EFFECTS OF MODERN AGRICULTURE

• Agriculture has been considered as a way of life. Ever increasing population places greater demands on agriculture to increase the production, to match the increasing demands for food supply.

• With agricultural development though food production has successfully increased nearly everywhere but it has failed to match with the growing population in many areas - specially developing countries of Africa, Asia and Latin America.

Over the period of time, the development of agriculture was achieved in terms of:

• Expansion and /or conversion of agricultural lands

• Increased agricultural productivity• Multiple-cropping pattern• Conversion of single-cropping system to two

tier / or three tier cultivation• Expansion of natural limits.

In due course of time, agricultural development became possible due to

• Development of modern scientific techniques• Advanced technology • Expansion of irrigational facilities • Use of chemical fertilizers• Use of pesticides and insecticides • Development and use of high yielding varieties of seeds • Changed agricultural practices • Mechanization of agriculture • Varying crop sequences and • Land ownership and the land tenure.

 Expansion and Conversion of Agricultural Land

• Conversion and expansion of agricultural land and forest areas changes in their natural limits. Thousands of millions of tons of soil is lost annually due to large-scale deforestation and/ or poor land management records chain reaction in the broad areas.

Application of Chemical Fertilizers, Pesticides and Insecticides

• Fertilizer application in South Asia including India has multiplied with widespread introduction of the Green Revolution. Not only the number of fertilizer plants has gone up but also the production has multiplied, resulting in many a disorder.

 The High Yielding Varieties Programme

• The introduction of high yielding varieties has changed the agricultural environment by creating a variety of pest problems. Many of these either were unknown or were of minor importance in the early sixties.

• The increased irrigational facilities, higher use of fertilizers and the high yielding varieties led to the resurgence of pests.

Development of Irrigational Facilities

• The multiple cropping and intensive uses of chemical fertilizers and heavy watering of the agricultural land result in the rise of the water level. As a result, such areas have developed the problem of water logging, ultimately damaging the standing crops, microorganisms, animals and even the human population.

 Intensive and Extensive Cultivation

• The introduction of intensive cultivation to get the maximum production and the variety of crops through multiple cropping, crop-rotations, changing crop-combination from the same unit of land has resulted in the decline of the productivity and total production due to critical limit of the soil.

Mechanisation

• The use of tractors, combined with harvesters increased with suitable machinery to work on difficult soils became practicable and has brought such lands under plough. Increasing use of machinery arid tractors with the development of two-tier and/or three-tier cultivation system has pulverized the land.

FERTILIZERS & INSECTICIDES

• Substances which are added to the soil to increase its fertility are called Fertilizers.

• Many natural substance like leaves, cow dung, bone meal compost etc are used to make up the deficiency of nitrogen , phosphorus and potassium in soils. These substance are known as natural fertilizers.

Artificial inorganic fertilizers (Synthetic fertilizers)

Nitrogenous fertilizers: Important nitrogenous fertilizers are 1) Ammonium sulphate

2) Ammonium phosphate

3) Calcium Cyanamid

4) Urea

Phosphatic fertilizers:-

Important phosphatic fertilizers are 1) Super phosphate of lime ( Calcium super phosphate)

2) Triple super phosphate

3) Ammonium superphosphate

    Mixed fertilizers:- 

• A fertilizer which contains more than one plant nutrients is called mixed fertilizer.

• Mixed fertilizer Containing nitrogenous, phosphatic and potash fertilizers in definite proportions.

• Such fertilizers are called NPK fertilizers

    Impact of excessive use of     fertilizers on environment 

• The increased use of fertilizers to expand food supplies have come at a large cost to our environment.

•  Modern agricultural techniques are typically wasteful in their use of fertilizers.

• Often, many farmers add large amounts of fertilizer or manure at the time of sewing in order to cover and protect the young plants.

• This technique is inefficient, since the young plants are unable to absorb most of the nitrogen.

• Therefore, much of the nitrogen is lost to the environment in a number of ways.

BIO FERTILIZERS:

Biofertilizers are ready to use live formulates of such beneficial microorganisms which on application to seed, root or soil mobilize the availability of nutrients by their biological activity in particular, and help build up the micro-flora and in turn the soil health in general.

Benefits from using biofertilizers

•Increase crop yield by 20-30%.

•Replace chemical nitrogen and phosphorus by 25%.•Stimulate plant growth.

•Activate the soil biologically.

•Restore natural soil fertility.

•Provide protection against drought and some soil borne diseases.

Advantages of bio-fertilizers

1.Cost effective.

2.Suppliment to fertilizers.

3.Eco-friendly (Friendly with nature).

4.Reduces the costs towards fertilizers use, especially regarding  nitrogen and phosphorus. 

PESTICIDES

•Pesticides are chemical substances used to kill insects, fungi, rodents,weeds or other living things which are harmful to plants, animals or foodstuffs.

•Pesticides function as poisons for the important biological process of insects, fungi etc which lead to the death of these organisms.

Classification of pesticides

• Depending upon the purpose for which the pesticides are used, they are classified as

follows.

• i) insecticides v) algaecide • ii) herbicide vi) molluscicides • iii) fungicides vii) miticides • iv) rodenticides viii) nematocides.

Insecticides:-

•Chemicals used to kill the insects are called insecticides. Insecticides are further classified into Stomach poisons, contact poison and fumigants .Herbicides• Herbicides are used to destroy weeds (destroy the growth of plants).

eg: 2,4 D (2,4 dichloro phenoxy acetic acid)

Fungicides:- •Fungicides are are chemicals which are used to prevent the growth of fungi or eradicate fungal diseases of plants. Eg: Lime, sulphur, formalin etcRodenticides:-•These are chemicals used to kill rats and mice which destroy crops and spread deseases. Eg: Sodium fluoroacetate, Zinc phosphide etc

Algaecide:-

•These are chemicals added to water to destroy algae. Eg: copper sulphate

Molluscicides:- 

•These are chemicals used to destroy mollusks like snails , slugs etc eg: Copper sulphate, metaldehyde etc

Miticides:- 

•Chemicals used to destroy mites are called miticides .eg: organo phosphates. Nematocides:- 

•These are chemicals used for the distruction of nematodes like round worms, thread worms etc . eg: dimethoate

Environmental impact of pesticides 

The excessive use of pesticides have created tremendous adverse effects on environment

 1) Environmental pollution:-

    Pesticides drained to water bodies causes water pollution . hence water in river, lakes and seas gets polluted which becomes hazardous to aquatic animals like fishes.

Pesticides may also washed down to ground water which pollute drinking water. During the spraying of pesticides it may reach in to atmosphere and pollute the air.

• Certain pesticides such as DDT, BHC etc persisted in the environment accumulated in blood,milk and fat of animals.Beyond certain permitted levels, they are very dangerous to human beings and animals

• Pesticides may kill the friendly insecticides along with the inimical insects during its action

• Different herbicides used for destroying weeds can destroy the vegetation in the neighboring areas also.

• Repeated use of pesticides may produce immunity or resistance in insects. Resistance has been observed in houseflies, mosquitoes etc.

• Effect on human health ;- Pesticides cause several harmful effects in human body. Pesticides are proved to be lethal if their intake exceed a maximum limit.