Essay on Wastage and Degeneration of Soils

Through an essential natural resource we often fail to realize the tremendous importance of
soils underneath us. Mankind can live without fossil fuels but it cannot survive the depletion of this thin crust of loose material on which we depend for our food supplies.

However, with an ever-rising population and pressure of demand on our natural resources, degeneration of soils has already begun. We are losing almost 7 million hectares of useful cropland every year (U.N., F.A.O. Report 1980). There are three basic reasons for loss of soil and its degeneration to a useless heap of lifeless material:

1. Modern agricultural practices. 2. Deforestation.

3. Diversion of prime cropland to other uses.

(1) Modern Agricultural Practices:

Modern practices of intensive agriculture contribute much to the deterioration of agricultural soils. Much of the degeneration stems from stress, exposure and damage to the microbial community of the soil. As the soil-life and organic matter content gradually diminishes, the soil is turned into dead rock fragments. Some of the damaging aspects of modern agricultural practices are:

1. We level ground and plant crops over an enormous stretch of land. There are no trees, shrubs or other impediments in-between. This exposes the soil to battering action of rains, wind and water currents. Extensive soil erosion follows.

2. Little fallow periods are allowed in-between crops. The soil is unable to recover its nutri­ents before the next crop is sown. Chemical fertilizers have to be added to maintain pro­ductivity. As organic matter gradually disappears, soil-crumb structure degenerates and soil is reduced to a heap of sand, silt and clay.

3. In poorly drained soils regular use of chemical fertilizers causes problems of salinity, alkalinity or acidity. The entire fertilizer molecule is not required by the plants. Some of the constituent ions are taken up others are left behind which accumulate in the system and cause problems later. For example application of (NH₄)₂ S0₄ as fertilizer causes the soil to become acidic as ammonium ions are selectively absorbed while sulphate ions are left behind which make the soil acidic. Normal soil micro flora is disturbed.

4. Irrigation by tube well or river water is also injurious to soils under conditions of poor drainage. These waters contain plenty of salts which are left behind as water evaporates or is transpired by crop plants. In the long run the soil becomes salt-infested as there is little drainage which could remove the salt.

5. Pesticides sprayed on crops are ultimately washed down to soil where they kill or damage the microbial community. Normal functions of the soil are disturbed. Soils lose their capacity of nutrient regeneration while soil-particle-aggregates disintegrate making the soil prone to erosion.

6. Use of modern, high-yield, synthetic varieties which require large quantities of nutrients, in absence of adequate fertilizer input deplete the soil of its natural nutrients. This causes loss of fertility and soil degeneration.

7. Shifting cultivation, an age-old practice, contributes much to wastage and degeneration of fertile soils. Due to the pressure of demand, adequate gap period for regeneration of fertility and plant cover is not provided to the soil before next cycle of farming is started. The productivity has to be maintained by using chemical fertilizers. The fragile soil is soon converted to a useless heap of sand, silt and clay.

8. The pressure of demand on agricultural products causes people to extend cultivation on marginal soils, like hill tops and slopes, desert and semi-desert regions. This is more hazardous. Soil at these places is already in a fragile state. Cultivation, use of chemical fertilizers, pesticides etc. degrade these soils quickly and almost total desertification fol­lows.

(2) Deforestation:

No doubt expansion of agriculture is the primary cause of extensive destruction of natural vegetation. Human requirement for timber, fuel-wood and space has laid bare, large portions of otherwise fertile land. This leaves the soil unprotected for the action of strong wind and rapidly flowing water. Forest cover is exceedingly helpful in protection of soil because:

1. Plants bind the soil particles together and check erosion.

2. Plants keep the surroundings humid and moderate extremes of temperatures.

3. Plants offer impediment to the strong currents of air and water.

4. Plant cover retains water for longer periods on the soil surface so that it percolates down and recharges ground water aquifers.

5. Larger trees, bushes etc. protect the microbial communities of the soil from direct expo­sure. They also provide organic matter for their maintenance.

6. Forests are helpful in attracting rains which in turn promote growth of green cover over the soil.

Much of our soils under intensive agriculture are already in a fragile state. To this is added large area of adjoining deforested land. There is little obstruction to the flow of strong winds and water currents. Strong winds promote rapid drying and carry away the precious soil as dust or sand storm to be deposited elsewhere. Similarly rains which often tend to visit such areas in strong torrents cause extensive erosion of fertile soils. With soil erosion, follows desiccation and desertification. The fertile stretch of land is turned into a barren landscape or a dust bowl.

(3) Diversion of Prime Crop-Land to Other Uses:

The most important role of soil is to produce food for mankind. However, in spite of shortages of food and other edible products, prime agricultural land is being diverted to other uses. Most of our cities stand on the best and the most productive land. It was only on the best fertile land Thai man settled in villages to look after the agriculture. It is these villages which have expanded into towns, towns into cities and cities into metropolis due to agricultural productivity only.

Availability of labour, capital, raw material, large markets etc. at these places has given rise to much of industries and has caused a steady enlargement of cities at the expense of best productive land. Ever expanding human settlements, industries, roads, railway tracks, military establishments etc. engulf enormous area of land annually which if used for agriculture could feed millions of hungry people.