Providing food for an ever increasing human population is one of the foremost concerns today. To do this, we have to study the factors that affect our food supply. These factors are
• food production,
• food preservation and storage,
• food wastage.
Food for humans comes from both crops and livestock. Growing crops is a more efficient way of producing food than rearing livestock.
Food production needs arable land that is land suitable for agriculture. It is increased by improving agricultural yields.
Land for Cultivation
Since the later part of the nineteenth century, land under agriculture has been decreasing. This was due to urbanization and industrialization. More and more land was taken away from cultivation and used for putting up factories, offices, houses, roads and highways. To increase food production, we have to;
1. Keep the land that is presently under cultivation, and not take it away for other purposes;
2. Maintain soil fertility of the land under cultivation by manuring, adding chemical fertilizer, practicing crop rotation and preventing soil erosion;
3. Convert land that is not fit for crop cultivation into fertile land.
Non-productive desert land can be converted to fertile fields by irrigation. This has been done successfully in certain regions of south-western USA. However, it is not easy to irrigate desert land as the soil water dries up fast under desert conditions. This may eventually make the upper layers of soil salty. Many desert soils are usually shallow, with an underlying layer of rickm
Much of the world’s land is covered with hills and mountains. Some of these slopes can be used for cultivation. Terracing and cover crop planting have to be done to prevent soil erosion on slopes.
Some land for crop cultivation can be obtained by clearing tropical jungles and forests. Such land has a very poor humus content, therefore it has to be managed carefully to improve and maintain it fertility.
Improving Agricultural Yields
Crop yields and livestock productivity have been greatly increased by the following methods:
- Soil fertility and fertilizers : Maintaining the fertility of the land ensures a high level of crop production. It is archived mainly through the use of organic manure, artificial fertilizers and rotation of crops.
- Pesticides and Protective Chemicals : Pests, parasites and diseases cause poor agricultural yields in the topics. By using pesticides, vaccines and other protective chemicals, farmers have greatly improved their crop yields and livestock productivity.
- Improved crop and livestock breads : In the 1960s, plant readers or geneticists began the ‘green revolution’. Through selective breeding they developed a new strains of crop plants that have high yields. For example, the ‘IR-8’ and ‘IR-5’ dwarf rice strains produce twice as much rice grains per plant as the normal strains. High yield crop strains have improved food production in many developing countries. However, their cultivation requires machinery and large amount of energy, fertilizer and pesticide — materials that are short in supply in the topics and subtropics. Research stations too have to be set up to teach farmers how to cultivate the new crop strains. In spite of these problems, increasing the world’s food supply depends largely on producing new strains of plants that;
Preserving and Storing Food
• loss of water
• chemical changes as a result of oxidation and enzymes action
• growth of spoilage micro-organisms such as bacteria and fungi which cause decomposition.
In the past, people preserved food by storing it in cool places and by drying, smoking, salting, curing, fermenting and pickling. Today we still preserve food by these methods as well as by canning, freezing, adding chemicals and irradiation. All food preservation methods try to prevent the enzymes in food from working and slow or stop the growth of spoilage micro-organisms.
Cereal are preserved by drying. In many parts of the tropics, this is still done by spreading the grains on mats under the sun and starring the grains from time to time. Modern methods use hot air, direct heat and vacuum to dry food.
Meat, fish, eggs, milk, legumes, vegetables and fruits are preserved by drying.
Drying concentrates the nutrients in food and reduces it water content. This stops the enzymes in dried foods from working and prevents most spoilage micro-organisms from growing on them. Drying also reduces the size and mass off the foods, making them easier to package, transport and store.
Dried foods like cereals must be stored in dry, low humidity places which are fumigated and sealed from pests. Dried eggs, meats, milk and vegetables are packed in aluminum, tin or plastic containers. Drying agents are also included with certain foods when they are packed.
At low temperatures, all life’s processes slow down. Thus, the respiratory rate of fresh fruits, vegetables and seeds slows down, enabling them to last longer; the growth of spoilage micro-organisms also slow down. There are two main low temperature preservation methods:
Micro-organisms cause milk to become sour very quickly, especially in the tropics. To prevent this, Milk is pasteurized by heating to 72°C for 15 seconds and cooling rapidly. This destroys most of the microorganisms, thereby allowing it to ‘keep’ for a longer time.
In fermentation, certain substances in food undergo chemical changes which affect it flavor, odor and texture. Fermentation is carried out by microorganisms under special conditions. The process is often combined with salting. Fruits and vegetables are preserved by this process.
On addition, food substance that contains poisonous ingredients are first subjected to fermentation so as to remove the poisonous substance before preservation. For example, cassava is a staple food in West Africa where it is produced in large quantities. Cassava contains a poisonous substance called Cyanide. This dangerous substance is removed by fermentation for three or four days. Drying and smoking methods are then applied for preservation of the cassava.
Fermentation has alcohol, carbon dioxide and small energy as by-product. In palm wine, fermentation produces alcohol which helps to preserve palm wine from bacterial infection.
Furthermore, tobacco and tea leave are preserved by fermentation through curring.
Preventing Wastage of Food
An important method of increasing the world’s food supplies is to cut down wastage at all stages of food production and storage.
• Manure and Fertilizer : Farmyard manure is wasted instead of being used to fertilize soil and improve it crumb structures. Many farmers also do not know how to apply artificial fertilizer in the correct amount and by the appropriate methods. This waste alot of expensive fertilizers, lower crop yields and upset the ecosystem.
• Harvesting : In the tropics, primitive harvesting and winnowing methods cause considerable crop losses in the field. Careless harvesting of root crops and vegetables causes damage. Damaged crops do not store well and so are wasted.
• Storage : Enormous amount of food are wasted during storage and transport. In the case of cereals, improper drying of grains and storage pest such as rats and weevils cause a lot wastage.