agricultural production guidelines
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Veld in KwaZulu-Natal
Co-ordinated Extension KwaZulu-Natal Veld 3.4 1999
PLANNING FLEXIBLE AND OPEN VELD MANAGEMENT SYSTEMS
K G T Camp
KwaZulu-Natal Department of Agriculture
A Flexible Veld
Management System
An Open Veld Mangement System
A FLEXIBLE VELD MANAGEMENT SYSTEM
Two major shortcomings of most multi-camp grazing systems are that i) the period of stay in a camp tends to be too long and ii) the period of absence from a camp is too short. Both shortcomings can result in poor animal performance. In the flexible veld management system, both these principles of management (and the period of absence in particular) are manipulated according to the growth patterns of grass. These growth patterns vary through the season with fluctuations in climate (temperature and moisture) and stocking intensity. Animal performance is enhanced by ensuring that the animals have access to the highest quantity of the best quality forage available to them in the system. The flexible system requires a high level of expertise and the manager must be able to ‘read’ his veld effectively. The system was conceived and developed in KwaZulu-Natal, originally for use in sourveld, and has become known as the Venter-Drewes or Block system. (See also Production Guideline 9.8 of this series for addition information on flexible veld management systems.)
The main elements of the Venter-Drewes system are outlined below.
- Four blocks of more-or-less equivalent grazing capacity should be allocated to each group of animals. Each block may comprise one or more camps.
- One quarter of the veld (i.e. on block) is rested annually.
- The block which was rested in the previous season is burnt and camps in this block become the priority grazing camps for the group of animals, the stock being re-introduced whenever sufficient re-growth has occurred in these camps.
- Camps in the remaining blocks are utilized according to seasonal weather conditions, with camps in block two (the block which was the priority block in the previous grazing season) being grazed as second priority. During a wet season, fewer camps will be grazed in block two, and during a dry season more camps will grazed. The rest camps may be grazed only if severe drought conditions occur and there is no other grazing available. Herbage which accumulates during the rest year should be grazed when the veld is dormant during winter. In this case the animals should be provided with a good ‘winter’ lick as the herbage will be of low quality.
- To ensure that the herbage is kept short in the priority camps it is important that the group of animals allocated to the area is large enough to do so. Some farmers graze as many as 300 AU in one group to achieve this aim.
The following grazing manage schedule is recommended for each block in the system.
Year 1 Following a spring burn to remove residual, low-quality herbage which would have accumulated due to the full growing season's rest in the previous season, grazing must be closely controlled and selective grazing minimised. This is achieved by considering the camps in this recently burnt block as first in priority for grazing and returning the animals to those camps whenever sufficient regrowth has occurred since the last period of stay in those camps. Sufficient regrowth implies that the herbage has grown to a height which will allow the animals to get maximum intake with each bite. However, the herbage must not be allowed to grow out so much that it matures and loses quality. At the end of the grazing season this process of high utilization grazing (HUG) of quality material should ensure that the grazing animals perform well and that the veld will not require burning.
Year 2 At the start of the second year after the rest year the veld should be short, due to the HUG grazing management of the previous season, and a degree of high utilization grazing can be applied. Camps in this block become second in priority for grazing, being grazed after the priority grazing camps. A certain
amount of tuftiness is likely to appear in these camps, but burning should not be necessary at the end of the season.
Year 3 In the third year of the management cycle, camps in the block are managed according to the principle of controlled selective grazing (CGS). This set of camps can be regarded as reserve camps and utilization will depend on climatic conditions and how soon the animals return to the priority grazing camps. During wet seasons, and the peak growing period in particular, these camps will be lightly utilized, whereas in dry seasons regrowth in the priority grazing camps will be slow and these reserve camps will have a higher grazing intensity and become more fully utilized. In general however, animals will graze selectively in these camps and the veld will become tufty.
Year 4 Camps in the block are withdrawn from grazing for a full grazing season. The palatable grass species will receive an opportunity to re-establish their vigour and prepare for the following season's intensive grazing pressure. Herbage produced during the growing season may be used for providing animals with roughage in winter.
This flexible management system can be used as a closed system as described above, with a set number of camps being divided into four blocks and allocated to a group of livestock, or as an open management system with camps placed in different management groups, rotated each year, and being available to any stock group of livestock.
AN OPEN VELD MANAGEMENT SYSTEM
In this system a group of animals is not allocated to a fixed number of camps or camping system, instead the animals can be moved to any camp, and removed from a camp, according to whether the camp is ‘ready’ for grazing. The same principles of management that apply to the closed system need to be taken into consideration here. To do so requires both more hands-on management and a thorough knowledge of the veld. The farmer must be able to ‘read’ both the condition of the veld and current grazing patterns and react according to the needs of the veld and the animal. In addition, there is a greater need to keep accurate records of the utilization of the camps.
Annual decisions to be made
Which of the camps must be burnt?
This decision should be made in July following an inspection of all the camps on the farm. Should camps still have sufficient fodder which is required to carry animals through to the next growing season, the decision will have to be delayed. Additional usage of fodder might obviate the necessity for burning. It is essential, however, that no burning takes place once new growth has commenced.
No more that 25% of veld on the farm should be burnt in any year. A delay in spring rains places extreme pressure on the veld, animals and farmer, when excessive burning occurs.
Which of the camps must be rested?
Because of the short grazing cycle, camps in sourveld areas should be rested every fourth year. Mixed veld might require resting every fourth year, depending on the vigour of the palatable species. The recommended grazing cycle for sweetveld is 84 days. The two month rest period between periods of occupation may be sufficient time to constitute a vigour rest, provided that good growing conditions prevail (e.g. when good rains occur during such rest periods).
Most important is that veld condition, and in particular the vigour of the palatable species, should be used as an indicator for the need for rest. Veld low in vigour will produce poorly and a season's rest can increase production by as much as 30% or more.
A season's rest to produce a fodder bank for winter grazing can be regarded as a satisfactory rest provided it is not grazed until after the first frost, when growth should have ceased.
Decisions on camp utilization
The primary function of a veld management system is to maintain the veld in a sound, productive condition which will ensure good animal performance. To do this it is essential to ensure that supply (veld production) is not exceeded by demand (consumption of the animals) in any particular camp. This means that the duration a group of animals remains in a camp (period of stay) must depend on the size of the group, the size of the camp and the productive capacity (grazing capacity) of the camp. It is also essential that the camp has a sufficiently long period of rest (period of absence) to accumulate sufficient regrowth for the next period of stay.To achieve these planning objectives the steps outlined in Production Guidelines 3.2 and 3.3 must be followed. These are summarised as:
Step 1 Establish the productive capacity of each camp, that is, the grazing capacity in ha per AU.
Step 2 Calculate the grazing days per hectare per season for each camp.
Step 3 Calculate the number of grazing cycles per season or year.
Step 4 Calculate the number of AU’s that can be stocked in each camp. This is established from the size of the camp and the grazing capacity the camp.
Step 5 Calculate the grazing days (GD) per hectare per cycle per camp. While Step 2 will give a measure of the seasonal grazing that can be extracted from the camp, or grazing days per hectare per season, this step will give an indication of the acceptable GD/ha that can be utilized during each period of stay in the camp.
Step 6 Determine the size of stock groups in terms of Animal Units (AU’s).
Step 7 Determine the period of stay of the animals in the camp. This depends on the production and the size of the camp and the size of the stock
group in the camp. The situation can change during a season if the stock group's AU’s change, or from year to year if the grazing capacity changes. It is of vital importance to establish this accurately. Should this period be repeatedly too long, the animals will run short of quality food, animal production will be adversely affected and the veld will deteriorate.
Step 8 Calculate the period of absence from each camp. This should be regarded as a continuous period during which the camp is not grazed and is able to regrow and accumulate fodder for the next period of stay.
Period of Absence = Grazing cycle (days) - Period of stay (days).
These principles must be regarded as norms for effective management. Astute observations and accurate recording can refine each norm. For example, by observing the amount of palatable fodder remaining after each period of stay and at the end of the grazing season, and recording the season's animal performance and rainfall, adjustments can be made to the norms. In particular, the accuracy of the grazing capacity can be improved after several seasons' recordings.