Agriculture

. It comprise animal husbandry and crop production Agriculture was the first man made modification of ecosystem which occurred due to compulsion of increasing human population and difficult in procuring food. At that time human being had learnt the use of fire. They domesticated some animals and therefore created an artificial ecosystem for them. They raised crops and created an artificial agroe cosy stem. In older days agroecosystem were temporary as they were raised by temporary as they were raised by cutting down forests cultivating the land for a couple of years and then abandoning the site. Now-a-day agro-ecosystem are of permanent nature though they cannot survive without our support. Pasture or pastoral land is similarly prepared for feeding domestic animals. Both crop lands and pastoral lands are essentially grasslands with choice plants since they have been mostly created by clearing grasslands. Forests have also been removed for this purpose at several places.
The study of relationships between agriculture crops and their surrounding animate as well as inanimate environment is called agroecology, agroecosystem are different at different places depending upon latitude, edaphic factors topography and climate factors. The crops mainly belong differs from area to area, season to season depending upon climate and preference of the farmers. The biotic community is the richest when the crop is in the field. It consists of some weeds pest’s earthworms, nematodes, insect’s rodents, many birds, pollinators, domestic animals and decomposers. AH agroecosystem have some common features. The important ones are:

• They are man-powered and artificial.


• The ecosystems do not have self-regulatory mechanisms.


• There is little natural circulation of biogenetic nutrient.


• Stability of an ecosystem depends upon diversity. Croplands are mostly monocultures and lack diversity.


• They are vulnerable to destruction due to drought, floods, disease pathogens and pests. Irish famine and Bengal famine are two such examples.


• They are artificially irrigated, aerated and provided with required biogenetic nutrients in the form of fertilizers. The latter cause pollution of ground water as well as nearby above ground water bodies.


• They are protected against weeds, pathogens and pests through chemicals. The chemicals are toxic to other living beings including human beings.


• Technology is being increasingly used in raising and reaping crops.


• Modern day crop plants have been modified genetically to give very high yields, several times those of natural ecosystems.
• Biomass is not allowed to accumulate due to reaping. The stubbles are burnt these days. Manures are added to the soils to keep them healthy.