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Home Home » Archives for 2018-05-13

Thursday, 17 May 2018

Food Supply

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 Production
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:

  1. 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. 
  2. 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. 
  3. 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;                                        
Produce a high yield 
Have a high nutritive content 
Are resistant to pest and diseases, and 
Will grow successfully in area where they could not grow before. 
In the future, generic engineering techniques may make it possible to have crop strains that have characteristics like ability :
• To fix atmospheric nitrogen or
• To produce chemicals that can prevent them from succumbing to diseases. 
   In temperate countries, selective breeding has produced many livestock breed that are highly productive. 
4. Mechanization : To obtain high yields in farming, mechanization is important. The extent of mechanization depends on the size of the farm. 

Preserving and Storing Food

Most foods spoil if they are not stored properly. Spoilage is due to
• 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.

Drying
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.

Low-temperature Preseevation
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:
•refrigeration
•freezing.

Pasteurization 
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.

Fermentation 
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.

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Tuesday, 15 May 2018

Forest Management

Forest management is the act in which activities in forest are being controlled in an orderly manner. 

Meaning and Importance of Forest
A forest generally refers to any area of land that is covered with trees along with the undergrowth of shrub between the trees.
  1. Forest provides timber for export. 
  2. It provides wood for used planks, furniture, fuel, paper, etc. 
  3. It is a source of medicinal herbs. 
  4. Provides wild fruits and seeds for consumption. 
  5. Forest harbour wild animals which are useful to man as meat. 
  6. Forest cover helps to prevent erosion and serves as wind break. 
Forest has effect on local climatic conditions and helps to check desert encroachment. 
  1. It increases soil fertility through the decomposition of leaves of plants and helps to enhance the growth and activities of soil microbes. 
  2. Source of industrial materials such as dye, resin. 
  3. Provides leaves for packaging e.g I plan its. 
  4. Serves as tourist attraction. 
  5. Serves as source of revenue and employment to people who are involved in lumbering activities.

Some Important Trees and Animals found in Forest


TREES ANIMALS
1. Mahogany (Khaya ivorensis) 1. Elephant (Loxodonta agricana)
2. Iroko (Chlorophora excelsa) 2. Green Monkey (Phacopithecus aethiopicus)
3. African Walnut (Lovoa klaineana) 3. Grass cutter (Thryonomys swinderianus)
4. Obeche (Triplochiton scleroxylon) 4. Antelope (Neotragus spp)
5. Opepe (Sarocephalus diderrichii) 5. Bush fowl (Gallus spp)
6. Pulp wood (Gmelina arborea) 6. Mahogany (Crycetomys gambianus)

Forest Management Practices 
1.) Forest regulations :
These are laws made by government aimed at preserving or conserving forest trees and other forest resources. Such laws helps to regulate the felling of trees for timber (lumbering),  killing of animals in forest reserve etc. 
In Nigeria, some of the forest regulations are :

  • Prohibition of individuals or group of persons from entering Forest reserve to fell trees, hunt, make private farms etc, without permission granted by the appropriate authority;
  • Prohibition of persons from setting fore on forest reserve and bush in general. 
2.) Regeneration
         This is the practice of replacing cut trees in the forest. There are two types of regeneration — natural and artificial regeneration. In natural regeneration, the stumps of cut trees are allowed to regrow to become new trees. Also seeds that are naturally dispersed germinate and grow into new forest trees. This is a cheap way of regenerating forest as it does not involve any cost on the part of the farmer. 
     In artificial regeneration, seeds or seedlings of forest trees are planted to replace cut trees in the forest. This method is expensive in terms of cost and time. 
3. Afforestation
      This involves the planting of trees in an area where there has been no forest previously. It is usually an attempt to artificially establish forest cover in areas where there are no natural forests. This helps to prevent desert encroachment, protect the soil against erosion and serves as wind break. Atmospheric pollution is also reduced while the environment can be beautified through afforestation. Afforestation also brings about all the other benefits that are derived forest 
4. Deforestation
This is the continuous removal of forest stands (trees) without replacing them deforestation could be brought about by :
  • Man's farming activities 
  • Bush fire
  • Over grazing 
  • Road construction 
  • Industrialization 
  • Mining and quarrying 
  • Timber exploitation and fuel wood cutting 
  • Natural disasters 
Deforestation has the following effects on the environment :
  1. Encourages/increases soil erosion
  2. Reduces water percolation
  3. Results in loss of soil nutrients 
  4. Reduces humus content of soil
  5. Reduces the amount of rainfall in the area
  6. Hinders activities of soil micro-organisms
  7. Reduces wild life population in the area
  8. May lead to desertification 
5. Taungya system
This is the growing of both forestry and agricultural crops on the same piece of land at a time. Or the integration of annual cropping with early stages of forest establishment. The growing of agricultural crops continues on the land until the Forest crop closes canopy. 
There are certain conditions that favour, the practice of taungya system, these are ;
  1. Land hunger
  2. Over population 
  3. Government policy 
  4. Unemployment or underemployment 
  5. Low standard of living 
  6. Availability of incentive for additional farming 
  7. The need to remove unwanted trees from the forest. 
Taungya stems allows for the utilization of fertile Forest land for farming by farmers while it assist the foresters in reducing the cost of establishing forest. Farmers have access to free land while more land is brought under forest cover. 
6. Management problems in forestry
Forest management the act of taking care of forest so as to preserve the echo system
  • Bush fire will kills both plant and animal species in the forest. 
  • Incidence of pest and diseases. 
  • Long period of maturity of timber. 
  • Unlined timber exploiters. 
  • Indiscriminate deforestation by farmers and fuel wood users or dealers. 
  • Inadequate forest supervision by Forest personnel. This could also be due to inadequate forestry personnel. 
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