Food resources: Environmental sciences Notes, MCQ, Books, PDF Downloads
EVS Notes Unit I Multidisciplinary nature, Natural Resources, Forest resources, Water resources, Mineral resources, Food resources, Energy resources, Land resources, Role of an individual Unit II Introduction structure-function, Forest eco-system; Grassland ecosystem; Desert ecosystem; Aquatic ecosystems Unit III Air pollution, Water pollution, Soil pollution
Food is essential for the growth and development of living organisms. These essential materials are called nutrients and these nutrients are available from a variety of animals and plants. There are thousands of edible plants and animals over the world, out of which only about three dozen types constitute the major food of humans.
The majority of people obtain food from cultivated plants and domesticated animals. Although some food is obtained from oceans and fresh waters, but the great majority of food for the human population is obtained from traditional land-based agriculture of crops and livestock.
It is estimated that out of about 2,50,000 species of plants, only about 3,000 have been tried as agricultural crops. Under the different agro-climatic conditions, 300 are grown for food and only 100 are used on a large scale.
Some species of crops provide food, whereas others provide commercial products like oils, fibres, etc. Raw crops are sometimes converted into valuable edible products by using different techniques for value addition. At the global level, only 20 species of crops are used for food. These, in approximate order of importance, are wheat, rice, corn, potatoes; barley, sweet potatoes, cassavas, soybeans, oats, sorghum, millet, sugarcane, sugar beets, rye, peanuts, field beans, chick-peas, pigeon- peas, bananas and coconuts. Many of them are used directly, whereas others can be used by changing them by using different techniques for enhancing calorific value.
Domesticated animals are an important food source. The major domesticated animals used as food sources by human beings are ‘ruminants’ (e.g. cattle, sheep, goats, camel, reindeer, llama, etc.) Ruminants convert indigestible woody tissue of plants (cellulose) which are earth’s most abundant organic compounds into digestible food products for human consumption. Milk, which is provided by milking animals, is considered to be the complete food. Other domestic animals like sheep, goats, poultry and ducker can be used as meat.
Fish and seafood contribute 17 million metric tonnes of high-quality protein to provide a balanced diet to the world. Presently aquaculture provides only small amounts of world food but its significance is increasing day by day.
World Food Problems
As per estimates by the Food and Agriculture Organization (FAO), about 840 million people remain chronically hungry and out of this 800 million are living in the developing world. In the last decade, it is decreasing at the rate of 2.5 million per year, but at the same time world’s population is increasing. The target of cutting half the number of the world’s chronically hungry and undernourished people by 2015 will be difficult to meet if the present trend continues.
Due to inadequate purchasing power to buy food, it is difficult to fulfil the minimum calorific requirement of the human body per day. A large number of people in India are poor which can be attributed to the equitable distribution of income.
Food insufficiency can be divided into two categories into
under-nourishment and malnourishment.
Both of these insufficiencies are global problems.
The FAO estimates that the average minimum daily caloric intake over the whole world is about 2,500 calories per day. People who receive less than 90% of their minimum dietary intake on a long-term basis are considered undernourished. Those who receive less than 80% of their minimum daily caloric intake requirements are considered ‘seriously’ undernourished.
Children in this category are likely to suffer from stunted growth, mental retardation, and other social and developmental disorders. Therefore, Under-nourishment means a lack of sufficient calories in available food, resulting in little or no ability to move or work.
A person may have excess food but still, diet suffers due to nutritional imbalance or inability to absorb or may have problem utilizing essential nutrients. If we compare the diet of the developed countries with developing countries people in developed countries have processed food which may be deficient in fibre, vitamins and other components whereas the diet of developing countries, maybe lack specific nutrients because they consume less meat, fruits and vegetables due to poor purchasing power.
Malnourishment can be defined as a lack of specific components of food such as proteins, vitamins, or essential chemical elements.
The major problems of malnutrition are:
Marasmus: progressive emaciation caused by lack of protein and calories.
Kwashiorkor: a lack of sufficient protein in the diet which leads to a failure of neural development and therefore learning disabilities.
Anaemia: it is caused by a lack of iron in the diet or an inability to absorb iron from food.
Pellagra: it occurs due to the deficiency of tryptophan and lysine, vitamins in the diet.
Every year, food problems kill as many people as were killed by the atomic bomb dropped on Hiroshima during World War II. This shows that there is a drastic need to increase food production, equitably distribute it and also to control population growth.
Although India is the third-largest producer of staple crops, it is estimated that about 300 million Indians are still undernourished. India has only half as much land as the USA, but it has nearly three times the population to feed. Our food problems are directly related to the population.
The supply of adequate amounts of different nutrients can help to improve malnutrition and its ill effects. Cereals like wheat and rice can supply only carbohydrates which are rich in energy supply, are only a fraction of the nutrition requirements. The cereal diet has to be supplemented with other food that can supply fat, protein and a minor quantity of minerals and vitamins. A balanced diet will help to improve growth and health.
Changes Caused by Agriculture and Overgrazing
For centuries, agriculture is providing inputs to a large number of industries involved in the production, processing and distribution of food. Accordingly, agriculture has a significant effect on the environment. The effects of agriculture on the environment can be classified at local, regional, and global levels. Agriculture also makes an impact on the usage of land generally as follows:
• Soil Erosion
• Depletion of nutrients
• Impact related to high yielding varieties (HYV)
Fertilizer-related problems include micronutrient imbalance, nitrite pollution and eutrophication.
Pesticide-related problems include creating resistance in pests and producing new pests, the death of non-target organisms, and biological magnification.
Some other problems include water logging, salinity problems and others.
The carrying capacity of the land for cattle depends upon the micro climate and soil fertility. If carrying capacity is exceeded then the land is overgrazed. Because of overgrazing, the agricultural land gets affected as follows,
• Reduction in growth and diversity of plant species
• Reduce plant cover leads to increased soil erosion
• Cattle trampling leads to land degradation
Effects of Modern Agriculture
For sustainable production, modern techniques are used to enhance the productivity of different cropping systems under different agro-eco-zones. Adoption of modern agricultural practices has both positive and negative effects on the environment. Effects of modern agriculture are briefly discussed under different heads:
Raindrops bombarding bare soil result in the oldest and still most serious problem of agriculture. The long history of soil erosion and its impact on civilization is one of devastation. Eroded fields record our failure as land stewards.
Adequate rainfall is never guaranteed for the dry land farmer in arid and semiarid regions, and thus irrigation is essential for reliable production. Irrigation ensures sufficient water when needed and also allows farmers to expand their acreage of suitable cropland. In fact, we rely heavily on crops from irrigated lands, with fully one-third of the world’s harvest coming from that 17% of cropland that is under irrigation. Unfortunately, current irrigation practices severely damage the cropland and the aquatic systems from which the water is withdrawn.
Agriculture and the loss of genetic diversity
As modern agriculture converts an ever-increasing portion of the earth’s land surface to monoculture, the genetic and ecological diversity of the planet erodes. Both the conversion of diverse natural ecosystems to new agricultural lands and the narrowing of the genetic diversity of crops contribute to this erosion.
For photosynthesis apart from water, sunshine and CO2, plants need micro and macro nutrients for growth. These nutrients are supplied in the shape of fertilizers. There is a lot of potential to increase food productivity by increasing fertilizer use. On the one hand application of artificial chemical fertilizers increases productivity at a faster rate as compared to organic fertilizers, on the other hand, the application of fertilizers can be a serious problem of pollution and can create a number of problems.
Excessive level of nitrates in groundwater has created problems in developed countries. These are:
a. Accumulated phosphorous as a consequence of the use of phosphoric fertilizer are posing a serious threat as residues in domestic water supply and to the ecology of rivers and other water bodies. Increased levels of phosphates in different water results in eutrophication.
b. Effect of chemical fertilizer is long-term, therefore leading to a net loss of soil organic matter. To control insects, pests, diseases and weeds which are responsible for the reduction in productivity different chemicals are used as insecticides, pesticides and herbicides. Successful control of insects, pests and weeds increases productivity and reduces losses and provides security for harvest and storage.
Applications of these synthetic chemicals have great economic value and at the same time cause a number of serious problems such as:
a. Affects human health which includes acute poisoning and illness caused by higher doses and accidental exposure
b. As long-term effects, causes cancer, birth defects, Parkinson’s disease and other regenerative diseases.
c. Long-term application of pesticides can affect soil fertility.
d. Danger of killing beneficial predators.
e. Pesticides resistance and pest resurgence
High water table or surface flooding can cause water logging problems. Water logging may lead to poor crop productivity due to anaerobic conditions created in the soil. In India, deltas of Ganga, Andaman and Nicobar Islands and some areas of Kerala are prone to frequent water logging.
Adoption of intensive agriculture practices and increased concentration of soluble salts leads to salinity. Due to poor drainage, dissolved salts accumulate on the soil surface and affect soil fertility. Excess concentration of these salts may form a crust on the surface which may be injurious to the plants. The water absorption process is affected and the uptake of nutrients is disturbed. According to an estimate, in India, 7 million hectares of land is saline and the area is showing increasing trends due to the adoption of intensive agriculture practices.
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