sufficient and stable food supply in the present.

Two ways in which humans can strive to conserve soils:

• Replacing and improving vegetation cover - Given that the most serious cause of soil erosion is the removal of vegetation cover, the best protection would appear to be the planting of vegetation. Reforestation & afforestation are long term solutions, as growing vegetation intercepts rain drops, thus lessening the damaging effects of rain-splash. The roots of such vegetation bind soil together, reducing surface runoff and the likelihood of erosion. The roots also absorb moisture from the soil reducing the weight and therefore, potential movement of the soil. The growing of cover crops, especially grasses, for short periods on newly ploughed lands reduces surface runoff and rain splash, by covering and binding the soil. Such grasses can also trap wind-blown particles. In addition, stubble planting can aid soil conservation. In the past, the stubble of crops harvested in a year was ploughed straight back into the soil to improve fertility. Now, though, stubble is left on the surface so that its roots can reduce wind and rain erosion by binding the top layers together. In time, it will still rot and act as a source of humus. Furthermore, the planting of trees as windbreakers or barriers around the edges of fields can be another beneficial and worthwhile activity. The trees slow down and stop the wind from blowing the soil away, sheltering and protecting it. However, the windbreakers/barriers should try to allow a little wind through. If a wall of trees stops the wind completely, violent gusts can occur close to the ground. These gusts have the capacity to lift soil into the air and then blow it away. To avoid this, effort should be made to plant two separate lines of trees; one tall and one short. The addition of humus also helps to reduce soil erosion, as the humus absorbs and retains water. This reduces the chances of the soil drying up and being blown away.

• Improving water control and reducing surface runoff - Water wells sunk in dry climates use up reserves of groundwater, resulting in the lowering of the water table. This makes it harder for roots to reach water & eventually the soil will dry up entirely. Careful control of well sinking and the amount of water used would reduce this problem. Contour ploughing is another novel idea; this is where famers follow the contour around a hillside, as opposed to ploughing up-and-down. The furrows and ridges created by the plough act as mini-terraces, slowing or stopping the flow of rainwater downslope and thus allowing the water time to soak down through the soil. This also reduces gully erosion (where rainwater erodes small valleys into a landscape). In the case where a hillside is too steep for contour ploughing, artificial terraces can be constructed e.g. a series of parallel walls. These will function in the exact same manner. They can even be designed in such a way that behind each wall, the land could be flattened out and used to grow crops. Alternatively, crude stone walls/bunds, could be put up as simple water control measures. Here, small stones are placed in lines along the contours of the hillside. Again, rainwater gets trapped behind the stones, allowing it time to percolate down into the soil.