Subject: Agricultural Science
Topic: Rangeland and Natural Grazing
Lesson Objectives: At the end of the lesson, learners should be able to:
- State the importance of Rangeland and natural grazing,
- State the characteristics of a good Rangeland,
- Discuss the factors that affect herbage Production in Nigeria,
- Explain how livestocks are managed on a natural grazing,
- State reasons why rangelands are the main source of herbage supply.
Lesson Summary /Discussion
Forage crop refers to grass, legumes and other forms of herbage that are eaten or grazed by especially ruminant farm animals. They may be raised by man in man-made or artificial pastures or could grow naturally in uncultivated pastures.
These uncultivated pastures that are rich in forage legumes, grasses, fodder crops and small trees is referred to as natural grazing or Rangeland. The nomadic cattle rearers in their charactersitics North-South migratory life herd their livestock through the Rangeland of Nigeria. There is material evidence to prove that natural grazings often provide the major source of forage available to the greater majority of livestock owners in Nigeria.
Importance of Rangeland and Natural Grazings
- Major source of herbage in the tropics.
- It could be preserved into hay/sillage especially when cut before flowering.
- Animals under range obtain maximum bodily exercise
- The range provides a variety of forage species so that balanced diet is obtained by out door managed animals.
- Dependence on the Rangeland costs the farmer almost nothing.
- It supplies animal dung to the soil, and this increases soil fertility, infiltration, percolation and water holding capacity.
Limitation of Rangeland
- Trampling breaks up soil surface and destroys soil structure thereby making the soil prone to erosion.
- There is uncontrolled mating
- Animals may be fatigued by distant trekking.
- It exposes the animals to some deadly external parasites such as tsetsefly, to vemins and thieves.
- The Rangeland is prone to devastation by wild fire
- In some localities, absence of some biotypes or forage crop species.
Characteristics Of Good RangelandIn establishing a pasture for the provision of livestock feed especially ruminant the characteristics of the pasture should be considered. Some of the characteristics of the pasture which are very vital include the chemical composition (nutritive value)of the digestibility of the pasture, palatability of the pasture, growth ability of the pasture, and its persistence or resistance to trampling.
Nutritive value of pasture is assessed in terms of energy availability and the content of protein, minerals and vitamins and absence of toxins. New pasture introduction need to be screened for their possible content of harmful or toxic substances. For example, Leucaen leucoccphala has a high content of mimsine which depresses cell division.
A good pasture should be highly digestible. Animal output is first determined by the amount of forage eaten and the proportion digested. Dry matter intake of a good quality pasture is usually about 2.5 – 3% of body weight. Digestibility can be accurately and easily estimated in the laboratory by means of in-vitro technique, in which rumen liquor collected from an animal is used to digest small samples of pasture held at constant temporature.
The grasses and legumes found in a Rangeland must be highly palatable to the animal grazing. Giant star grass-centrosema mixture is well relished by ruminants.
Pastures to be established must have a high yielding ability. The pasture should grow very fast, tall and leafy.
A good pasture should be resistant to trampling by the grazing animals and intense cutting as well as high re-growth potential.
Factors Affecting the level of Herbage production in NigeriaThere are various factors that affect the level of production of herbage in West Africa. Some of these factors are climatic factors, edaphic factors, physiographic factor, burning, land clearing, grazing and other human activities.
i. Climatic factors are wind, rainfall, temperature and humidity
Climate is one of the most important factors which determine the type of rangeland and its botanical composition.
ii. Day length: The length of the day determines whether flowering occurs in grasses. Many tropical plants flower in response to shortening days. It is therefore an important factor in selecting pastures e.g guinea grass, elephant grass, gamba grass for grasses and centrosema, calopogonium, stylosanthes for legumes.
iii. Edaphic or soil factors: The type of soil found in a place determines the type of pastures found there. Some pastures do well on acidic soils and some on alkaline soils. Stylosanthes for example thrives well on acidic soils.
iv. Fire (Burning): Fire induced grassland types are common throughout the tropics. Many woody plants in Africa are killed by fire, and repeated burning leads to a herbaceous cover. The tall rhizomatous grass Imperata cylindrica has become the dominant species on many sloping humid and sub-humid, low fertility lands.
v. Land clearing: Similarly, clearing of land of trees and shrubs also affect the composition of grassland.
vi. Grazing: The increased grazing pressure caused by the introduction of domestic animals has caused very great changes in grassland communities. Some have been destroyed absolutely and others have been improved by skilled manipulation of livestock.
Livestock Management On Natural Grazingi. Choice of Livestock: On unimproved ranges, indigenous livestock are likely to thrive better than exotic breeds. In humid areas, Trypanosome tolerant cattle breeds e.g N’dama and Muturu have to be used. In “high grass” regions, cattle thrive better than sheep while on “short grass” ranges sheep and goats thrive better than cattle. Exotic breeds thrive better in Montane (Highland) areas than the tropical breeds.
ii. Fencing and herding: Fencing of the rangeland is not economically viable in the tropics and herding is the main method of controlling livestock on the ranges. Herding is the main method of controlling livestock on the tropical ranges so that they never graze out all the desirable species, that is, over graze the range.
iii. Provision of shade: Almost all types of livestock need this at certain times of the year. However, it is scarcely provided by the herdsmen in Nigeria.
iv. Provision of water: Efforts should be made to provide adequate supply of water to the livestock at strategic locations. In practice the nomads herd the cattle to the streams, rivers, ponds, etc.
v. Stocking rates: In practice stocking density is too high on range in the dry trophics while it is too low on ranges in the wet trophics. Optimum stocking rate should be permitted on the range so that the vast quantities of dry matter or vegetative cover should neither be wasted nor be allowed to deteriorate.
vi. Use of fertilizers: The use of fertilizers on range forage is likely to be uneconomic and may be adopted only in exceptional cases.
vii. Control of bush/weeds: Chemical and mechanical methods of weed/bush control is uneconomic in the trophics ranges and the only economic method of bush control on Rangeland is burning which is condemned by most foresters and soil conservationists.
Objections raised against bush burning include:a. It wastes organic matter in the soil
b. It exposes the soil surface to the forces of erosion
c. It kills young trees that may grow to serve as shade plants.
d. It destroys fences
e. It encourages the proliferation of fire resistant bush species that may not be good for browse or grazing.
Reasons Why Rangelands Are The Main Source Of Supply Of Herbage In The Trophics:Many farmers in the trophics depend on the natural grazings rather than on the cultivated pastures for their supply of herbage for the following reasons:
i. Irrigation is required for the cultivation of forage in the trophics and many farmers cannot afford this. Again, yields do not usually justify the use of irrigation.
ii. The cultivation of pastures demand expenditure and farmers are least prepared to invest in crops that have no direct cash returns.
iii. Improvement of forage productivity is needless unless superior type of livestock are kept to use the forage species so I’m proved.
iv. Even if farmers decide to cultivate forage, they lack the knowledge of the suitable species to cultivate and the methods of establishment and management.
v. The peasant farmers do not have high degree of managerial ability required for the cultivation and use of the forage.
vi. In many tropical regions, the increasing population pressure is such that all available land is used for the production of crops that have direct food value.
Done studying? See previous lessons in Agricultural Science
- What the importance of Rangeland and natural grazing?
- What the characteristics of a good Rangeland?
- Discuss the factors that affect herbage Production in Nigeria.
- Explain how livestocks are managed on a natural grazing.
- State reasons why rangelands are the main source of herbage supply.
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