By DENNIS MCDONALD
As I’ve written previously, all the problems in the world seem to have started when Eve misled Adam. Quite early on after his ‘fall’, and ever since, Adam has been accused of overstocking the earth with his domesticated animals. Prominent among the denialists have been the grazing gurus John Acocks and Allan Savory. Both have pointed out that ‘overgrazing’ can be caused by one animal if it is allowed to re-graze certain plants before they have had time to recover.
Both have explained how plants were allowed to rest prior to Adam messing things up. Acocks explained it as follows: ‘Wild animals were free to roam, and they had a habit of congregating in large herds and “trekking”, so the veld was grazed heavily but intermittently, and not continuously.’
John Acocks (7 April 1911 – 20 May 1979) was a South African botanist and pasture ecologist, and author of ‘Veld Types of South Africa’. For most of his working life, he was posted at the Grootfontein College of Agriculture in Middelburg. His pioneering views on veld rehabilitation and management relevant for South African farmers today. Read more about him here.
Savory, I would guess, would largely agree. But, as evidenced by the wildebeest migration in the Serengeti, not all animals migrate. That is, significant herding animals such as the buffalo do not join in, and besides that, not all game animals are herding animals.
Allan Savory is a world-renowned rangeland consultant and expert in regenerative agriculture. Born in Zimbabwe, where he spent most of his earlier life as farmer, soldier, game manager and politician, he is the president and co-founder of the Savory Institute, which supports the restoration of grasslands across the globe. Read more about him here.
Here Savory offered an interesting alternative explanation. Considering how plants rested in their ‘natural state’, he suggested that the large herds so fouled the grazed areas with urine and dung that other animals were put off grazing there for some time.
The question then is why Acocks and Savory proposed that modern man – with the aid of fencing — should prevent animals from re-grazing plants before they’ve had time to recover. Bear in mind that, to herbivores, succulent regrowth is like candy to a child. Well, like many others, including staff at the South African agricultural colleges at the time, they proposed creating a number of fenced camps for each herd of animals run on a property. Savory referred to such a grouping of paddocks as a grazing cell.
However, quite early on, Acocks came into conflict with the Department of Agriculture (‘the Department’) in that he advocated considerably more paddocks per cell. The problem was aggravated by the fact that he was essentially in Department’s employ, as he worked at the Grootfontein Agricultural College.
There is a relatively simple explanation for some of the vitriol behind this conflict. At the time, the Department wanted to roll out a ‘grazing system’ to as many farmers as possible. Officials thought they could entice farmers into the scheme by offering subsidies for fencing and watering systems, but were reluctant to subsidise too many camps. And here, in their employ, they had the ‘fanatic’ Acocks, insisting that more camps per herd were needed. To be specific, the ‘Department’ thought three or four camps per herd were sufficient, whereas Acocks started off by advocating 12 camps per herd, and then upped it to 16.
The number of camps advocated was probably not the main bone of contention. Acocks’s cardinal sin was hisclaim that, under his system, stock numbers could be doubled. Many people think overgrazing and overstocking are the same thing.
According to the M. Timm Hoffman, Professor of Plant Conservation at the University of Cape Town, ‘He felt that by forcing animals to graze all species non-selectively, the more palatable elements would be able to out-compete the less palatable species and dominate the vegetation as he believed they once did in pre-colonial times’.
In terms of history, Acocks is the elder statesman. Savory visited Acocks to glean ideas. He then came up with what he called Short Duration Grazing, as opposed to Acocks’s Non-Selective Grazing. So, for a while the acronyms NSG and SDG occupied centre stage. What is interesting is that both advocated 16 camps per herd. The difference was that while Acocks advocated rest periods of five to six months, Savory was advising one to three months.
Savory advocated varying the rest period according to the growth rate — that is, a short rest when growth was rapid. The reason for the relatively large number of camps was that this would eliminate the repeat grazing of plants during the extended graze period that is inevitable with a small number of camps.
There was little difference between the rest period advocated by ‘the Department’ and by Acocks. If for example both agreed on about 150 days, one can make some calculations. To calculate the graze period, one has to divide the rest period by the number of camps minus 1. (One camp is being grazed — that is, from the beginning of the graze period to the end of the graze period it is not resting.) So, in a four-camp system with a 150-day rest period, the graze period for each camp is 150 divided by 3, namely 50 days. (Note that this graze period is almost as long as Savory’s longer rest period.) The same calculation for a 16-camp system is 150 days divided by 15, namely 10 days.
For interest’s sake, if one uses a 60-day rest period with a 16-camp system, the graze period would be four days. Importantly, Acocks regarded the 50-day graze period as far too long, as the re-grazing of plants would be inevitable.
So Acocks and Savory agreed on the number of camps, but differed on the length of the rest periods. Acocks and the Department agreed when it came to the length of the rest period, but differed on the number of camps required. In a strange way, Savory also agreed with some officials in ‘the Department’.
At more or less this time, Prof J.O. Grunow and others developed what they called Controlled Selective Grazing, or CSG. They also advocated a short rest (and consequently short graze) system. They reasoned that, if allowed to graze more selectively, animals would select the better or more palatable species, and the poorer grasses would then die out from underutilization (as explained earlier in ‘The wonders of grass’). Grunow advocated eight to 12 camps, but a conservative stocking rate. By coincidence or cross-pollination, Savory described the process of poorer grasses dying out in much the same way.
Prof Grunow died at a relatively early age, and Savory seems to have abandoned this idea in later years. To my knowledge, CSG is no longer advocated by anybody. This I think is largely due to the fact that while sounding like a nice idea, things simply do not work in this manner. That is, the better plants are the ones that are capable of suffocating themselves, while the poorer plants are able to survive when left ungrazed. Added to this, during the winter months in sweetveld areas, the poorer grasses are often as palatable if not more palatable than the climax grasses.
Savory has continuously refined his ideas, and describing them in any detail is beyond the scope of this article. He no longer advocates a ‘grazing system’ but rather a grazing method, which involves constant adjustments based on feedback from monitoring.
One observation might be mentioned. In the early days, Savory advocated continuing with a relatively short rotations through the winter period. That is, camps could be grazed two or three times during the winter months even though no regrowth had taken place. The reasoning behind this was that a better plane of nutrition would be maintained for longer if animals took down the camps in stages.
In later years, he proposed a single winter rotation. That is, one rotation was planned from the time that summer growth stopped until the next good rains could be expected. This dry period in some parts can be more than six months. Since the difference between Non-Selective Grazing and the old Short Duration Grazing is essentially the rest period or cycle length, one could say that he now advocated SDG for the summer months and NSG for the winter months.
This strikes a chord with me as far as sweetveld is concerned. The better sweetveld grasses can become unpalatable when they grow vigorously in the summer months and are not grazed or trampled down in the winter months. If this more or less forced grazing or trampling does not occur in the dormant season, the better grasses can smother themselves with their own dead material. However, in the sourveld areas, Non-Selective Grazing might be more appropriate.
Neil Tainton suggests just this in his edited book Veld Management in South Africa. It would of course be convenient for this model if Acocks had operated exclusively in sourveld areas, and Savory exclusively in sweetveld. The truth is that they both operated in both these veld types.
In the grazing literature, much is written about various grass species ‘outcompeting’ one another. Less is said about exactly how this happens. Any gardener will tell you how difficult it is to grow a lawn in the shade of a tree. Perhaps some grass species outcompete others if we create the conditions for them to do so. Perhaps the ‘competition’ is for sunlight. Perhaps these conditions are created in the sourveld areas when we allow animals to graze selectively. That is, if palatable grass plants are grazed short and the adjacent, less palatable grass plants are left ungrazed, the unpalatable plants could well shade the other to death. This will of course be compounded if the palatable grasses are repeatedly grazed during a protracted graze period.
The suggested process is specific to sourveld. The poorer grasses in sourveld regions are more robust than their equivalents in the sweetveld regions, and are also less palatable than their sweetveld equivalents. One could say that what makes a grass a ‘poor’ grass in the sweetveld areas is the fact that it produces little. And what makes a grass ‘poor’ in the sourveld regions is the fact that it is unpalatable.
While climax grasses can shade themselves to death in sweetveld, the poorer grasses seem to shade the climax grasses to death in the sourveld areas. This is simply a hypothesis, and needs to be examined by people more familiar with sourveld regions. Isolating the competition for sunlight as the mechanism leading to change in the veld composition may be a crass oversimplification. There are other areas of competition such as competition for water, but perhaps competition for sunlight is the overriding factor.
The following photographs taken in the Tussen Die Riviere Game Reserve in the southern Free State (between the Caledon and Orange Rivers) may illustrate the point.
Photo 1: In the foreground are heavily grazed Red grass or Themeda plants. In the background are Turpentine or Cymbopogon plants, which are very unpalatable. They have been grazed, albeit with a long tooth. This is due to the animals’ preference for the area. Once a pattern has been established, it is repeated. If the grazing pressure was not so severe, the less palatable Turpentine grass would probably be untouched, and it would be easy to imagine it shading or overwhelming the severely grazed Red grass.
As the Australian expert Dr Chistine Jones puts it in a report on the path-breaking Rangelands Project, ‘Allowing stock to remain on pastures during early regrowth stages will severely deplete plant energy reserves, resulting in the formation of a steady-state type of equilibrium, where both tops and roots remain restricted in size, such as is found in mown turf and continuously grazed grassland.’ The Red grass in this photo seems to be in this ‘steady-state type of equilibrium’.
By way of contrast, Jones continues: ‘If desirable grasses are rested from continuous grazing and then defoliated in a single grazing event (such as in cell, planned, or pulsed grazing), a large proportion of roots cease respiring and die within a few hours of the removal of the leaves, in order to equalise the biomass. The root pruning effect is regenerative rather than degenerative. These “pruned roots” provide extremely valuable organic matter which improves the physical, chemical and biological attributes of the soil.’
Photo 2: Overgrazing and area selection resulting in erosion. This is repeated defoliation without time to recover.
Photo 3: Overgrazing resulting in weeds as pioneer plants. This is repetitive defoliation and not overstocking. Look at this in conjunction with photos 4 and 5.
Photo 4: Photos 2 and 3 were taken very close to each other. This photo shows rank Turpentine grass, and it is easy to see how it could ‘out-compete’ other species. Tussen Die Riviere is probably in a transitional zone between sweet and sour veld. All these photos were taken in the same area where the herding animals tend to congregate.
Photo 5: Undergrazing resulting in moribund plants. Photo taken on the same day in the same reserve as the previous photos, but some distance way from all the others This seems to reflectg Acocks’s axiom that South African rangeland is ‘understocked and overgrazed.’
All about burning
Palatability is a major issue in sourveld. Even the more palatable species become unpalatable if allowed to grow too rank. Here fire is the great leveller. But again, there is controversy among different camps as to what is natural and un-natural. Even the most ardent pyromaniacs, and there are many, agree that it is bad to burn sweetveld. Given this, lightning strikes in sweetveld areas should probably be regarded as not ‘natural’ but rather as an ‘act of God’. But the debate goes further in that some would argue that fires started by early man are also somehow natural. There is yet further debate as to how frequently early man used fire compared to modern man. Essentially this debate is irrelevant. Fire, like a spade or plough, is a tool that can be used to good or ill effect. However, like surgery, it should be used to correct a malaise.
Dr Christine Jones, a rising star in the world of regenerative farming.
On the subject of fire, Christine Jones again says it best: ‘Regular burning is extremely detrimental to soft forms of native ground cover. It encourages a dominance of fire-tolerant, relatively unpalatable, warm-season perennial grasses such as blady grass (Imperata cylindrica), bunch spear grass (Heteropogon contortus), African love grass (Eragrostis curvula) and Coolatai grass (Hyparrhenia hirta). These are often the very species it is hoped that burning will reduce.
‘Hot burns remove surface litter, leaving the soil unprotected. The loss of organic matter in turn reduces the level of soil biological activity, nutrient cycling, nutrient availability, soil porosity, soil water-holding capacity and soil structure. Reduced rates of infiltration are reflected in increased rates of runoff, accompanied by the movement of sediment, surface organic matter and animal dung to waterways.
‘Although burning may produce palatable regrowth in the short term, it dramatically reduces the quality of ground cover over the longer term. The native species which are the most nutritious from an animal production perspective (including perennial native legumes and cool-season native grasses) are not tolerant of a combination of burning and grazing. The recruitment of productive native legumes and grasses is favoured by a mulched soil surface, which is destroyed by regular burning.
‘The use of fire for the removal of excess growth may appear attractive, but results in atmospheric pollution, the loss of many nutrients which would be recycled in the grazing process, loss of surface litter, and, if used frequently, bare ground. Landholders may have valid reasons to use fire, such as woody weed control, or the enhancement of fire dependent species. However, in view of the risks, fire is a tool which should be used cautiously and infrequently.’
FEATURED IMAGE: A camp on Hanglip Farm, east of Colesberg. (Riaan de Villiers)