What is soil pollution?

What is soil pollution?

The contamination of soil with solid waste, chemicals (through industrial wastes or acid rain), fertilizers and pesticides, reducing its fertility is called soil pollution.

Types of soil

Soil is broadly classified in the following three types :

1. Sandy soil: It contains more sand (90%) and less clay (10%). It is permeable to air and water due to large pore spaces which dry up very easily. It is suitable for fruits and vegetables.
2. Clayey soil:  It has a high portion of clay. It becomes sticky in water. It is not aerated (air spaces). Roots find difficulty in penetration and it gets waterlogged in high moisture. It becomes suitable for farming by adding sand and time.
3. Loamy soil: It is a mixture of sand and clay together with silt and humus. It is most suitable for plant growth.

Why Tilling of soil is important ?

• Allows the roots to penetrate deep into the soil.
• Allows easy breathing of roots.
• Tilling loosens the soil that helps in the growth of earthworms and other microbes which further turn and loosen the soil.
• Adds humus to the soil.
• Brings about nutrient rich soil to the top, so that plants can use these nutrients.

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Sources of soil pollution

The main sources of soil pollution includes:

1. Solid wastes : The solid wastes coming from residences, cattle sheds, industries, etc. make the surroundings dirty and pollute the soil.
2. Chemicals : The industrial wastes consisting of a lot of chemicals are generally dumped in vacant sites and they pollute the soil. Some chemicals discharged into the air eventually come down as dry deposition or as acid rain and pollute the soil.
3. Excess of fertilizers and pesticides : Fertilizers and pesticides when used in excess in agricultural fields pollute the soil. From the soil, many non-biodegradable chemicals (e.g., DDT) even enter the food chain and show biological magnification.

Harmful effects of soil pollution

1. Soil pollution reduces the fertility of soil leading to reduction in crop yields.
2. Solid waste makes the surroundings dirty and also emit foul smell due to their decomposition.
3. Soil pollution may kill and reduce the diversity of organisms living in the soil including the earthworms, micro-organisms etc. which are instrumental in making the rich humus.

SOIL EROSION

Soil is a complex mixture of non-living materials and living organisms. It provides anchorage to plants and is also a source of nutrients and water to the plants. Majority of the plants, thus, grow in the soil. The top layer of soil is very fertile and is often carried by environmental agencies.

This removal of the top layer of the soil from one place to another by certain agents such as strong winds, fast flowing water, is called soil erosion.

Causes of soil erosion

The various causes of soil erosion are:

• Strong winds : Strong winds carry away the loose top soil when it is uncovered.
• Heavy rains : Heavy rains or frequent floods wash away unprotected top soil down into the streams, rivers, etc.
• Improper farming and suspended cultivation : Farmers loosen the top soil of agricultural fields for cultivation or for removing the weeds. Sometimes, due to certain reasons, when these fields remain uncultivated for a long time it becomes prone to erosion.
• Human activities : Large scale deforestation by humans lead to soil erosion.

Effects of soil erosion 

The various effects of soil erosion are loss of fertility, desertification, landslides, floods, etc,

Prevention of soil erosion 

Certain measures can effectively reduce soil erosion. These include intensive cropping, sowing grasses in uncultivated land, terrace farming along the slopes of hilly areas, making embankments along the river banks, etc.