Food is a mixture of different chemical components. Human needs food as a resource of energy and for tissue replacement like other animals. Food satisfy appetite and to meet physiological needs for growth, to maintain all body processes and to supply essential energy required for maintaining body temperature and activity.
The six major components of foods are carbohydrates, protein, fats, minerals; vitamins and water. For good health these nutrients are required in correct amounts. The source of much of food consumed by man is territorial agriculture.
Food panicles energy for maintaining body temperature and for doing work, growth and as regulator of life the first requirement, energy is met mainly by intake of carbohydrate and fats.
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These nutrients contain only hydrogen, carbon and oxygen. Carbohydrates are sugars and starches and occur mainly in fruits, cereal, vegetable, nut and milk. Fats are distributed in animals and plants.
These are 20 natural amino acids, 8 of which cannot be synthesized by human body. These amino acids are known as essential amino acids and forms protein.
The source of much of the food consumed by man is terrestrial agriculture. There are two main types of the agriculture: Crop agriculture in which the plant production is harvested for use by mans either directly or after processing and animal agriculture, where a crop from highly manipulated ecosystem is led to domesticated animals.
Ecologically, terrestrial agriculture presents man either as a herbivores or as a third trophic level carnivores. Plants products constitute a 90 percent of world’s agriculture output. 30-40 percent of plant’s net primary productivity can usually be harvested and 70 to 80 percent of such a harvest can be digested by human beings.
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Creals are the staple food. They contain 10 percent protein and high amount of carbohydrates. Wheat corn and rice account for 60 percent of production. The people in every other region survived on net imports. At present time, the human population is increasing faster than its food supply. The productive agriculture land is being destroyed at an alarming rate throughout the world, even as population continues to expand. In order to increase the agriculture produce the “Green revolution” was introduced in some countries in 1966 using high yielded seeds.
The potential yields of new varieties are so spectacular that many people heralded their introduction as the Green Revolution. For e.g. in India and Pakistan massive shipments of Green revolution wheat in the late 1960s raised the wheat harvest between 50 and 60 percentage during a period of two growing season.
Farmer uses manure, straw or dead fish to fertilize their crop. Today mineral and manufactured fertilizers (nitrogen) are used so extensively. Pesticides and chemical substances that are employed in agriculture, forestry and horticulture to combat animal and plant parasites a distinction is made between herbicides, used against weeds, fungicides against fungi, insecticides against insects, acaroids against mites, nematicides against nematodes, rotendicites against rodents, molluscicides against snails and slugs and seed dressings.
Pesticides can be used only in small quantity otherwise they caused damage to health and ecosystem.
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Overgrazing, water logging and salinity also cause problems to agriculture. Terrestrial agriculture system today exhibits a major division into shifting and secondary types. In shifting cultivation, total manipulation of the natural systems is patricides over a limited area but for only a short (1-5 years) period of time.
Thus agriculture path is spatially and temporally enclosed by wild vegetation. Sedimentary cultivation represents the permanent manipulation of an ecosystem: the natural biota are removed and replaced with domesticated plants and animals.
To increased production “Green revolution” was used and ecologists have provided certain solutions for agriculture extension and intensification and have suggested certain new food resources for man.
(a) Extension of agriculture:
Improved machinery, irrigation, better roads, reclamation and transformation to provide greater agriculture area.
(b) Intensifications of agriculture:
Improvement of foods yield from existing cultivated lands. A great capital and management is needed for success by irrigation, flood control, drainage, erosion control, and fertilizers.
New Source of Food
A search for supplementary source of plant and animal proteins is, therefore in progress. Animal proteins are more preferred ones because their amino acid make up is closest to man’s requirement. E.g. Animals flesh, Fungi, Algae, extension of fisheries, aquaculture