Write an essay on Soil Pollution ?

Soil constitutes the upper crust of the earth which support land plants and animals. Like air and water, soil also gets polluted. Soil pollution can be defined ‘the addition of substances to the soil, which adversely affect physical, chemical and biological properties of soil and reduces its productivity. The process of soil formation is very slow, therefore the soil may be considered as non-renewable resource. This makes the problem of soil pollution more acute.

Soil pollution is an extremely complicated process. It may occur directly by dumping, and disposal of wastes, application of agro-chemicals or the indirect result of air pollution such; as acid rains. The main soil pollutants are : (i) industrial wastes (ii) pesticides (iii) fertilizers and manures (iv) discarded wastes (v) radioactive (vi) other pollutants.

(i) Industrial wastes : Both solid and liquid wastes of industries are dumped over the soil. The wastes contain a number of toxic chemicals such as mercury, lead, copper, zinc, cadmium, cyanides, thiocynates, chromates, acids, alkalies, organic substances etc. Some toxic chemicals reach by mining operations also.

(ii) Pesticides:  Now-a-days a number of chemicals are used to kill insects (insecticides), fungi (fungicides), algal bloom (algacides), rodents
(rodenticides), weeds (weedicides or herbicides) in order to improve agriculture, forestry and horticulture. They are sprayed on plants in the form of fine mist or powder. Most of the pesticides are broad spectrum and effect all types of life. They are, therefore, also called “biocides”. Pesticides reduce the population and number of species of living organisms including micro organisms, thus effect the structure and fertility of soil. Several pesticides or their degradation products are absorbed by plants which in turn may affect the entire food chains and food webs.

(iii) Fertilizers and manures: Chemical fertilizers are added to the soil for increasing the crop yield.  The excretory products of people and livestock and digested sewage singe used as manure pollute the soil. The innumerable pathogens contained in these wastes contaminate the soils and vegetable crops and cause serious health hazards for man and domesticated animals. However, biological sources are the minor factors in altering soil composition.

(iv) Discarded materials: A large number of discarded materials are dumped on the soil by man. These include concrete, asphalt, rugs, leather, cans, plastics, glass, discarded food, paper and carcasses. The addition of solid wastes is sometimes called the third pollution.

(v) Radioactive wastes : Radioactive elements from mining and nuclear power plants, find their way into water and then into the soil.

(vi) Other pollutants : Many air pollutants (acid rain) and water pollutants ultimately become part of the soil. The soil also receives some toxic chemicals during weathering of certain rocks.

 

What is soil erosion? Explain its types and causes ? 

Soil is the upper weathered humus containing part of the earth’s surface. It can sustain terrestrial plant life, this fertile layer of soil is top soil. Soil erosion is removal of top soil from one place to other by the external factors like air and water. In India there is loss of 300-500 lakh tones grains every year due to soil, loss. Three kinds of soil erosions are

 (i) Natural erosion : It occurs in natural conditions. It is not influenced directly or indirectly by man. It is very slow process of soil erosion.

(ii) Fast Soil erosion : It is quick process of erosion in which soil erosion is faster than soil formation, soil loss is greater and animals and man are responsible for fast soil erosion.

(iii) Water Erosion : In water erosion the soil is chiefly eroded by water in three forms, viz.

(1) In sheet erosion, the soil is eroded as a layer from the hill slopes, sometimes slowly and insidiously and sometimes more rapidly. Sheet erosion is more or less universal on : (a) all bare fallow land : (b) all uncultivated land whose plant cover has been thinned out by grazing, fire or other misuse; (c) all sloping cultivated fields and on sloping forest and scrub jungles whose natural porosity of soil has been reduced by heavy grazing, clear felling of trees or burning. Sheet erosion is common in the Himalayan foothills; over the north-eastern parts of the peninsula; in Assam and in the Western and Eastern ghats.

(2) When sheet erosion is allowed to continue unchecked, the silt- laden run-off forms well-defined minute finger-shaped groves over the entire field. Such thin channeling is known as rill erosion. Such type of erosion is active over a wide area in Bihar, U.P., M.P., and in semi-arid areas of Maharashtra, Karnataka, Andhra Pradesh and Tamil Nadu.

(3) In gully erosion, the water forms small rivulets which wash away the soil from bullies. First there is the main ravine and then side checked, goes on extending and ultimately the whole land is converted into a ‘bad land topography’. Gully erosion is more common (a) where the river system has cut down into elevated plateaus so that feeders and branches carve out an Intricate pattern of gullies; and (b) in relatively level Country whenever large blocks of cultivation give rise to concentration of field run-off. The chose of Northern Haryana and Punjab and the bedland of M. P, Rajasthan and U. P., have been formed because of the gully erosion on an extensive scale.

(4) During sudden floods, the fast flowing river undercut the banks I erode the beds. Wherever there is a bend the flowing water gets suddenly and due to increased torsion the Outer bank caves alongside. The eroded material is deposited along the opposite bank nearby. This is known as stream, bank erosion.

Causes of Soil Erosion :

The main factors (causes) of Soil Erosion are as follows :

1. Deforestation : The destruction of forest covers for the supply of Limber and fuel by deliberate human interference leads to increased run-off rain water and its diminished seepage and storage in the soil. The decomposing forest little is no longer replenished by fresh falls of leaves or decaying roots so that plant remains and soil organic matter gradually diminish. The structure of the soil suffers, the run —off increases. It loosens soil and transport it. The water develops power enough to cause devastating floods.

2. Destruction and Overgrazing of Pastures : A properly manage, lightly grazed pasture might form a permanent protection to the soil because it provides an efficient cover for preventing erosion and reducing run-off in much as it covers the surface of the ground protecting it from the direct impact of the falling rain drops and thus keeping the pores of the soil open and capable of receiving excessive amounts of water. But when there is over-grazing by cattle, goats and sheep, the soil becomes uncovered as the grass over-gazed becomes worn and thin, rain drops begin to fall directly on the soil puddling the surface and clogging up the pores with mud. Infiltration into the soil is reduced and the fun-off of the water increases. All this .invariably leads to a deterioration in botanical composition and an Increase In the growth of weeds as well as to an increase in the area of bare ground.

3. Shifting Cultivation : Man’s furthless destruction of the forest for shifting cultivation has also decreased the area under forest. Shifting or Jhuming cultivation is chiefly practiced by the primitive tribes for raising food for them. According to this system of farming a patch of forest is selected. Its trees and bushes are then cut and burnt down on the ground in order to clear room for a field. The ground is, then, lightly ploughed and the seed is sown broadcast and raked into the soil, at the first fall of the rains which is immensely fertile owing to the wood ashes and accumulated humus.

4. Economic and Social Factors : Certain economic factors arising out of the traditional outlook, social economy and economic structure of the community have also indirect bearing on the soil erosion. Of these, the system of farming, size of the farm tenancy, tenant-landlord relationship are too significant facts to be over looked. Bad agricultural practices also lead to I the loss of top fertile soil.

5. Nature of Crop Grown : In arable agriculture, crops vary widely in their effect on erosion losses While barely, oats and wheat have “low Units of index” of soil loss; corn, sorghum, cotton, soyabean have “higher units of index.”

Write down the Importance of soil? Give necessary suggestion to control the problem of desertification.

Importance of soil

Like rains, soil is also an important factor. Plants depend for their nutrient, water supply and anchorage upon the soil free floating, aquatic plants which derive their nutrients dissolved in water medium around them, soil is the chief storage of all the nutrients, which may available to the water medium. So soil system is indeed a complex and dynamic. Soil may affect plants by affecting seed germination, size and erectness of the plant, vigor of vegetative organs, woodiness of stem, depth of the root system, susceptibility to drought, frost and parasites, number of flower per plant and time of flowering.

Warning: (1909) has proposed five ecological groups of plants.
(1) Oxylophytes : found on acid soil.
(2) Halophtyes found on saline soil.
(3) Psammophytes found on sand.
(4) Lithophytes : found on rock surface.
(5) Chasmophytes : found in rock services.

Give necessary suggestion to control the problem of desertification.

Necessary suggestion to control the desertification:

(1) To control on animal pasture.
(2) Change in agriculture system.
(3) Spread human-conscious towards desertification.
(4) Right use of available water resources.
(5) Plantings in desert area.
(6) Ban on tree cutting.
(7) To ban unmanagable stone mines.
(8) To apply to desert develop programme.
(9) To make available other resources for fuel.
(10) Planting on hill area and other open area.
(11) To tell the local people about the famine and importance of trees.