Veld Management practices.
Prof Chris S Dannhauser
We have seen in the first three articles of this series that grass species differ in terms of palatability and how it can influence the grazing habit of animals. Animals will graze the palatable ones first, then the semi palatable ones and most of the unpalatable ones will not be grazed, unless you force the animals with high stocking rate. This natural grazing pattern is called the “Take half, leave half principle” and is presently used as a management system. In the next paragraph a more detail description will be given.
4.1 The take half leave half principle
The reality of the take half, leave half grazing system is that palatable grasses are selected before semi-palatable and unpalatable grasses, as shown in Figure 3.1. This figure shows an unpalatable grass tuft not grazed, a semi-palatable grass that was grazed half way and a palatable grass of which two thirds of the above ground material was grazed.
Figure 3.1: The end result of grazing according to the take half, leave half approach.
Photo 3.1 shows how a camp should look like if the take half, leave half grazing approach was applied.
Photo 3.1: Half was grazed and half not.
If the veld is managed as shown in Figure 3.1 and Photo 3.1 the veld quality and grazing potential, as well as animal production can improve.
The important fact is that over stocking and over grazing can damage veld seriously. On the other hand underutilization can also cause damage to veld.
4.2 What are the effects of overgrazing on the grass plant?
Any plant should have sufficient green leaves to photosynthesize and that is the process in which energy is produced for the plant for good production. Every living organism like grass, animals and human beings needs energy to stay alive and to grow.
The energy produced, by the plant self, is used for leaf, stem and root growth. The leaves are the energy factories of the plant. When plants are grazed moderately, excess energy can be produced, which is then stored in the roots during autumn for winter survival. This stored energy is essential for the grass plant, when re-growth starts in the beginning of the next summer.
If the veld is overstocked during summer and the animals graze the young developing leafs (the energy factories) frequently no energy can be produced. Under these circumstances the energy reserves, that was stored in the roots during the previous autumn, will be utilized for regrowth in the new season. If the grazing continues the roots will start dying and eventually the whole grass tuft will die, due to a lack of energy and nutrients.
The photo on the right hand side of Figure 3.2 shows what happens to the roots of a grass tuft that was grazed too short. Compare that with the roots of a plant that was not grazed too short on the left hand side of Figure 3.2
Figure 3.2: An indication of the reduction of grass plant roots after severe defoliation/overgrazing.
Total under-grazing can be just as harmful as overgrazing. If leaves are not removed, they become old and they will overshadow young leaf growth. If there is no direct sun the energy production slows down and leafs (or the whole plant) might die, as shown in Photo 3.2. The plants become moribund (slow death) and will die eventually.
This process can also be positive in the take half, leave half grazing system. Remember the unpalatable grasses are not grazed in this system, so they will die eventually and give space to more palatable grasses to grow.
The consequences of over-grazing or over-utilization, which was explained previously, emphasized the need of regular short duration periods of rest to keep the grass tufts vigorous. It is also to the benefit of the animal, because they can graze young, nutritious plant material in the form of regrowth after a short rest. This is only possible if the stocking rate is realistic and the palatable grasses are not grazed too frequent and too severe.
Research, over many years, indicated that short duration rest alone is not enough. Veld also needs long duration rest, which means a full growing season rest. The growing season in the summer rainfall areas is normally 4 to 6 months long, starting in October or November (see Figure 3.3). A full growing season rest is when the veld is resting during the rainy season, when the grasses grow actively. The grazing material (grass leaves) that was produced in the growing period can then be grazed in the autumn, winter and spring (March to September).
Figure 3.3: The cattle farmer’s CALENDER:
There are two important reasons why this long duration rest should be applied:
- It allows the grass to produce seed and
- The energy that is produced during the growing season (photosynthesis) can be stored in the roots during autumn to form reserves, which is important for growth in the following summer season (as indicated earlier).
Research showed that a full season rest for two out of every three years is adequate and important. To apply that on the veld, the farm should be divided in three different units, as shown in Figure 3.4. That goes in in hand with the three seasons shown in cattle farmer’s calendar (Figure 3.3) Figure 3.5 shows how the rotational grazing can be applies on the three units of the farm during the three seasons.
One third could rest every year if the grazing sequence is followed, as shown in Figure 3.5, and two years of rest in a three year period is possible.
Figure 3.5: How to incorporating rest in your veld management system
In the first year, Unit 1 is grazed from November to February and Units 2 and 3 are rested during the same period. During Year 2 and 3 the rotation of animals, as indicated in Figure 3.5, should be followed. It is very important to take notice of the sequence of grazing and resting in the figure. Unit 1 rests in Year 2 and 3, Unit 2 rests in Year 1 and 3 and Unit 3 rests in Year 1 and 2. In Year 4 you start with the same program that was followed in Year1.
To apply an economic veld grazing system (sheep, cattle or dairy) you should know the grass species, the composition of your veld. It is also important to know what the grazing potential of your veld is, to carry the correct number of animals, so that you do not overstock the veld and not allow overgrazing and to apply also efficient rest.
Prof Chris S Dannhauser
Sel no (+27) 082 873 4736