1. A. Soil Formation

Weathering break up the surface of parent rocks into small particles. Air and water enter the spaces between the particles and chemical changes take pace which resut in the production of chemical substances. Bacteria and plant life soon appear. When plant and animal organisms die, they decay and produce a substance called humus. This is very important to so fertility. Bacteria play a vital role into the decomposition of plants and animals remains. The end product of these mechanical, chemical, and biological processes is called soil which is one of the world’s most important natural resources.

B. Composition of Soil

All soil contain mineral matter, organic matter, air, water and living organisms, especially bacteria. If any one of these is seriously reduced in amount, or removed frm a soil, ten the soil deteriorates.

Soil is an important component of the physical environment of many ecosystem. The main components of a typical soild can be divided into two: Organic components and Inorganic components.

Organic Components - include include living organism such as baceteria and fungi which serve as the decomposers;a very important parts of the recycling and decay processes. It also include many invertebrates animal such as insects and worms. Finally, there are many plants or parts and worms. Finally, there are many plants or parts of palnts such as roots and seeds.

Inorganic compoents – Inorganic components include mineral, water and air. Soil particles are form from rock by weathering. The rock is broken into smaller pieces by the action of rain, wind, frost - in some countries, and physical contact between pieces of rocks. There are different sized mineral particles.

Graver – is a soil particles that is bigger than 2mm in diameter.
Sand – is a mineral particle between 2m and 0.02 mm in diameter.
Clay – is a particle less than 0.02 mm in diameter.
Mineral salts- which include soluble salt such as potassium, phosphate and nitrate, are need by plants to enable healthy growth.

Air – All living things in soil need the oxygen in air. Air can be found in the gaps between soil particles.
Water – water in soil is called soil water. Some of this forms a film around individual soil grains. This is not available to plants. This water is called hygdrosocpic water. If the soil grains are very small as they are in clay, then the hygroscopic water content is high. If the grins are large, as they are in sand, then the hygroscopic content is low.

There are three types of soil water they include: 1. Hygroscopic water, 2. Gravity water and 3. Capillary water.

Hygroscopic water is a soil water that form film around individual soil grains. This water is not available to plants.

In permeable soils, water oves downward under gravity and it carries dissolved mineral from the topsoil to the subsoil or even to the weathered parent rock. This movement of water and dissolved mineral is called leaching and the water is called gravity water.

Water also moves upward in a soil by capillary action. This water contains dissolved minerals. It is called cipillary wter.

2. Food and Cash Crops of Liberia

Food crops are crops grown for the primary purpose of comsuming their produce when harvested. Although farmers may sell any excess, but cash generated from the sale of such excess is often use by farmers to purchase other items they need.

Cash Crops on the other hand, are crops grown usually on large scale for the primary purpose of selling thier produce when harvested.

Intiem passed, the major cash crops of liberia was rubber. In fact, Liberia at one time became the World’s largest producer of rubber. Other cash crops grown in Liberia by then include: Oil- palm, cocoa, coffee,Kola nut and sugar cane. These crops wre grown on very small scale by individual farmers around the country. But today, in addition to rubber, oil-palm is now being grown on a very large scale by foreign investors including Sime Darby,a Malysian company, Golden Veroleum, a subsidiary of Singarpore – listed Golden Agri Resources investing through a New York based private equity fund. Other companies that have grabbed land in Liberia for cash crops production include Equatorial Palm-Oil and rubber plantation in Maryland and River Gee counties. Attention is also being given to other cash crops such as cocoa, coffee, and sugar cane. These crops are still not yeat being grown on a large sclae. But increase in individual farmers production of these crops could see an increase in the production of these crops. The major food crops of Liberia include rice, cassava, plantian, and potatoes. Non of these crops is currently being produced on a large scale. The production of these food crops is being done y farmers using cude means of farming the land.

The vast majority of Liberian farmers do not produce enough gain to feed themselves despite devoting the buld of their land labour resources to food production. This is a food security problem that needs to be address. The inability of farmers to produce enough of these food crops to feed the country have left a gain-defecit household that will have to buy the required balances of their food intake from domestic market, using income earned from cash cropping and more generally from non-farm activities.

The Effects of Nonbiodegradable Substances on Soil Fertility

Nonbiodegradable substances are substances such as pesticides, toxic metals, and radioactive residues from neclear power plants. These substances are not easily broken down by natural processes. They are considered nonbiodegradable because they can presist in the environment for hundreds of years.The current debate is over where and how to store toxic, nonbiodegradable wastes. These substances when expose to the land, they could have everlasting effects of living things including plants and animals.

Plants grow in the soil and animals depend on plants for their food. If the soils in which plants are suppose to grow in are contimanated with nonbiodegradable substances, the soil fertility is destroyed. Green plants find it difficult to grow in a non fertile soil.

Humans and other animals that depend on plants for food will also be affected.

Our war on crop diseases caused by insect, fungi, and bacteria have leed human to pollute the environment with sprays, dusts and aerosols. Such chemical poisons are called pesticides. Unfortunately, some valuable insects are destroyed at the same time the harmful ones are killed. Pesticides also soak into soil and wash into the streams with groundwater. There, they poison fish and other aquatic animals.

Insect eating animals. Absorb chemical poisons when they eat contaminated insects. Some of these pesticides contain heavy lead metals. The concentratioin of heavy lead metal build up from animal to animal in a food chain. Soil fertility is very important in the growning of food crops and crops which are necessary for the production of those that we need.

But if the soild that is most needeed for these activities is destroyed due to nonbiodegradable substances, life on earth will soon be difficult to live. Important plants species will be threaten to extinction. This could affect the world’s population including plants, animals and human, which is alreay facing a food crisis.

SOIL CONSERVATION

The word conservatioin means the saving of natural resources.Soil erosion has made millions of hectares of land uproductive. As the World’s population increase year by year, so more and more food has to be produced if famine and diseases are to be eliminated, and if all people are to get an adequate and balance diet. The government of most countries have for a time realised that soil erosion is a great enemy to people, and measures are now being taken to reduce erosion to a minimum and to reclaim land that has already been eroded.

The types of soil conservation include: contour ploughing, terracing, planting of shelter belts and strip cultivationi and crop rotation.

Contour ploughing in contour ploughing, the furrows in which the crops are planted follow the contours. If the furrows go up and down the slopes, gullying is likely to take place.

Terracing Conservation – Steep slopes can be cut into a series of wide steps on which the crops can than be grown. The steps are called terraces. Terracing is very common in those parts of Asia where rice is grown. Terraces are flooded with water during the growing season, with the water passing from one terrace to the one below it. The flooding of terraces is a very good indication of the ability of terraces to prevent soil erosion.

Planting of Shelter belts – Belts of trees are often planted across a flat region which are liable to experience wind erosion. These trees break the force of the wind and thus protect the strips of land between belts from being eroded.

Strip Cultivation and Crop Rotation - other farming method include the cultivation of alternate strips at right angles to the prevailing winds, so that wne one strip os laid bare for plouging, the adecent strip is under grass or is growing a crop. If the wind blows soil off the bare strip, it will be caught and anchored byt he vegetated strip. Crop rotation and the use of fertilizer ensures that the soil remains fertile and does not lost its structure. It will therefore stick together better and be less likely to blow away.

Forest Conservationi – The forests of the world play important role in water and soil conservation. They hold rain water and release it gradually to the soil below and to the streams, that flow that flow tharough them. They provide a protective cover for soil againt the action of the wind and rain. The forest also act as wind breaks reducing wind speeds and checking the erosion of surround land. In addition, forests have enormous effects on climate and provide homes for widelife.

Wildlife Concervation

The term wildlife includes all native plants and animals. The decline in many wildlife popoulations is a direct result of the destruction of habitats. Cities and subrurbs cannot contineu to develop without the wholesome destruction of wildlife.

Wildlife plays an important role in mantaining the balance of various ecosystems. We are threatening their existence by destroying their habitat and reducing their living space by bush burning, damming rivers and drain swamps. We also destroyed wildlife by polluting their environment and hunting them indiscriminatly for their products such as skin, trunk and meat.

Today, many species are in danger of extinction, and people’s activities will be t he major reason for their extinction. Many game laws today are based on ecologically sound conservation practices. A knowledge of the population density and the capacity of the environment to support a species is important. Then controlled hunting, trapping and fishing can maintain the population at a level in balance with the environment. Individual animal will behealthier if they are not in an over crowdedsatuation. Protection of areas in which people are not allowed to kill wildlife should be set aside as parks. Such parks should include intertidal and subtidal seashore areas, lakes, rivers, forests, and many breeding ground for species in danger of extinction.

Oil Conservation

Forssil fuels include coal, oil and natural gas. These are nonrenewable, meaning once use, they cannot be replenish. As the world’s populationi increased, fuel needs rise. The production, mining, and transportation of fuel become a problem. The su0pply of natural fossil fuels is not being renewed. At the same time, energy demands are doubling every ten years. The rate at which fossil fuels is being used, it just a matter of time for the world to runout of this most needed energy resource.

The only sure means of protecting the current World’s supply of fossil fuels is to look for other sources of energy. These might include energy from the sun, from the heat deep in the earth’s crust, from running water, tides, and wind and even from buring barbage. Electrical energy can be produced by damming rivers and running falling water through turbines. Radiation from the sun can be change to electrical energy in solar batteries.

Mineral Consevation

The most important mineral are the atmosphere, soil, water, forest and wildlife,. The first three are non-living component of the ecosystem. Human activities caused their pollution. They can be conserve by anti-pollution measures. Forest and wildlife are parts of the biotic components of the ecosystem. They are greatly affected by the pollution of the biotic environment.

In addition, human beings have been destroying forest, killing wildlife indiscriminately. Mineral such as gold, diamond etc can be conserved by the following ways:

1. Cutting down their wastage
2. Find acceptable altenative or renewable sources of energy
3. Cutting down on the heavy consumption of these non renewable minerals.

The water cycle is very essential to life. Cells are made up largely of water. Chemical reactions essential for life require water. Water serves as a medium for transporting minerals to various parts of organisms. Many organisms live in a watery environment.

Waters occurs on Earth as a liquid or a solid and in the atmosphere as gas. When it rains, some of the water that fall on the Earth’s surface infilatrates the soil, flowing through it as through flow; some flows over the surface as overland flow, some lies on the surface as ponds and lakes and some returns to the atmosphere as water vapour through evaporation and transpiration. Water begins its cycle through the ecosystem, community when plants absorb water through their roots.

Animals drink water or get it directly from the food they consume. As water moves through the ecosystem, plants and animals loss it back to the atmosphere through respiration.
Organism also loss water through excretion. After an organism dies, decompositioni releases water back into the environment.

The Carbon cycle

The two basic life processes involved in carbon-oxygen cycle are respirationi and photosynthesis. Both plants and animals respire. Only green plants carry on photosynthesis.

Carbon is found in the environment as carbondioxide gas (CO2) in the atmosphere and ocean. From the atmosphere, carbondioxide moves to aquatic and terrestrial producers. Produeces use carbon dioxide with water to make sugar. Photosynthesis change these molecules from low to high energy forms. Energy from the sun joins carbondioxide, oxygen and hydrogen from water into energy rich sugars. Organisms obtain carbon when they consume producers or other consumers. Respiration and decay are two processes that usually return carbon to the atmosphere in the gas CO2. Decay sometime occurs in wamps, bogs or other areas that have low amount of oxygen, the carbon can be boundup in a fossil fuel, that fomed overtime by geological processes- carbon also returns to the atmosphere in large amounts as carbondioxide when fossil fuels are burned.

The Nitrogen Cycle

Atmosphere nitrogen makes up nearly 78% of air. Inspite of this abundance however, nitrogen is often a limiting factor in plant growth. Livingthings cannot use nitrogen in the atmosphere form. Lighting and some other bacteria convert atmospheric nitrogen into usable nitrogen containing compound that can be used by living things. Plants take up nitrates made by bacteria and lighting. Plants convert the nitrates into molecules that contain nitrogen containing animal proteins. During digestion, your convert plant proteins and animals proteins to form that combine to make human proteins. Organism return nitrogen to the atmosphere when they die and decay.

The Phosphorus Cycle

Phosphorus, one of the essential elements cycles in two ways. Plants use phosphorus in soil in their body tissues. Animals get phosphours by eating plants. When these animals die, they decompose and phosphus is return to the soil to be use again.This is the short term phosphorus cycle.

Phosphours can also have a long term cycle. Phosphates washed into the sea become incoperated into rock as insoluble compunds. Millions of years later, as the environment changes, the rock containing phosphorus is exposed and the phosphorus can again be made part of the local ecological system.

The Surfur Cycle

The sulfur cycle is the collection of processes by which sulfur moves to and from minerals and living systems. Such biogeochemical cycles are important in geology because they affect many minerals. Biogeochemical cycle are also important for life because sulfur is an essential element, being a constitutent of many proteins cofactors.

Steps of the Sulfur Cycle are:

1. Mineralization of Organic Sulfur into Inorganic forms, such as hydrogen sulfide, elemental sulfur, as well as sulfur minerals.
2. Oxidationo f hydrogen sulfide, sulfide, and elemental sulfur to sulfate.
3. Incorporation sulfide into organic compound.
These are often termed as follows:

Assimlative sulfate reductionin which sulfate is reduce by plants, fungi and various prokaryotes.

Desulfurization in which organic molecules containing sulfur can be desulfurized, produced hydrogen sulfide gas.

Oxidationof hydrogen sulfide produces elemental sulfur. This reaction occurs in photosynthetic green and purple sulfur bacteria and some chemolithrophs. Oxidation of element sulfur by sulfuroxidizers produces sulfate. Dissimilative sulfur reduction in which elemental sulfur can be reduced to hydrogen sulfide. Dissimilative sulfate reduction in which sulfate reducers generate hydrogen sulfide.

Bibliography

1. Madigan M.T. Marino – Brock biology of microorganism 11th edition
2. Biggs, Kapick and Lundgen – Biology, the Dynamics of life
3. Holt, Rinehart and Winston – Modern Biology.
4. Dr. Geepu Nah Tiepoh – Limites of cash crops production in Liberia’s food security strategy
5. R.B. Bunnett and P. Oluatunde Okunrotifu – General Geography in Diagrams for West Africa