Pastures Crops And ESTABLISHMENT AND MANAGEMENT OF PASTURE





Any area which is used for grazing farm animals is considered as pasture or grassland. The composition of pasture varies, however, depending on the climate and soil of any given area and the presence of certain types of grass and other plants which provide '"suitable food for animals. These are often referred to as herbage; when grasses and other plants are cut they then become hay. If placed in containers or silos which prevent them from becoming completely decomposed, but which allow certain chemical and biological changes to take place, then the material is referred to as silage.

The term forage crops is also used to describe fresh plant material, made up of both grasses and herbage plants, on which animals can graze.



NATURAL PASTURE OR GRASSLANDS


Many natural pastures are established on soils of low fertility and the grasses and herbage which grass  on these soils will have a correspondingly low nutritional value. They are often coarse and fibrous and the number of animals per hectare which can be fed on them is therefore limited. Their composition also depends on the level of grazing or other treatment, such as burning, to which they have been subjected.

Over-grazing will lead to a reduction in the numbers of certain types of grass and herbage plants, some are also sensitive to burning and these plants will gradually disappear from a natural pasture. As a result, the plants and grasses which are resistant to these treatments will increase in numbers and, since these types of resistant plants are often low in nutritional value and may even be unpalatable, the pasture will even tually become unsuitable for grazing. In areas of low rainfall, also, pastures may be dominated by grasses which are drought resistant and which are only palatable to animals in the young state as they become older they become coarse and fibrous. During rainfall periods, however, this type of grassland can feed a reasonable number of animals but since this period is often of a verylimited duration, its usefulness is marginal.


In many natural grassland areas, the danger of invasion by shrubs are trees is a constant threat to the composition of the vegetation cover. When over animal, much of this material is high in protein and minerals. One advantage of this is that many trees and shrubs produce leaves before the rains and also retain their nutritive value into the dry season and it is possible that the feeding value of these leaves may be greater than that of dry season grass.

However, the presence of more trees and shrubs than are required to provide shade is undesirable, due to the reduction in herb and grass cover and the possibility of erosion.Burning is often the only method available to control the spread of bush growth, but this should be carefully controlled and should be done at a period when the damage to the grass cover will be minimal. The best time to burn is usually at the end of the dry season when the grass is dormant but when the trees and shrubs have begun to produce new leaves. In this condition, they are most likely to be severely damaged.

In some areas, burning is carried out after the first few showers of rain. Since a fierce fire is required for controlling tree and shrub growth, it is preferable to rest areas from grazing for some time before the burning begins to allow for the accumulation of a good quantity of dry grass. For effective bush control, repeated burning, possibly once in four years, will be necessary. The practice of mixed grazing is sometimes used to retain the nutritional value and variety of species in a pasture, Different animals have different grazing habits and cattle and goats are a good combination.

The goats tend to browse mainly on bushes and small trees rather than on the lower parts of grasses.


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ESTABLISHMENT AND MANAGEMENT OF  PASTURES


The replacement of natural pastures by either high yielding and nutritious grasses or mixtures of these grasses with legumes is often a desirable objective but difficult to achieve. These cultivated pastures, of a fairly short-term nature, are termed 'leys'. The main requirement is a favourable rainfall since many of the most suitable grasses for grazing are not able to survive an extended dry season such as exists in many savanna areas. In areas which are marginally suitable, the yield of introduced grasses may be little higher than that given by more drought-resistant but less nutritiousbnatural pastures.


The establishment of cultivated pastures is also dependent on the availability of suitable land; the land tenure system may also make farmers reluctant to invest labour in establishing permanent pastures or even temporary leys, if they have no secure tenure over their farms. One of the main problems is that the poor productive capacity of the stock may make such an undertaking uncconomic, since the increase in income from grazing poor quality stock on a cultivated pasture may be very limited. Where a higher grade of animal is kept, however, the establishment of permanent pasture or temporary leys is an economic undertaking.


The main factors to be considered in the selection of herbage species for cultivated pastures are as follows.

1. Rapid establishment, with a minimum of preparation, is essential. The usual way of achieving this is by broadcasting seed but some species of tropical grass do not readily set seed in some ecological areas and are more easily propagated by vegetative means such as by stem cuttings, pieces of rhizome or stolons.

2. High-yiclding selections should be established which are also palatable to animals, vigorous in growth and producing a high proportion of leaf.

3. They should be resistant to regular grazing and not die out during the dry season.

The practical aspects of preparation of a pasture begin with the soil preparation. Cultivating or ploughing in the dry season is preferable so that any weeds which persist can be controlled by subsequent operations. A fairly fine tilt is required if seed is to be sown, otherwise, for planting rhizomes or cuttings, a rougher surface may be left. Fertilisers should be applied and mixed with the surface layer of soil, if there is evidence that the land is deficient in nutrients.


For soils lacking in nitrogen and organic material, a cover crop may be sown during the rains and buried during the dry season. Sowing or planting is undertaken at the beginning of the rains, preferably in rows or drills from 15-45 cm apart. This has the advantage that, with the use of combine drills, fertiliser can be applied with the seed. In general, a shallow depth of sowing is required. The seed may also be broadcast by hand, if drilling equipment is not available. It is important that the germination percentage of the grass is known since many tropical grasses have a low viability, particularly if  stored for some time before sowing. Hand planting of rhizomes or cuttings may be carried out by using a hoe, or in the furrows made by a plough or cultivator.


MANAGEMENT OF PASTURE 

If the seeds or plants have been established in rows, any unwanted weeds may be removed by cultivation or, possibly, by using herbicides.

Grazing may begin when the seedlings or plants are well-esteblished, this will firm the soil surface and encourage some grasses to tiller and others to root from runners. The type of grass and the vigour of growth will determine the time from which grazing should begin, but if allowed too Carly, there will be a danger that the more palatable grasses will be over-grazed, leaving undesirable weeds and grasses to become dominant in the pasture.

In order to be able to keep a more or less constant number of animals throughout the dry and wet season, care should be taken to use some of the grass grazing occurs, therefore, the possibility of the fairly rapid establishment of trees and shrubs is a very real one; there is also an increased risk of erosion occurring and a possible increase in population of the tsetse fly. 

The main objectives of management of natural pastures may therefore be summarised as follows.

¡) The provision of a supply of good herbage for grazing for as long a period as possible in order to maintain the maximum number of animals.

ii) To use the herbage when it is in a condition to supply a high yield, combined with a good level of nutrition.

iii) To maintain pastures in good condition by encouraging the growth of the best species and obtaining an adequate ground cover against erosion.


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MAINTAINING THE VIGOUR OF THE HERBAGE


This can be done by keeping the number of animals grazed to the number which will not cause overgrazing i.e. adjusting the carrying capacity or stocking rates. This will reduce the tendency of animals to graze only on the more succulent and often tallergrowing grasses which encourages the growth of more prostrate but less nutritious plants. Animals should not be allowed to graze too soon after the plants begin to grow again during the first rains following a dry season and the pasture should also be rested during the growing season in order that the root reserves of the herbage plants can recover. The pasture should, preferably, be rested at a different time each year, in order to discourage the growth of undesirable species.

The nutritional value of many grasses reduces rapidly with age, and, in general, as grasses mature, their protein, phosphate and potash contents fall while the fibrous content increases. In the dry season, the phosphate content of dry herbage may be very low; the fall in protein content is also often accompanied by a reduction in digestibility and the total protein content of many grasses may be less than 10% by the flowering stage. It is therefore preferable to graze animals on grasses at a moderately young stage to achieve a compromise between feeding value and total yield.

The trees and shrubs which are often present in natural pastures are eaten by many types of domestic for hay or silage in the wet season, so that it can supplement the reduced grazing available during the dry season.

Rotational grazing is very desirable where the land is available. This involves the use of fences or hedges to divide the land into fields so that the animals can be moved from one pasture to another in order to allow fields to recover from intensive grazing. This also makes it possible to use some fields for hay or silage during the wet season.

Fertiliser application will depend on the fertility of the soil but, in general, most pastures will respond to phosphate at sowing or planting time. Nitrogen is, however, generally required since although the dung and urine from the stock is returned to the soil, not all of the nitrogen contained in these residues is available to the grass plants; a significant amount may be lost as ammonia as well as the proportion lost by leaching during the wet season.

Dressings of a fertiliser such as sulphate of ammonia should be made two or the times during the growing season, preferably immediately after grazing. The amount applied will depend on the fertility of the soil and its structure.


TYPES OF PASTURE GRASSES

The following grasses have been found useful for the establishment of pastures in West Africa.

1 .Northern gamba (Andropogon gayanus)

This can be propagated from seed, and has very variable leaf production. It is a hairy, perennial grass, reaching 3.0-3.5 m on fertile soils but normally 1-3 m high. It is a fairly drought-resistant grass and has good palatability. Suitable for grazing.

2. Cenchrus ciliaris

This species has a spreading habit, with thin stems and fine leaves. It is a perennial grass, useful in pastures, and grows to 1 m in height. Palatability is average, with a high dry matter yield.

3. Giant Star grass (Cynodon plectostachyon)

This is a creeping perennial grass which forms rhizomes. This habit encourages a rapid spread of the grass, forming a good pasture.

4. Rhodes grass (Chloris gayana)

There are many selections of this widely grown tropical grass which may vary in habit from creeping to upright and leafy. Seeds are produced and establishment is rarely difficult.

5. Pangola grass (Digitaria decumbens)

This is a low-growing, leafy grass, high in nutrient value. It is propagated by cuttings and forms a good pasture, particularly in high rainfall areas. It is suitable for low altitudes.

Pastures Crops And ESTABLISHMENT AND MANAGEMENT OF PASTURE Pastures Crops And ESTABLISHMENT AND MANAGEMENT OF PASTURE Reviewed by Legit Mentor on December 16, 2021 Rating: 5

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