Solid wastes

 Soil pollutants and their effects

Agrochemicals-pesticides and weedicides :

A number of chemicals have been developed to kill a variety of pests in order to improve agriculture, forestry, horticulture and water reservoirs.

The most widely used among them are insecticides.

Most of these insecticides are broad spectrum and affect other animals, man and even plants.

They are, hence, also called biocides.

These include:

(i) Organo insecticides: They include DDT, PCB, Aldrin, BHC (benzene hexachloride) etc. Chlorinated hydrocarbons are toxic. Besides being toxic, these pesticides are both persistent and mobile in the ecosystem. The chlorinated hydrocarbons like DDT results in biological magnification.

Organophosphorus compounds (e.g., malathion, parathion) and organocarbamates are degradable but they influence the nervous system.

(ii) Weedicides (Herbicides) : The weedicides or herbicides are usually metabolic inhibitors which stop photosynthesis and other metabolic activities and hence kill the plants.

2. Industrial wastes:

Both solid and liquid wastes of the industry are dumped over the soil.

The wastes contain a number of toxic chemicals like mercury, copper, zinc, lead, cadmium, cyanides, thiocyanates, chromates, acids, alkalies, organic solvents etc.

3. Mine dust:

It is a major source of poilution in mining areas.

Mine dust not only spreads with wind but also spread over a large area during transportation to purification plants.

4. Fertilizers:

Excessive use of chemical fertilizers causes soil deterioration through the decrease in natural bacterial population (nitrogen fixing, nitrifying, etc.) and destruction of crumb structure.

The salt content of the soil is also bound to increase with continuous use of fertilizers.

Case Study of Organic Farming

Integrated organic farming is a cyclical, zero-waste procedure, where waste products from one process are cycled as nutrients for other processes.

This allows the maximum utilisation of resources and increases the efficiency of production.

Ramesh Chandra Dagar, a farmer in Sonipat, Haryana, is doing just this. He includes bee-keeping, dairy management, water harvesting, composting and agriculture in a chain of processes, which support each other and allow an extremely economical and sustainable venture.

There is no need to use chemical fertilisers for crops, as cattle excreta (dung) are used as manure.

Crop waste is used to create compost, which can be used as a natural fertiliser or can be used to generate natural gas for satisfying the energy needs of the farm.

Enthusiastic about spreading information and help on the practice of integrated organic farming, Dagar has created the Haryana Kisan Welfare Club, with a current membership of 5000 farmers.