Every livestock farmer is first and foremost a pasture farmer. He or she may make use of the natural grasses or he/she may improve his pastures by planting special grasses. A good farmer recognises the different grasses and understands how to get the best out of them. He will be able to distinguish between desirable and undesirable plants and he will know the grazing habits of his stock.
Understanding and managing pasture is highly complex, because there are so many parts to it, and each of these parts constantly change. For example, there are many varieties of plants used for grazing in any one area. Each plant has its own rhythm and will react differently to environmental conditions and treatment.
Different stock graze in a variety of ways. Sheep graze close but cannot handle long grass; goats browse on bushes while cattle eat long grass and are not as fussy as sheep.
Natural pasture is also constantly changing and developing according to the environment and number and types of animals that graze it. The changes can be good or bad. They are not always noticeable as they can take place very slowly. There is no doubt that man and animals have the ability to make rapid and bad changes to our native pastures.
A further problem is that farmers rarely have one sort of pasture. Most farms will have some natural pasture and some improved pastures. The natural pasture is often a mix of grasses with some grasses suiting one type of animal and others that suit a different type of stock. The improved pastures on a farm are specially planted to provide grazing at various times of the year and so need quite different management.
By understanding all the different parts that affect grassland, a farmer can begin to effectively manage his most important resource - his grazing.
Choosing a Pasture
Pastures are all different. They differ in terms of both the mix of plants which they are composed of, and in the way those plants grow (i.e. general plant health and vigour). For effective grazing, the pasture needs to match its use: the number and type of animals being grazed should be appropriate.
A new development available to farmers is coated seed. Grass seeds face many hazards before and during germination. They are light and can be blown away. They need precise amounts of moisture and nutrients to germinate and grow. If the seed is a legume, it requires a specific type of Rhizobium bacteria to enable it to fix nitrogen.
(Note: Fixing nitrogen is a term used to describe a process by which bacteria living on the roots of these legumes, extract nitrogen from the air and convert it into a form which is able to be used by plants).
A coating around the seed affords a great deal of protection at no extra cost. The coat protects the seed from stresses like acid or infertile soil, sun, wind and low moisture. Rodents and birds avoid coated seed. The coat can include a pesticide if necessary.
Coated seed flows easily making sowing by machine smoother. Even the light, woolly seeds like "Digit Grass" are more evenly distributed when coated. The coating makes all the seeds the same weight and size for precision drilling.
GROWTH AND DEVELOPMENT OF GRASSES
The growth and development of the grass plant can be divided into three phases:
The seedling is very small during this phase. It is using the maximum amount of light in order to produce carbohydrates. The small plantlet forms carbohydrates by photosynthesis. The carbohydrates are required for growth and development (particularly of the root system). Root development is extremely important to ensure the grass plant will receive the maximum amount of moisture and nutrients from the soil.
During Phase 1, the seedling is particularly sensitive to bad management by overgrazing. The tiny plant can be completely wiped out by the action of hooves and teeth. This phase begins at the early part of the growing season (the beginning of summer). It is important, if not essential, that paddocks have a substantial rest at this time to allow the successful establishment of these small grasses.
This is the vegetative stage when a vast amount of leafy material is produced. This is the phase of maximum production so should be the stage of maximum utilisation of the grazing.
The most important rule of native or natural pasture management is this: GRAZE HALF AND LEAVE HALF!
If this rule is applied whenever animals graze a particular paddock progress will be made in maintaining and regaining the vigour of the piece of grass. Many farmers misguidedly believe that this forces the stock to level the paddock and so remove the long tufty grass that is not productive. This thinking is misguided.
Firstly, stock that are fussy will not touch the long, tufty grass preferring instead to graze to the last any sweeter more palatable vegetation (which will include the vulnerable new shoots). This puts an enormous strain on the more desirable grass which, in time, will become exhausted and die out.
Secondly, it is vitally important to leave a certain amount of leaf canopy remains after each period of grazing. This enables plants to recover quickly from that grazing. The leaf is essential for the plant to form more carbohydrates to replace those that were grazed off.
If a farmer wants to level the grazing he should do this mechanically with mower rather than have it grazed down severely. The "graze half,leave half" rule applies as much to cutting. If a plant is severely cut or grazed, the roots will stop growing within twenty four hours. If 50% of the leaves are removed, the roots will continue to grow but at a slower rate. Removal of more than 50% of the leaves may stop root growth for three to eight days. The roots start dying back from their tips above 80% defoliation.
This is the reproductive phase which is essential for the development and release of the seed. Seeds are necessary for the establishment and maintenance of pasture. The farmer will want to encourage the reproduction of the more desirable grass species. The farmer will also want to ensure good cover and good herbage production which will allow him/her to stock the land well.
These three phases coincide with the summer period from early November through to March or April as shown in table 1.
Table 1: The times of the phases of grass growth and development.
1 November and December
2 January and early February
3 Late February and early March
It is important to be aware of the times of the phases so that essential rest periods can be built into the grazing management program. This will ensure that there is no mismanagement of the grass.
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