The application of certain fundamental principles is more important than the actual system of management; a system is merely the methodical application of principles within the limitations imposed by the number of paddocks available for each herd.
Climatically, Southern Africa varies very widely, from moist high altitude mountain vegetation to arid low lying semi-desert, therefore the principles as applied to veld management will vary in their importance of application. However, basic principles have been established and should not be confused with contributing factors such as availability of stock water supplies, bush control and managerial ability to name just a few. It is assumed that these factors are under control and will not be discussed further.
The main principle of veld management following defoliation of grass is rest of sufficient duration to allow grasses to replenish growth reserves and, where necessary, to restore seed supplies where these have been depleted.
The effect of grazing is to remove the leafy part of the grass plant, i.e. the parts that manufacture plant foods. Frequent and close grazing reduces the ability of the grass plant to produce plant foods, and new growth on a completely defoliated grass plant develops at the expense of the stored root reserves. Rest, after periods of grazing, enables the grass plant to replenish growth reserves, and vigour is thus maintained.
PERIOD OF UTILIZATION
Animals tend to go back to those plants already grazed. If the period of utilization is too long, there is the possibility that selected plants will be overgrazed – usually the more palatable species. Conversely, if the period of utilization is too short, grass production will be lost – unless there are sufficient numbers of stock or adequate paddocks, and under-grazing of grasses would result. This would lead to an over-accumulation of old plant material and consequent loss of vigour.
When split-season systems are used, the period of utilization should be six to eight weeks whilst with multi-paddock or intensive systems, the period of utilization should not exceed three weeks.
NUMBERS OF STOCK
It is not so much the actual numbers of grazing stock that matter, as ‘ their sum effect on individual components of the vegetation – this could possibly be termed the weakest link in the “veld chain. The weakest link could be palatable browse in bush land, or specific palatable grasses in grassland. If the effect of feeding animals is to eliminate these palatable species, then either too many animals are being grazed, or the system is at fault. Therefore, the number of stock bears a direct relationship to veld condition Naturally rest period of utilization and numbers of stock, are interrelated, and together will determine the frequency of utilization.
EQUAL UTILIZATION OR THE REMOVAL OF TOP HAMPER
If old dead material is allowed to accumulate on a tuft of grass, its effect is to shade out new shoots that develop from the basal-buds within the tuft and the tuft will become moribund and die. The removal of dead grass material is therefore important, but its importance is variable. It is essential in perennial grassland, but not in annual grassland, since annuals cannot become moribund as they live for only one season, and rely on seed for self-propagation.
If equal utilization of all grass plants can be achieved, the removal of top-hamper is automatic; unfortunately, this is seldom the case and some effort must be made to assist the grass by knocking down or removing this dead material. The fencing in of similar grass areas wherever practicable does, however, help to achieve equal utilization. In this way, grazing can be managed according to its particular requirements; for example, the use of vleis in spring.
Where equal utilization cannot be achieved, old material can be removed by concentrating animals artificially, such as moving licks around moribund areas. Fire can also be used as a last resort – provided there is adequate soil cover, and burns are not too frequent.
The detrimental effect of top-hamper can be put to good use in that undesirable grasses can be purposely under grazed, thereby assisting them to become moribund and die. Then, through good management, more desirable or palatable species are encouraged.
- APPLICATION OF VELD MANAGEMENT SYSTEMS
As discussed, the main principle of veld management following defoliation of grass is rest of sufficient duration to allow replenishment of growth reserves. Therefore, the more paddocks provided per herd, the easier it is to implement a system of veld management with adequate rest periods, and the easier it is to follow refined systems of animal management. It is thus in the interests of both the veld and the animal to provide as many paddocks per herd as is possible within the economic limits of the farming unit. In addition, the more paddocks per herd, the less sensitive the system is to mismanagement. In this light, the implementation of any veld management system becomes a progressive series of paddock sub-division until a stage of economic limitation is reached which will ensure stability of the veld and maximum animal production.
CONTINUOUS LIGHT STOCKING
The chances of applying a veld management system, other than by herding, on a farm that is only ring-fenced, are extremely difficult, and stocking rates must be adjusted to limit selective over-grazing. This necessitates .light stocking well within the carrying capacity of the veld. However, even this very basic consideration whereby correct stocking-rates are applied can lead to an improvement in herbage production, species composition and basal cover.
From an obviously undesirable situation where some provision for rest is only ensured by light stocking, the second logical stage in the development of a veld management system is the introduction of two paddocks per herd, or a “split-season” system, where the growing season is split into early and late growing seasons, the veld being grazed and rested as indicated in Figure 1.
Figure 1. “Split season” grazing system. One herd: two paddocks
|Paddock 1||Paddock 2|
|YEAR 1||Late Summer||Graze||Rest|
|YEAR 2||Late Summer||Rest||Graze|
The aim in this system is to provide a late season rest to build up growth reserves, followed by an early season rest to allow the grass to exploit its increase growth reserves, hereby ensuring increased vigour.
A further refinement to this system is the provision of a third paddock to ease the grazing pressure in the early summer (Figure 2)
Figure 2. “Split season” grazing system. One herd: three paddocks
|Paddock 1||Paddock 2||Paddock 3|
|YEAR 1||Late Summer||Rest||Graze||Rest|
|YEAR 2||Late Summer||Rest||Rest||Graze|
|YEAR 3||Late Summer||Graze||Rest||Rest|
Split season systems have not been applied to any great extent, but where this type of management has been applied the results have been encouraging. The veld has improved and maintained excellent condition, with a vigorous grass cover and abundant evidence of a healthy soil cover.
It must be mentioned that split -season systems have some very definite disadvantages, the worst being the concentration of stock in the early summer period when the availability of grazing could be limited through a late start to the rains. This could be catered for by spreading the herd over the entire farm until such time as grass is available in sufficient quantity to concentrate the herd and operate the system. It is also extremely important that the herd is not kept in the early summer paddock too long – this could result in excessive overgrazing from which the plants may not recover. The timing of the change is therefore vital to the success of this type of system and if in doubt it is preferable to move too soon rather than too late.
ONE HERD, FOUR PADDOCK SYSTEMS
The next step in this sequence of veld management systems is the development of the one-herd four paddock system. Here one herd is run in an arrangement of four paddocks, one of which is used for the growing season in any one grazing year while two provide for the dry season – autumn and winter – and one is rested for burning. During the early growing season when grass could be in short supply, the herd is divided between or rotated through three paddocks and then confined to the growing season paddock as soon as the condition of the grazing permits.
This system is really a slight variation of the split-season system with the introduction of fire to control encroaching bush. Fire has its uses in veld management and can be an extremely useful tool, especially where moribund grass cannot be removed by other means. In this instance, fire will release the nutrients held by the moribund grass and return them to the soil in the form of ash; fire will thereby replenish the nutrient cycle in the soil and, at the same time, remove the top hamper.
However, because fire is extremely destructive of soil cover, it should be used as infrequently as possible.
Where four paddocks are available per herd, this could be used as a step towards intensive systems where each paddock is grazed for two weeks and rested for six weeks.
The final stage in the intensification of veld management is the development of the High Intensity Short Duration or Intensive Systems. The plural is used because in this method of management there is no one system and no set number of paddocks; a minimum of five, preferably six, paddocks, is provided per herd. The basic rules of these systems require as short a grazing period as possible, a suggested maximum being two to three weeks – and a long rest period – the suggested minimum being six to eight weeks. These suggested maxima and minima should, theoretically, vary with the time of year, condition of the veld, and the stocking rate. At present they are only suggestions; more experience in the application of intensive systems will undoubtedly bring about changes, especially in different environments. As the systems stand at present, extremely encouraging results are being achieved. Grass vigour and herbage yields have improved rapidly, with attendant improvement in soil condition, water infiltration, and a consequent reduction of soil erosion.
A simple illustration of an intensive system of six paddocks per herd is given in Figure 3. This shows a system having a two-week grazing period, reduced to a one-week grazing period in early summer when grass could be slow in growth.
Some criticism is still levelled at this system. It is largely centred around the aspect of animal management, for example, the running of single sire herds, and the tendency for calves to be mislaid at each change of paddock. These are management problems which can be overcome by dispersing the herd into single sire units and operating a split season system for the breeding season, or by moving cows and calves to adjacent paddocks. There is also no provision for bush control; this, however can be built into any system.
As is the case with other systems of veld management, there are certain aspects of any intensive system that require close attention. The critical period of slow grass growth in early summer applies equally to intensive systems – if anything, it is even more important to assess the amount of grass available. Grazing periods should be reduced if necessary or it may be a case for opening two paddocks per grazing period. Nutrition plays a critical part in reconception in the breeding animal, and this class of animal is thus very susceptible to shortage of herbage at this time of the year. However, availability of herbage is important throughout the year and at no time should animals be kept in a paddock for the two week period if grass is in short supply – not only will animal performance be jeopardized but intensive utilization can also be damaging to the grass plant.
To be successful, records of animal numbers and grazing periods should be kept, from which the number of cattle grazing per hectare per day (cattle days per hectare or c.d.h.) can be calculated. With this valuable information, grazing periods, intensity of utilization and herd movements can be planned with particular reference to the sensitive summer periods. In our better rainfall areas an early summer utilization of 16 cattle days per ha is often all that can be planned with a maximum of 24 cattle days per ha. Late in summer this figure builds up to 36 cattle days per ha, while during the summer period, 48 cattle days per ha should not be exceeded per grazing period. In winter and in particular, late winter, this figure can be exceeded; in fact, heavier stock pressures at this time tend to assist in knocking down old unused grass material.
Records will also indicate if a particular paddock is being grazed at the same time each year-where this is the case, grazing periods can be varied or an additional, paddock could be planned for the rotation.
Intensive systems are sensitive to stocking rate in that stocking rate will dictate intensity of utilization. Where this is excessive, grass plants can be damaged, even if the period of utilization is followed by a long rest. Therefore, increases in animal numbers should be made with caution but only where increased grass production over more than one season indicates that more animals can be carried. Failure to observe this basic rule has resulted in a number of catastrophes.
Although managerial ability is also involved, it would appear that breeding herds should not exceed 150 cows; this point is of special significance during the bulling season.
Veld management is receiving unprecedented interest. However, interest alone is not enough. We must take positive steps to reclaim. Maintain or improve the veld and so ensure the production of grass and of stock at a sustained high level.
Split season and intensive systems provide the most efficient means of achieving this end.
* 1 acre = 0.4 hectare (approx)
* 1 hectare = 2.5 acres (approx)
Figure 3: A simple illustration of an intensive system of six paddocks per herd