Know your ranch’s grass

This week Abré J Steyn presents a simple and efficient way of monitoring the grazing value of veld, along with a user-friendly guide to the key grass species.

The correct use of fire is a valuable tool on a game farm in the prevention of bush encroachment by maintaining the balance between grass, shrubs and trees.

Photo: Abré J Steyn

 

Last week Abré J Steyn explained how important it is for game ranchers to realise that they are in essence grass farmers, and their success or failure in producing game is a result of how well they can farm with grass. This week he presents a simple and efficient way of monitoring the grazing value of veld, along with a user-friendly guide to the key grass species.

The health and reproductive capacity of all species depend ultimately on the quality of their nutrition. In few species is it more noticeable than the cases of the tsessebe, roan and sable antelope. The reason they are so scarce and valuable is linked to a limited rate of reproduction, induced by their highly selective feeding habits. They are specialist grazers that depend on a limited amount of highly nutritious grasses that have become scarce or absent on many game farms.

Even in the Kruger Park, the number of roan have dwindled through the years. At one stage they were all isolated in a huge enclosure as a protection against predators, but no amount of unfortunate predator culling could stop the decline of the roan, as their real enemy was impala, which proliferated in abundance without being controlled by the reduced number of predators. My estimate is that there is an overpopulation of 500 000 impala in the park, which decimates the grazing to such an extent that it has an adverse effect on the health and reproduction of the roan. The smaller any fenced-in area is, the more severe is the effect of how the veld is managed. In the Percy Fyfe Nature Reserve, where the herd of the last free-roaming roan in SA was established more than 40 years ago, little progress resulted, due solely to poor veld management.

Grazing science
Grazing management of fenced-in game areas is however still a very new ­science and depends on ­understanding the role of different grass species in the ­environment and how they react to different stimuli or management ­practices. Our level of understanding is by no means complete. What we do know is that certain grass species will decrease and eventually ­disappear under any form of ­mismanagement. Collectively they are known as the “decreasers”. They are usually the most palatable and nutritious species, which also grow in the most fertile soil.

The grass species that replace them are known as “increasers”, which are ­usually unpalatable and don’t attract ­grazing ­animals, whose absence will in time ­enable the area to recover. Although seen in the long term as a way in which the ­fertile areas are ­protected against ­erosion, the short-term ­implication for the game farmer is severe loss of ­productivity and income. Most of the grass species we understand well enough can be ­classified as either decreasers or increasers.

Definitions
Decreaser: a dominant grass in good, well-managed veld that will decrease under any form of mismanagement, such as severe disturbance, untimely burn, overgrazing or under-utilisation.
Increaser: a grass species that will increase under any type of ­mismanagement or disturbance.
There are two types of increasers:
Increaser I: a grass species that will increase under conditions of under­utilisation or understocking or on an area which is selectively undergrazed.
Increaser II: a grass species that is dominant in poor veld or that will increase under any form of overgrazing or disturbance.
There are three types of Increaser IIs:
Increaser IIa: A species that increases with mild overgrazing.
Increaser IIb: A species that increases with moderate overgrazing.
Increaser IIc: A species that increases with severe overgrazing.

DIY veld monitoring
With a knowledge of the different grass species acquired in the manner described last week, and by ­referring to the table (pages 50, 51), a game rancher is now equipped to carry out his own ­monitoring and grazing evaluation. As far as I am aware, this table is the first attempt to present this information in a concise and user-friendly form. It should be kept for future reference and used once the rancher knows his or her grasses. I must stress that there is nothing of greater ­importance to be done on a game farm than regular veld monitoring, and if the cost, time and effort devoted to that is compared to the cost put into development of infrastructure such as fencing, roads, water supply, accommodation, and so on, it is minuscule. The time to do it is in the growing season, when the grasses are in flower, which is also the off-season.

Once you are sufficiently familiar with the dominant grass species, you can proceed with the monitoring as follows: get a length of rope just over 50m long. Ordinary ski rope is fine as long as it does not stretch too much. Splice an eye or loop at one end and secure it so it will not become undone. The eye need not be large – only a peg or steel dropper needs to go through it.

Now make 50 overhand knots in the rope exactly 1m apart, starting the first knot 1m from the eye. Splice another eye 1m from the last knot and cut off. The rope should now be 51m long. Install the rope on a reel similar to those used for long electrical leads. This is now your monitoring tool. There are fancy and expensive wheel-point gadgets used by botanists available, but for me a rope works better.
The next thing is to establish your monitoring transects. For this you need some lengths of old steel household water pipe (or new, if you can still find it). With a grinder, cut it into lengths of at least 60cm so that one end is square, but with the other at an angle to penetrate the soil easier. For sandy soil they should be longer, even 1m. Select at random any point in your veld and drive one of the pipes into the ground. Pile some stones around it or mark it in some other way so that it does not present a ­hazard and you can find it again.

Put a peg or steel dropper into the pipe. Fit one eye of the rope over the peg and slide it down to the pipe. Stretch the rope in any direction and drive another pipe in the ground so when the rope is fitted over the peg on that side it will be tight. The pipes are now 51m apart and this becomes a permanent monitoring transect. The pipes will ensure that you use the same sampling points every time.
Walk along the rope from one end to the other. At each knot push a ­dropper or your walking-stick straight down and record the following:
1. Whether the stick touched the base of a grass plant. This is your basal grass cover.
2. Determine whether the plant that you touched (or if no plant was touched then the plant closest to your stick) is a grass, herb, shrub or a tree. This is your plant composition. But most important:
3. If it is a grass, identify it, and if it was not a grass, identify the grass ­closest to the stick and from the attached table determine whether it is a decreaser or increaser I, IIa, IIb or IIc. These values will indicate the grass composition and the quality of the grazing.

Now multiply all your values by two to get a percentage as you only used 50 sampling points, and your results may look something like this:
You don’t have to be able to identify all the grass species. It is rare that more than 10 species are dominant on a farm, and it is their frequency of occurrence and how this changes over time that are important. Until you get to know the lesser species, they can just be entered as “unknown”.

The results of steps 1 and 2 are not essential, but are figures for your own ­interest. The results of step 3 however are what you are after, and can be ­submitted to an expert, such as Professor Noel van Rooyen, who has done ­extensive research in this regard and compiled sophisticated computer ­programmes to determine carrying ­capacity for game.

If you supply him with your results of step 3 together with an estimation of the ­relationship of the crown cover of the grass versus trees/shrubs (how it will look when viewed from above), he can quite accurately determine the ­carrying capacity for the game species that are presently stocked or that you want to stock in future, and indicate how this will vary under ­different rainfall conditions, as he has access to all rainfall figures in South Africa.

These surveys must be done on all parts of your farm, especially in the different plant communities. You can establish as many fixed transects as you like, and they can cut across each other, but must ideally be done at the same time each year as you will be monitoring any trends that take place.

This is the best way to run a game farm scientifically. I urge you to ­introduce it as this way you will derive more ­pleasure and profit from your farm. Your soil will retain ­moisture much longer and will withstand the effects of droughts much better, you will avoid bush ­encroachment, your calving ­percentage – especially of rarer species – will rise, your game will be healthier, and the size of your trophy animals will improve.
All this because you really started to farm with grass.

The primary source for this series was Guide to Grasses of Southern Africa by Fritz van Oudtshoorn (Briza Publications). Contact Prof Noel van Rooyen on (012) 348 9043. |fw