Forage production of some grass species in the false Thornveld of the Eastern Cape

Abstract

The most commonly occurring grass species in the False Thornveld (Acocks, 1953; veld type no. 21) were clipped before and after grazing on veld in good and poor condition at different times of the year. Herbage yield per species was expressed per unit basal tuft area, and the difference in yield before and after grazing was considered to reflect the production of available forage. Themeda triandra produced more forage than any other species at all times of the year. Sporobolus fimbriatus generally produced the second highest amount of available forage. Cymbopogon plurinodis, despite having the second highest herbage yield before grazing, was not grazed to a significant extent. On the basis of the results, Themeda triandra and Sporobolus fimbriatus were identified as key grass species in the False Thornveld of the Eastern Cape.     

The effect of thirty years of burning on the Highland Sourveld of Natal

Abstract

A veld condition assessment was used to determine the effect of past burning treatments on the species composition of Highland Sourveld at Cathedral Peak. Veld condition scores in grassland protected from fire were significantly lower than where veld had been burnt or burnt and grazed at regular intervals. Frequent defoliation was found to maintain the grassland composition largely unchanged over a period of 30 years. Individual species were found to react strongly to defoliation frequency.     

Exploratory trials on reinforcement of veld with legumes in the south‐eastern transvaal highveld

Abstract

The feasibility and potential of reinforcing veld with legumes in the south‐eastern Transvaal highveld was assessed in a number of trials during the period 1974–84. Experience was gained with regard to methods of establishment, adaptation of legumes to the local environment, responses to fertilization, especially with lime and superphosphate, and the reaction of legumes to fire and grazing. In all, 17 legumes were involved, including the genera Coronilla, Desmodium, Glycine, Lespedeza, Lotus, Macroptilium, Medicago, Neoto‐nonia, Trifolium and Vigna. Only Coronilla varia (crownvetch) showed a satisfactory degree of persistence. However, crownvetch is slow to establish, is intolerant of waterlogging and has a relatively high requirement for lime and phosphate. Considering these features, and the probability of undesirable changes in grass species composition in reinforced veld, it is recommended that intensification be achieved through development of improved pastures for use in conjunction with veld, rather than by means of veld reinforcement.     

Influence of sowing depth on the germination of Karoo shrubs and grasses

Abstract

Knowledge of the germination behaviour of desirable plants to be sown in the veld for veld improvement is still inadequate. To gain this knowledge, seed of different species of Karoo bushes and grasses were planted on two soil types at different planting depths.

Germination percentage of all species tested were significantly lower when planted on the surface in sand as compared with depths of 10 and 20 mm. Germination percentages were also lower at the 0 to 2 mm planting depth than the 10 mm and 20 mm planting depths when planted in a sandy loam soil.     

An evaluation of veld condition assessment techniques in Highland Sourveld

An evaluation of six methods used to index veld condition showed that the majority provided indices that were insensitive to long‐term grazing impact. However, certain species were found to either increase or decrease in relative abundance with an increase in grazing intensity. A key species method is therefore suggested to be a potentially sensitive approach for indexing veld condition in relation to grazing management in the Highland Sourveld.     

Presidentielerede

Abstract

Present methods of evaluating veld composition in relation to grazing capacity can be criticised on grounds of subjectivity, especially with regard to the assignment of relative values to the constituent species. Data relating to botanical composition and estimated grazing capacity, derived from long‐term animal production systems trials, were used to examine the possibility of increasing objectivity. A “multiplier‐correlation” method involving four palatability classes was devised, which appears to provide valid estimates of the status of different species in term of grazing capacity. Multivariate analysis of the proportional species composition, classified into four palatability classes, provided confirmation of the validity of the multiplier‐correlation method.     

An evaluation of the economic viability of commercial pastoralism in the smaldeel area of the Eastern Cape

Abstract

Carrying capacity models and financial data from study group farmers were used to derive attainable net revenue per ha on veld in good, moderate and poor condition. From these data, minimum farm sizes required for a reasonable standard of living (R20 000 net personal income per annum) were estimated for each veld condition class. These minimum sizes were compared with actual farming unit sizes determined from a farm survey.

Most farming units are large enough to provide a reasonable standard of living, on condition that the farmer has little debt and does not have to incur costs of land development. However, most farmers cannot afford to implement the development required for currently recommended conservation practices. If conservation is required by society, subsidization of conservation practices should be considered.     

A comparative study of three veld types of the Northern Cape: Species evaluation and yield 1

A comparative study was undertaken of the grass component of the three main veld types of the Vryburg district; namely Sand veld, Dolomite veld and Lime veld. Results indicate that different species within the same veld type and the same species in different veld types differ in their dry matter production, digestibility and digestible organic matter production. Botanical composition and basal cover also varied between veld types. Veld types also differ in DM yields, digestibility and DOM yield.

The average digestibility of all species at three growth stages (leafy, flowering and mature) was 48,7% in sand veld, 54,8% in dolomite veld and 54,7% in lime veld. The average dry matter production and digestible organic matter production per m² at three growth stages were 2 083,9 g and 844,5 g in Sand veld, 2 108,6 g and 952,5 g Dolomite veld, and 1 776,0 g and 808,8 g in Lime veld, respectively. The possibility of deficiencies of Zn, Cu and P is indicated in all three veld types.

The percentage basal covers of sand veld, Dolomite veld and Lime veld were 4,3%, 2,1% and 5,0% respectively. The average DM yield and DOM yield of the veld types were 786,4 and 301,1 kg/ha in Sand veld, 403,9 and 189,2 kg/ha in Dolomite veld, and and 365,7 kg/ha in Lime veld respectively. The average digestibility of the veld types were 44,0%in Sand veld, 56,3% in Dolomite veld and 52,3% in Lime veld.     

Influence of stocking rate and grazing system on plant basal cover and botanical composition of veld in the northern cape 1

Abstract

Changes in basal cover and botanical composition were recorded at four stocking rates, both under continuous and rotational grazing in the Northern Cape. The experiment was conducted with cattle. Results suggested that heavier stocking rates could be applied under rotational grazing than under continuous grazing without veld deterioration occuring. After four seasons, botanical composition deteriorated only under continuous grazing. Plant basal cover decreased significantly at the heavy stocking rates, both under rotational and continuous grazing. This result illustrates the danger of grazing strategies based on an injudicious increase in stock numbers.

Basal cover was found to be a better indicator of trends in veld condition than botanical composition, despite annual fluctuations resulting from rainfall variability. Changes in the botanical composition apparently occur only where veld deterioration is more advanced.     

Korttermyn invloed van strawwe droogte op veldtoestand en waterverbruiksdoeltreffendheid van grasveld in die sentrale Oranje‐Vrystaat

Short‐term effect of severe drought on veld condition and water use efficiency of grassveld in the central Orange Free State. The impact of an intensive drought (1982/1983 and 1983/84‐growing seasons) on botanical composition, basal cover, mortality of grazing plants and water use efficiency (WUE) of veld in good, moderate and poor condition was identified. Increaser II species were apparently more capable of surviving drought than the Decreaser species. Under optimal soil moisture conditions the Decreaser species increased and the Increaser II species decreased. During the drought extensive grass mortality took place. Veld condition plays an important role in determining mortality during drought. Decreaser species have a high water requirement for optimal WUE, while Increaser II species can reach maximum WUE with less water. Under water stress conditions Increaser II species significantly (P≤0.01) do not use the water as efficiently as do Decreaser species. The WUE under water stress conditions for veld in good, moderate and poor condition was on average, during the study period, 0.90; 0.90 and 0.40 kg ha^?1 mm^?1, respectively, and towards under optimal water conditions, 2.47; 1.67 and 0.23 kg ha^?1 mm^?1, respectively.     

Exploring the potential of the descending‐point method to measure utilization in karoo veld

Abstract

The descending‐point method of vegetation survey proved effective in measuring meaningful plant cover changes during a grazing period. No significant changes in basal cover or plant height were detected. Changes in canopy spread and canopy cover could only be used to detect changes in utilization at levels lighter than 50 % and 70 % respectively. Selective utilization between species implies that it may be extremely difficult to achieve a specified level of utilization in practice. Therefore, in karoo veld, resting may be considered a more practicable veld management strategy than attempts to achieve a specific utilization intensity. The descending‐point method is time‐consuming in determining canopy cover. Thus, methods based on more effective point sampling, within the canopy spread, may be more appropriate for this purpose.     

A consideration of veld condition assessment techniques for commercial livestock production in South Africa

Abstract

A number of procedures have been developed for the evaluation of veld condition in a variety of vegetation types in South Africa. These include both agronomic and ecologically based methods, about which there still remain a great deal of controversy. However, the urgent need for methods which can be applied in practice has recently prompted the recommendation of specific methods for the vegetation types representative of the major livestock producing areas of South Africa.     

Research note: Grazing‐index method procedures of vegetation surveys

Abstract

In the past, veld condition in the Karoo was assessed using the ecological index method. This recently changed to the grazing‐index method on account of the differently estimated grazing‐index values being used. The principles governing the method of survey remain the same. The method employs canopy‐spread‐cover strikes to record the species composition of different sites. By appropriate management of these line‐point data, different sites can be compared with one another by employing the Z‐index of agreement (similarity).     

The effect of severe drought and management after drought on the mortality and recovery of semi‐arid grassveld

Abstract

The False Thornveld of the Eastern Cape experienced a particularly intense drought during the 1982/83 growing season. Extensive grass mortality took place during the drought. After the drought, recovery was particularly sensitive to the post‐drought management treatment applied. Veld that was grazed immediately after the drought recovered far more slowly than veld that was rested. This effect was still evident three years later, illustrating the considerable importance of resting semi‐arid grassveld after a drought.

Increaser I grass species present were apparently more capable of surviving drought than the Decreaser species, which in turn were more stable than the Increaser II species. Their ability to recover after the drought followed an opposite trend. On this basis, the desirability of Decreaser dominated veld, in situations that are likely to be poorly managed, is questioned.     

Effect of slope and plant cover on run‐off,soil loss and water use efficiency of natural veld

Abstract

Run‐off and soil loss were monitored from a climax, subclimax and pioneer veld, each on a 5,9%, 4,1% and 2,1% slope, by means of a rainfall simulator on a Valsrivier soil form. With rainfall intensity, soil moisture content at the beginning of each rain storm, and soil texture the same for each treatment, plant cover and composition had a significant (positive) (P≤0,05) influence on the amount of soil loss and run‐off that occurred, as against the insignificant influence of the slope.

An average of 6,2 t/ha soil loss and 80,6% run‐off of the amount of water applied occurred from the pioneer veld (0,7% basal cover) on the steepest slope. In all the successional stages more run‐off and less soil loss occurred from wet soil than from dry soil. Significant (P≤0,01) relationships between basal and canopy cover were obtained with run‐off and soil loss.

The climax, subclimax and pioneer veld produced on average 0,57 g, 0,23 g and 0,07 g aboveground phytomass for each litre of water evapotranspirated.     

The effect of veld condition on the quality of diet selected by cattle grazing the Natal Sour Sandveld

The quality of diet selected by steers fistulated at the oesophagous was related to veld condition in a simulated rotational grazing system on the Natal Sour Sandveld. Six camps, ranging in veld condition score from 8,5 to 53%, were grazed simultaneously for a two‐week period in spring, summer, autumn and winter. Fistula samples were collected on the first, middle and last day of a period of occupation in a camp. Samples were analysed in terms of crude protein (CP), in vitro digestibility (IVD) and plant‐part (% leaf, % stem and % dead material) composition. Dietary quality in terms of CP, IVD and plant‐part composition was not related to veld condition but was dependent largely (P≤0,01) upon season and to a lesser extent upon period of occupation in a camp. It was concluded that in sourveld areas, where dietary quality may be limiting, the veld condition score may be a poor index of potential animal production.     

Interrelationships between veld condition,herbage mass,stocking rate and animal performance in the Tall Grassland of Natal

Grazing trials were established at three sites in the Tall Grassveld of Natal. The objectives were to determine (a) patterns in herbage mass in relation to veld condition, stocking rate and commencement of spring grazing, and (b) animal performance in relation to herbage availability and stocking rate for the period November 1986 to September 1987. Rainfall exceeded the mean annual rainfall and, for moderate condition veld in particular, was very favourably distributed. Distinct patterns in herbage availability were seen during the season. A multiple linear regression model was developed for determining peak herbage mass (HM) in April from veld condition (VCI), stocking rate (SR) and time that grazing commenced in spring (T) (r=0,71; P<0,01). HM was positively related to VCI and delayed T and negatively related to SR. Seasonal growth phases in cattle were similar for different sites despite their spatial separation and differences in veld condition. It was essentially only the magnitude of mass loss or gain that varied. No linear relationships existed between SR and average daily gain (ADG). A multiple linear regression model was developed for determining ADG from SR, HM and the initial mass of the animals (IM) (r=0,93; P<0,01). ADG was positively related to IM and negatively related to SR and HM.     

Development of veld management research in the karoo region

The development of veld research in the semi‐arid Karoo areas since 1934 is outlined. It entailed key experiments on different types of veld, and the synthesis of grazing systems and their testing in experimental camps and co‐operatively on a practical farming scale. The experiments were primarily conducted with Merino sheep but Angora goats, Boer goats, cattle and Persian sheep were also employed. A large number of rotational grazing systems, special treatments and methods have been set out for the entire Karoo Region. The group camp approach serves as a basis for complete veld management planning in the Karoo Region.

Supporting research covered plant physiological, phenological and ecological studies; the determination of selective grazing habits of livestock; production of karoo bushes; and the development of research techniques especially in connection with quantitative and qualitative vegetation surveys.     

Veld condition in the south‐eastern Transvaal and its effect on grazing capacity

Abstract

A survey conducted on sites throughout the south‐eastern Transvaal, representing 1,4 million hectares of natural veld has confirmed the parlous state of composition, cover and vigour. The implications which these conditions hold, not only for conservation of soil and water resources, but also for the livestock industry in this area, with specific reference to the current grazing capacity of the veld, are discussed.     

Towards a plant‐based technique to measure utilization of karoo bushes

Abstract

The precision of various destructive techniques for estimating utilization of karoo bushes was investigated with the prerequisite that removal of 20 % of the edible material of individual species could be shown to be statistically significant. Where the total mass of destructively‐sampled plants was compared, a sample of 300 plants/species was required for this level of precision. In contrast, only 100 plants/species were required when utilization was based on edible phytomass. The sparseness of karoo veld renders the destructive sampling of areas less efficient than clipping individual plants. However, sampling of whole plants and their separation into edible and inedible fractions is laborious and expensive. There is thus a need to develop suitable nondestructive techniques.