Soil Conservation – Various Methods – Crop Rotation, Strip Cropping, Contour Ploughing, Mulching, Terrace farming, Shelter belts, Sand fences.
- Soil conservation is the prevention of soil from erosion or reduced fertility caused by overuse, acidification, salinization or other chemical soil contamination.
- Soil erosion is the greatest single evil to Indian agriculture and animal husbandry.
- Notable Quotable from Kullar’s Indian Geography: “With soil conservation people rise and with its destruction they fall. Neglect of soil is like killing the hen that lays the golden egg.”
- Adopting sustainable agricultural practices is the most important measure to conserve soil.
- In many parts of India, a particular crop is sown in the same field year after year. This practice leads to exhaustion of certain nutrients in the soil making it infertile.
- Crop rotation is a practice in which a different crop is cultivated on a piece of land each year.
- This helps to conserve soil fertility as different crops require different nutrients from the soil. Crop rotation will provide enough time to restore lost nutrients.
- For example, potatoes require much potash but wheat requires nitrate. Thus it is best to alternate crops in the field.
- Legumes such as peas, beans, and many other plants, add nitrates to the soil by converting free nitrogen in the air into nitrogenous nodules on their roots. Thus if they are included in the crop rotation nitrogenous fertilizers can be dispensed with.
- Crops may be cultivated in alternate strips, parallel to one another. Some strips may be allowed to lie fallow while in others different crops may be sown.
- Various crops are harvested at different intervals. This ensures that at no time of the year the entire area is left bare or exposed.
- The tall growing crops act as wind breaks and the strips which are often parallel to the contours help in increasing water absorption by the soil by slowing down run off.
Use of Early Maturing Varieties
- Early maturing varieties of crops take less time to mature and thus put lesser pressure on the soil. In this way it can help in reducing the soil erosion.
- If ploughing is done at right angles to the hill slope, the ridges and furrows break the flow of water down the hill.
- This prevents excessive soil loss as gullies are less likely to develop and also reduce run-off so that plants receive more water.
Checking Shifting Cultivation
- Checking and reducing shifting cultivation by persuading the tribal people to switch over to settled agriculture is a very effective method of soil conservation.
- This can be done by making arrangements for their resettlement which involves the provision of residential accommodation, agricultural implements, seeds, manures, cattle and reclaimed land.
Ploughing the Land in Right Direction
- Ploughing the land in a direction perpendicular to wind direction also reduces wind velocity and protects the top soil from erosion.
- The bare ground (top soil) between plants is covered with a protective layer of organic matter like grass clippings, straw, etc.
- Protects the soil from erosion.
- It helps to retain soil moisture.
- Reduces compaction from the impact of heavy rains.
- Conserves moisture, reducing the need for frequent watering.
- Maintains a more even soil temperature.
- Prevents weed growth.
- Organic mulches also improve the condition of the soil. As these mulches slowly decompose, they provide organic matter which helps keep the soil loose.
- Stones, grass, soil are used to build barriers along contours. Trenches are made in front of the barriers to collect water.
- They intercept downslope flowing water and soil particles. These barriers slow down the water movement and reduce its erosive force. They also filter out and trap many of the suspended soil particles, keeping them from being washed out of the field.
- A long term advantage of barriers is that soil tends to build up behind them, creating a terrace effect. Barriers can be classified as live (strips of living plants), dead (rocks, crop residues), or mixed (a combination of the previous two).
- Rocks are piled up across a channel to slow down the flow of water. This prevents gullies and further soil loss.
- In terracing, a number of terraces are cut along the hill slope.
- These are made on the steep slopes so that flat surfaces are available to grow crops. They can reduce surface run-off and soil erosion.
- Contour bunding involves the construction of banks along the contours.
- Terracing and contour bunding which divide the hill slope into numerous small slopes, check the flow of water, promote absorption of water by soil and save soil from erosion.
- Retaining walls of terraces control the flow of water and help in reducing soil erosion.
- Different crops are grown in alternate rows and are sown at different times to protect the soil from rain wash.
- Ploughing parallel to the contours of a hill slope to form a natural barrier for water to flow down the slope
Shelter belts or Windbreaks
- In the coastal and dry regions, rows of trees are planted to check the wind movement to protect soil cover.
- Sand fences are barriers made of small, evenly spaced wooden slats or fabric. They are erected to reduce wind velocity and to trap blowing sand. Sand fences can be used as perimeter controls around open construction sites to keep sediments from being blown offsite by the wind.
- It includes the prevention of forest destruction along with growing new forests or increase area under forests.
- A minimum area 20 to 25 per cent of forest land was considered healthy for soil and water conservation for the whole country.
- It was raised to 33 per cent in the second five year plan – 20 per cent for the plains and 60 per cent for hilly and mountainous regions.
- Overgrazing accentuates erosion. During the dry period, there is shortage of fodder and the grass is grazed to the ground and torn out to the roots by animals. Soil is pulverized (reduce to fine particles) by the hoofs of animals. All this leads to weak top layer.
- So overgrazing needs to be checked to prevent soil erosion.
- This can be done by creating separate grazing grounds and producing larger quantities of fodder.
- Much of the soil erosion by river floods can be avoided by constructing dams across the rivers in proper places. This checks the speed of water and saves soil from erosion.
- But indiscriminate dam construction can worsen the condition by creating floods and landslides like it happens in the Himalayan region.