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These crops are grown in cultivated pastures for cutting to produce hay or silage as food for animals kept in stalls, particularly during the dry season. Some fodder grasses can also be grazed but, in general, crops which make good fodder are not suitable for grazing, giving low yields and being generally of too coarse a texture.
They frequently have a tufted habit, which is not a useful characteristic in a grass used for grazing.
Legumes and mixtures of grasses and legumes are also grown for fodder but crops of legumes are normally grown hay. In areas where there may be a pronounced dry season, fodder crops can be very valuable since they can be grown during the wet season and cut for hay or silage to use later in the year when fresh grass is scarce. Some fodder crops, after cutting, can also be used, for a limited period, for grazing.
In humid areas, fodder crops can be extremely useful, particularly where the local grasses are unsuitable for grazing and where grazing areas are also in pure stands for cutting and use as limited. In these areas, cattle are often grazed in fallow rice fields, but the nutritional value of the stubble and weeds is low. The use of fodder crops in such areas is therefore preferable.
ESTABLISHMENT OF FODDER GRASSES
Most species of fodder grass are propagated vegetatively, by planting pieces of rhizome or root stock but some can be established from seed.
They are usually planted or sown in rows so that weeds can be controlled during the early stages. The spacing adopted will vary with the soil and climatic conditions but most grasses should be planted at 60-90 cm between rows, with 40-60 cm between plants in the row. Closer planting may be an advantage, in some areas, since an early covering of the soil will reduce weed growth.
CUTTING AND THE EFFECT ON YIELD
The regularity of cutting will depend on the need to balance total yield against palatability and nutrient value and this will also vary with the grass species grown and the rainfall. The intervals between cuts should be longer in the dry season, to encourage regrowth; at this season both the dry matter content and the protein content of most grasses will rise. The amount of fodder required in the dry season, therefore,may be less than that provided in the wet season, for a maintenance ration.
Grass which is cut too often will become weakened and the rate of regrowth will be reduced. The ultimate result is a lowering of yield and the possible dying out of a number of the root stocks. Six to ten weeks is generally regarded as suitable although an earlier cutting period may give higher protein yields, while later cutting gives the highest yield of carbohydrate and total nutrients. Cutting at a height of 9-10 cm from ground level is suitable for most grasses.
Established fodder grasses should be given applications of nitrogen to stimulate growth and maintain the protein content of the leaves and 4-6 dressings per annum may be required in high rainfall areas.
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PREVENTION OF CROP PESTS & CONTROL MEASURES
CHARACTERISTICS OF SELECTED FODDER GRASSES
1 Guinea grass (Panicum maximum)
There are two main types of this grass, both can be used for cutting as fodder but are not very suitable for grazing. They can be propagated from either seed or division of the rootstock. They are palatable and leafy.
2 Elephant grass, Napier grass (Pennisetum purpureum)
A tall-growing grass, reaching 2-4 m in height. A good leaf-producing, palatable fodder grass but of limited grazing value due to the strength and fibrous nature of the stems. It can be propagated from cuttings or division of the rootstock. It requires cutting every 6-8 weeks in the wet season. Elephant grass is suitable for cultivation at elevations up to 2 000 m. Some selections are unsuitable due to excessive hairiness.
3 Guatemala grass (Tripsacum laxum)
This is lower-yielding than elephant grass but is more palatable and leafy and also maintains a reasonable yield during the dry season. It should be cut at intervals of 8-10 weeks at a height of 20-30 cm from ground level. This grass is not suitable for grazing since it tends to become uprooted.
4 Setaria sphacelata
A leafy and succulent grass with a fairly high protein content. It requires fairly fertile soil but grows well at elevations up to 2 000 m. It is normally established from seed.
Legumes used as fodder crops
The following leguminous crops are used in West Africa for cutting and using as hay or silage.
1 Centrosema pubescens
A perennial legume, tolerant to a wide range of soils and climatic conditions, but grows well in the higher rainfall areas. Established from seed and rather slow in the early stages of growth. Palatable to cattle and sheep and forms a good cover. It has been partially successful in combination with some grasses.
2 Kudzu (Pueraria phaseoloides)
Widely grown as a cover and fodder crop in many parts of West Africa, rapid in growth from the seedling stage and forms a dense cover as a pure stand.
Very vigorous in high rainfall areas, but does not regenerate rapidly after cutting. Palatable to cattle.
3 Stylosanthes gracilis
Often referred to as 'Stylo', a very dense cover crop which can be propagated by seeds and cuttings.
Tolerant to a wide range of conditions but relatively slow-growing in the early stages and does not recover rapidly from grazing or cutting.
4 Cowpea (Vigna sinensis)
An excellent cover and fodder crop. Some new cultivars are tolerant to a wide range of climatic and soil conditions and are highly nutritious as well as producing high yields. Good palatability.
Soya bean (Glycine max), and Florida Velvet Bean (Stizolobium decringianum) are also grown for fodder, but are more suited to the savanna than the high rainfall areas.
Leguminous plants used in grass-legume
mixtures Leguminous plants which are used as cover crops have already been referred to in Chapter 2. When used for feeding animals, they are referred to as fodder legumes and are frequently sown with grass fodder crops in mixtures. Legumes, due to the activity of the Rhizobium bacteria in the nodules formed on their roots, are often higher in nutritional value than grasses, particularly in the dry season. They have a higher content of protein, calcium and phosphorus and sometimes have a lower content than grasses of total fibre, or crude fibre as it is generally termed.
Although a great deal of experimental work has been done to determine the most suitable combination of grass and leguminous fodder crops, the ideal combinations for various areas have still to be discovered. The main problem is to find a grass and legume which can grow well together, without either one becoming dominant, and to identify the best times for sowing and cutting, also the most suitable spacing to adopt. In addition, fodder grasses are much easier to manage than grass-legume mixtures and a well managed crop of grass alone, with fertiliser application, may give a higher yield of dry matter and crude protein than a grass-legume mixture which has not been fertilised. The main factor to be considered, is therefore, the cost of purchasing and applying the fertiliser. Elephant grass, Guinea grass, Cenchrus ciliaris and Guatemala grass have all been used in mixtures with legumes such as Centrosema and Stylosanthes, with varying degrees of success.