Land Degradation and Its Causes
The deterioration in the quantity of land and a reduction in its fertility and productivity is called land degradation. And the Soil Erosion is the major factor that causes land degradation.
The factors causing land degradation are:
- Soil erosion
- Shifting cultivation
- Soil pollution
- Salination and water-logging Urbanisation
Loss or removal of the superficial layer of the soil by the action of water, wind or by the activities of man termed as soil-erosion.
Factor Affecting Soil Erosion
The factors were affecting soil erosion given below.
Amount, intensity and distribution of rainfall
Exceptionally high rainfall in short duration and intense rain causes more soil erosion.
The slope of the ground
The ground with steep hill causes more soil erosion.
Nature of soil
Soil erosion will be more in case of loose soil than dense and heavier soils.
Vegetation cover reduces the runoff and prevents soil erosion.
Faulty methods of surface irrigation, overgrazing, wrong methods of cultivation (Cutting fields along the direction of hill slopes), forest fires etc.
Soil pollution may define as the addition of substances to the soil which adversely affect physical, chemical and biological properties of soil, reducing its fertility and productivity.
So, the Soil pollution reduction in the productivity of soil due to the presence of soil pollutants.
Soil pollutants include pesticides, fertilisers, organic manure, chemicals, radioactive wastes, discarded food, clothes leather goods, plastic paper, bottles, and tin cans biomedical waste etc.
Common Causes of Soil Pollution
- Disposal of domestic wastes
- The Disposal of agricultural wastes and Disposal of industrial wastes
- Use of pesticides for protecting crops
- Use of chemical and biological fertilisers
- Disposal of radioactive and nuclear wastes
- Disposal of biomedical wastes
- The intrusion of seawater
- Oil leakage from storage tanks, pipeline
Effects of Soil Pollution
Soil pollutants have an adverse impact on the physical, chemical and biological properties of the soil and reduce its productivity or fertility.
Pesticides, fungicides and some metallic elements like Cu, Hg, Pb, As, etc. Furthermore, these elements are very harmful to the beneficial micro-organisms in the soil as they affect the soil fertility.
The excessive use of fertilisers makes the soil either too acidic or too alkaline making it unfit for crop growth.
Moreover, Soil pollutants can also clog the pores in the soil due to which air circulation is not possible, so the micro-organism in the land which is beneficial for the growth of plants cannot get enough oxygen for there survival. This results in the decrease in productivity of the soil.
Salination and Water Logging
Increase in the concentration of soluble salts in the soil called Salination. So, it adversely effects soil productivity and degrades the quality of land. Salination caused by a number of processes.
Due to poor drainage, salts from irrigation and flood water will accumulate on the soil surface. The salts from the lower layers move up by capillary action in summer and deposited on the surface.
So, In coastal regions, winds bring a lot of salt from raw water to land, thus causing Salination of the soil.
Excessive use of alkaline fertilizers such as sodium nitrate may cause salinationof the soil.
In shifting cultivation, selected portions of the forest are cut and burnt. Crops are cultivated on that land for some years till it becomes sterile. Then fresh fields formed for crop cultivation.
So, this practice has led to complete destruction of forests in mainly hilly areas of India and caused soil erosion and problems that accompany soil erosion.
Wind causes the shifting of sand dunes from one place to another, increasing the proportion of fertile land getting converted into deserts each year excessive grazing by livestock is another factor resulting in desertification.
The destruction of natural vegetation results in accelerated soil erosion due to the removal of the vegetation cover. Erosion of the top fertile soil results in loss of soil productivity and formation of deserts.
So, The immediate cause is the removal of vegetation. Unprotected, dry soil surfaces then blow away with the wind or are washed away by flash floods, leaving infertile lower soil layers.
All the factors causing soil erosion leads to deforestation, the main factors being over cultivation, grazing and deforestation.
Due to urbanisation, people are moving from the villages to towns and cities. Therefore, cities are expanding rapidly converting the fertile, productive land into the infertile land.