Last update: April 10, 2012 10:05:14 AM E-mail Print

 

Veld Management in the Karoo

C. E. Tidmarsh 


IT is generally recognised that, apart from the more obvious mechanical measures for the gully erosion, soil conservation in the Karoo resolves itself essentially into an endeavour to conserve and maintain the natural veld at as high a level .of soil cover and productivity as the existing conditions of climate permit. Granted that the general condition of the veld at present is far from satisfactory, the problem is much simpler to state than to solve, and while it may be fascinating to rationalise and speculate about what should be done to conserve this vast natural resource, it must constantly be borne in mind that, in relation to the country's surface, the financial resources of the nation are rather small, and that in view, therefore, of the nation's commitments in terms of the Soil Conservation Act, and the vast sums that can easily be expended in the course of conservation efforts, a heavy responsibility rests on all those concerned to recommend and apply only those measures that will be reasonably assured of achieving the desired results.

In respect of this stipulation, the position in the Karoo relative to the present state of knowledge leaves little room for satisfaction. In all that vast country, composed of several great and distinct regions, at one point only, at the Grootfontein College of Agriculture, is any carefully controlled and critical research on the many problems of the veld being undertaken. Although these researches are being extended by means of cooperative experiments to different parts of the region (eastern Mixed Karoo or False Karoo) served by the College, the findings of these researches, except in fundamental principle, will probably not have direct application to the other, more arid, regions of the Karoo.

The results of the past seventeen years of research lit the College have shown clearly that the amount of natural vegetation that can be maintained per morgen of land, is controlled more by the available moisture supply than by the grazing treatment to which the veld may be subjected, and that in the extensive flats of the Mixed Karoo, the quantity of vegetation growing at present on the soil is with the exception of local areas of denuded soil, in approximate equilibrium with the available moisture supply, and that, without increasing the latter, it is virtually impossible to increase the natural cover of the soil by any measure of grazing control, including complete protection. Experiments in those flats have also shown that by the application of extremely heavy stocking rates on the one hand, and complete protection, on the other, significant differences in the composition and quality of the veld can be produced, but that, within the range of treatments that can be applied in farming practice, no lasting change in the composition of the veld i.e. in the relative proportions of the different kinds of plants -palatable and unpalatable, can be produced. Within limits, the composition of the veld appears, thus, to be more a function of the interaction of the soil type, moisture supply, and climate, than of grazing treatment. Furthermore, it has been found that, in the systems of grazing-rotation tested, the more the sheep were concentrated in smaller camps, for shorter periods, the less they produced in mutton and wool. In this respect, continuous grazing, at a moderate rate of stocking, furnished satisfactory results. These findings are in accord with those of various investigators in the United States of America.

For several reasons, however, continuous grazing, even at a light rate of stocking, cannot be recommended for application in the Karoo. In farming practice, try as one might, it is virtually impossible, with variable topography and limited water supplies, to separate into different practical camps all the different types of veld on the farm in such a way that each camp will contain only one homogeneous type of veld. Since every camp is thus bound to contain areas of more palatable veld and areas that are less palatable, with continuous grazing, area selection will inevitably result. The more palatable areas, particularly if they are relatively small, will, by continually repeated grazing and withdrawal, tend to become denuded and will serve as the starting points for erosion. Similarly, other areas of concentration of stock, at drinking points and sleeping places, will become trampled bare, and well defined footpaths between such areas will develop. These conditions are prevalent in the Karoo at present.

The goal of veld management in the flats of the Mixed Karoo must therefore be to obtain as high a production of animal produce as that furnished by continuous grazing, and at the same time to obviate the deleterious effects on the veld of that grazing practice. Since, however, this approach is rather negative, in that a marked improvement in the overall composition and quantity of the veld is not expected of it, the most simple and least costly grazing system that will fulfil the requirements must be sought.

Of the numerous systems tested at the College, the simple Z-camp system, set out below, has proved from the points of view mentioned, to be the most satisfactory, and may be recommended provisionally for the flats until such time at least as further research should provide a more suitable system with which to replace it.


Camps

1st year

2nd year

 

SP

SU

AU

WI

SP

SU

AU

WI

1

GG

-

GG

GG*

-

GG

-

GG

2

-

GG

-

GG

GG

-

GG

GG*

 

GG = Graze

GG* = Graze last month of winter

SP = Spring

SU = Summer

AU = Autumn

WI = Winter

 

Researches on the veld of mountains, hills and vleis in the Mixed Karoo have furnished results different from those in the flats. These researches have shown that, when accorded lenient treatment, mountains, hills and vleis, due to their more favourable moisture relations, exhibit a strong tendency to develop different types of nutritious grassveld. Since vleis are usually rather small in relation to the other grazing areas of the farm, they should preferably be reserved for special purposes, and rested as much as possible during the summer months. If sufficiently large, mountains and hills should be fenced separately, and a system of grassveld management applied to them.

A comprehensive report on the past sixteen years of veld researches at the Grootfontein College of Agriculture will become available in due course. 

 

Published

Farming in South Africa 27