The quest for improved growth and high yield of animals had made it possible for increased agricultural practices aimed at achieving these results;in animal production in Rivers State and other parts of Nigeria.
Meaning of Rangeland
In traditional system of animal production, nomadic herdsmen normally trek a very long distance with their animals in search of food and water. This primitive system often lead to poor animal health and low quality of the animal products as well as low resistance to pests and diseases due to the poor vigour of these animals which makes them prone to pathogenic infections.
In modern system, the animals are confined to large hectares of land which are fenced and cultivated with good forage crops. Thus, the important factors such as high soil fertility, adequate rainfall, optimum sunshine, good topography, good drainage and good soil texture and structure are necessary for the maximum growth of forage crops.
A large area of land cultivated with forage crops, fodder crops, browses, and herbage, which are mainly used for livestock feed is known as rangeland. The rangeland can also consist of uncultivated or natural forage crops.
Rangeland management is defined as the cumulative practices aimed at optimum maintenance of rangeland towards improved yields of pasture or forage crops over a long period to ensure constant food supply to livestock in a rangeland. Rangeland improvement on the other hand involves the method aimed towards enhancing the improved qualities of the crops cultivated in the rangeland.
Types of Rangeland Pasture
There are two major types of rangeland pastures, namely,
– Natural and
– Traditional rangeland pastures
The Natural rangeland pasture is the natural grassland that consists of grasses, legumes, herbs, shrubs and trees that are growing naturally in a particular area.
Browses are the plants that are not classified as neither grasses nor legumes which also grow in the same areas with the grasses and legumes as shrubs. These intermediate plants are used mainly as roughages for the feeding of goats. It is mostly goats that browse. Cattle and sheep mainly graze.
The major difference between the natural and artificial range land or pasture is that in the former, the animals tend to trek a long way in search of food thereby waste a lot of energy and thus lead to poor nutritional intake. Whereas in the latter, the animals easily graze in the portion of the rangeland that is close to the paddock where they are kept. This aspect thus promotes the improved health of the animal due to high level of nutrients available from the quality forage to the animals for metabolism in their body.
The production of the animals in a natural rangeland where the forage crops are scattered at distant portions of the range is low compared with that of animals that are kept in paddocks and allowed to graze on distinct portions of rangeland at a particular time. Animals on improved rangeland are more resistant to pathogenic attacks for over a long period due to their improved body systems and nutritional intake which leads to healthy growth and yields of the animals during production.
Characteristics of a good pasture
(i) High palatability: A good pasture of forage crops that is meant for grazing animals such as sheep, goats and cattle must be palatable for these animals to graze upon. It must be fresh and not dry.
(ii) High nutritive value: A good pasture must be of high nutritive value for the animals to derive nutrients that can promote their growth and productivity. A good pasture normally contains little amount of water.
(iii) High digestibility: A good pasture that is grazed upon by animals must be of high digestibility, that is, it must be easily digestible in the alimentary canal of these animals in order to supply the needed energy, proteins, vitamins, etc., needed for the proper growth of the animals.
(iv) High leaf to stem ration: A good pasture must as a matter of fact have a high leaf to stem ration to facilitate the maximum supply of nutrients to animals, high leaf stem ration in the pasture will increase availability of food to the animals and reduce the problem that may be caused by the complete grazing of the grasses and legumes in a rangeland within a short period.
(v) High resistance to trampling: A good pasture cultivated in a rangeland must have a high resistance to trampling by animals in order to ensure constant growth and supply of nutrients to animals.
Importance of Rangeland
(i) It serves as a source of food to livestock (ruminants).
(ii) It facilitates constant supply of balanced diets to animals.
(iii) It ensures the optimum exercises by animals.
(iv) Legumes in the rangeland promote symbiotic nitrogen fixation in the soil. This is facilitated by rhizobium in the root nodules.
(v) It promotes the uniform growth of grasses and legumes. These can be cut in their vegetative stage to be preserved unfermented (hay), or. fermented (silage).
(vi) The decay of dead plants lead to high soil nutrients.
Common Grasses and Legumes in a Rangeland
Methods of Rangeland Management
The methods of rangeland management include; good irrigation schedule, rotational grazing, fertiliser application, rouging, tillage, weed control, mulching, liming reseeding or replacement and thinning, manuring and good drainage system.
(i) Good irrigation schedule: A good irrigation schedule which is practiced in rangeland helps to maintain the soil moisture for optimum growth of pastures and thereby prevent the incidence of drought in the parcel of land. This irrigation is carried out regularly to promote the high palatability, high resistance to pests and diseases which are characteristics of good pasture. Rangeland should be irrigated during the dry season. This ensures the supply of palatable and nutritive grasses and legumes through out the year.
(ii) Rotational grazing: The optimum maintenance of a rangeland is attainable through rotational grazing of animals in the partitioned fields. This is practised due to the need to avoid the build up of livestock pests, obtain uniform quality of herbage, persistence of desired species, and breaking the life-cycle of some pests. These are the reason for preferring rotational grazing to continuous grazing in cultivated rangeland. In addition, continuous grazing of animals on the rangeland, leads to negative effects on the soil which include the depletion of soil nutrients, exposure of soil to erosion, destruction of soil structure, increase in soil acidity (that is reduction in the soil pH), reduced rate of water percolation, reduced soil texture, depletion of sandy-loam into clay soil which retains the greatest amount of water thus causing water logging due to its light, low capillarity, little pore spaces (i.e. Iow porosity), hardens and cracks when dry, and high plasticity. Rotational grazing leads to avoidance of overgrazing of animals on pastures in a rangeland.
(iii) Fertiliser application: The application of fertilisers at the appropriate time to the pastures on a rangeland promotes the growth and improves quality of the pastures. Pastures normally consist of forage (grasses and legumes). Grasses supply mostly energy to the livestock. Examples of grasses are lmperata cylindrical (Spear grass), Panicum maximum (Guinea grass), Pennisetum purpureum (Elephant grass). Legumes supply mostly proteins to the livestock. Examples of leguminuous crops are Stylosanthes gracilis, Pueraria pubesceus, Calopogonium mucunoides. The supply of fertilisers such as ammonium nitrate and superphosphate; promotes growth of leguminous crops in a rangeland.
(iv) Rouging: Rouging of pasture in a rangeland is also one of the methods of rangeland management. Rouging is a process where arable crops are alternated with cultivated pasture to meet the nutrient requirements and bridge the gap of shortage in pasture supply to the animals prior to the maturity of the pasture. Rouging can be done with early maturing of arable crops, forage and fodder crops. The main difference between forage and fodder crops is that forage crops are grazed while the fodder crops are fed. Silage can also be fed to the animals. Silage is a fermented pasture forage crops and is a nutritious source of food for livestock.
(v) Optimum tillage: Optimum tillage is carried out in a rangeland to loosen the hard pans of soil to allow the penetration of roots of pasture grasses and legume to anchor very well and prevent the effect of erosion on the soil. Optimum tillage leads to high yields of cultivated pasture in a rangeland.
(vi) Weed control: The regular weeding of a rangeland helps to reduce the competition for nutrients between pasture forage crops and the unwanted plants that grow along with these cultivated pasture. Weeding also helps to reduce the persistence of pests in a rangeland. Some pests have a drastic effect on pasture due to the presence of certain weeds that are hosts of infection. Weeding is of major importance in rangeland management because it leads to improved soil aeration.
(vii) Mulching: The regular mulching of the soil in a rangeland promotes increased fertility due to the rapid decomposition of plant leaves dogged into the soil to facilitate high humus content of the soil. Mulching helps to replenish the depleted nutrients from the soil as a result of continual utilisation of the forage nutrients by grazing animals. Mulching also helps to improve soil structure and reduces the rate of evaporation of moisture from the soil.
(viii) Liming: Liming is an aspect of rangeland management method which involves the adding of calcium carbonate, calcium oxide, or sulphate to the soil to neutralise the acidity of the soil. Liming helps to maintain the soil pH at its optimum level. The regular liming of acidic soil leads to high yields of grasses and legumes in a rangeland. Excessive presence of hydrogen in the soil causes increase in soil acidity and thus leads to exposure of the soil to erosion activities and poor fertility of the soil due to the poor use of animal dung which is an organic manure. Examples of liming substances include limestone CaCO3; quicklime Cao; slaked lime Ca(OH)2; Gypsum CaSO4, and Dolomite CaCO3,. MgCO3.
(ix) Re-seeding: The cultivation of grasses and leguminous crops in a rangeland tends to show some spaces that tend to be filled by the crops and the vacuum is sown with seedlings to promote the optimum use of the hectares of land. Therefore, the practice of supplying additional seedlings to the unfilled spaces is what is referred to as re-seeding. This method of rangeland management helps to facilitate greater supply of pasture to livestock. In re-seeding, the same species of crops are sown into the empty spaces in the field.
(x) Thinning: There is normally a practice where excessive growth of plant stands occur in a rangeland. This tends to give rise to overcrowding, which can lead to the build-up of pests that causes infection. Therefore, thinning is carried out to prevent over crowdedness of the pasture grasses and legumes in a rangeland. It involves the distinct removal of extra seedlings or plant stands from the soil to avoid excessive competition for nutrients between the forage crops at a particular time.
(xi) Good drainage system: A good drainage system is normally practiced in a rangeland to promote high infiltration rate and percolation, thereby reducing run-off and soil erosion. The drainage system involves the construction of channels which allow flow of water that could have caused water logging in the soil.
Methods of Rangeland Improvement
The methods of rangeland improvement include:
(i) Avoidance of Overgrazing: Overgrazing by animals in a rangeland is to be strictly avoided in order to make the soil least prone to soil erosion. The over-grazing by animals in a rangeland leads to destruction of the soil structure, porosity and soil consistence. The relative size of different soil particles is known as soil consistence. Therefore, rotational grazing is preferred to continuous grazing. The latter leads to reduction in the organic matter in the soil. The over-grazing by animals also leads to the depletion of soil nutrients.
(ii) Controlled burning: The excessive loss of nutrients from the soil is usually reduced by controlled burning. This provides ash which contains potassium as a macro-nutrient needed for proper growth of forage crops in a rangeland. It also helps to kill the toxic weeds that are competing for nutrients and injurious to the forage crops. The incidence of certain pathogenic infections caused by disease – causing agents or pathogens, is also minimised. The practice of controlled burning helps to enhance rapid regeneration of forages and it is normally done at least once a year to get rid of over-mature grasses and legumes.
(iii) Maintenance of balance in legume and grass mixtures: This is carried out in a rangeland using legumes such as pueraria, centrosema, stylosanthes and calopogonium spp. and these are normally sown in an area where they are not cultivated. Grasses are also cultivated in areas where such are not available. The maintenance of the established forage (grasses and legumes) mixture ensures the regular supply of the nutrients to the animals.
(iv) Paddocking: Paddocking of animals in a rangeland helps to prevent the uncontrolled damage of forage crops due to the incessant trampling by animals. The animals are kept in confined paddocks. The young animals have a specially prepared paddock meant for food supplement through creep grazing while the older animals have their paddocks. In this way, reserved areas ungrazed become greatly reserved for future use and this helps to prevent the shortage of forage crops in a rangeland. Paddocking facilitates break in life-cycle of some pests within the fenced area of the rangeland.
(v) Effective pest control: The incidence of pest outbreak in a rangeland is remedied using pesticides that effectively kill some or all of these pests, thereby improving the vigour of forage crops. Good pest control practice also helps to reduce the pace of disease spread.
(vi) Weed control: Weed control in a rangeland leads to minimum competition between unwanted plants that grow in the area where forage crops or pasture are cultivated. It is usually carried out by spraying selective herbicides that are specific to certain weeds. For example, sima zinc, linuron paraguat, aminotriazole sime sine and inuron act on the root of weeds. Dalapon should be avoided because it causes damage to grasses such as guinea grass and elephant grass, which are valuable sources of nutrient to grazing animals in a rangeland.
Weeds control in a rangeland can also be effected manually through clearing, burning, uprooting and burying the weeds to add organic matter to the soil. Weeding also helps to ensure adequate supply of nutrients to the soil, which promotes the growth of forages in a rangeland.