agricultural production guidelines
m
Veld in KwaZulu-Natal
Co-ordinated Extension KwaZulu-Natal Veld 4.5 1999
BIORESOURCE GROUPS 8 & 9 : MOIST AND DRY HIGHLAND SOURVELD
M B Hardy
Western Cape Department of Agriculture
Vegetable
Structure and Composition
Veld Benchmark
Animal Production
INTRODUCTION
Bioresource Groups 8 and 9 are generally referred to as Highland Sourveld. These BRG’s occupy the high-lying western and central portion of KwaZulu-Natal (refer to Figure 1 in Production Guideline 4.1 in this series). The region comprises the foothills and eastern slopes of the Drakensberg range, from Kokstad in the south to Charlestown in the north. Areas of Highland Sourveld also occur in isolated high-lying plateau areas in central KwaZulu-Natal (e.g. Helpmekaar, Qudeni, Babanango and Mahlabatini).
The Highland Sourveld may be divided, according to rainfall, into moist (BRG 8) and dry (BRG 9) regions. Exact boundaries are difficult to delineate. Generally, the drier regions occur in the east Griqualand and Newcastle areas.
The mean annual rainfall in the drier regions of the Highland Sourveld is approximately 150 mm less than that of the moist region. In the drier regions, rainfall is less reliable and the rains start later in the year. Subsequently, grass growth may be delayed until October, while in the moist regions grass growth normally commences during September. This results in a lower dry matter production, and therefore a lower grazing capacity, than the moister regions of the Highland Sourveld.
VEGETATION STRUCTURE AND COMPOSITION
The vegetation in BRG’s 8 and 9 may be described as a low, closed grassland, with the grasses seldom reaching a height in excess of 0.5 m. Fire has played a major role in maintaining the area as a grassland which, in the absence of fire, would become dominated by shrubs and bushes and, in certain cases, progress to tall evergreen forests. Grazing also plays a role here, and it is through the interacting effects of fire and grazing that the Highland Sourveld remains a grassland suited to extensive livestock production. However, the incorrect use of fire, and poor grazing practices, often reduce the livestock production potential of the veld.
Grassveld with the composition given in the benchmark (Table 1) is considered to be in optimum condition for animal production, and may be used in a similar ecological zone as a reference point against which another sample of grassveld may be compared. Although the botanical composition varies considerably, predominance of Themeda triandra (redgrass) is taken to indicate that the veld is in good condition.
Where the veld has been heavily grazed, species such as Eragrostis curvula, E. plana and Sporobolus africanus (the mtshiki grasses) tend to increase in abundance and replace species such as redgrass and Tristachya leucothrix (tridentgrass). Since the mtshiki grasses tend to be less palatable and productive than the grasses that they have replaced, the grazing capacity of the veld is reduced. In addition, the length of the grazing season is reduced (i.e. the veld becomes more sour). With selective grazing e.g. Diheteropogon filifolius, Elionurus muticus (the wiregrasses) increase in abundance and again reduce the overall production potential of the grassveld.
Fire plays an important role in determining the structure of the vegetation in these Bioresource Groups (refer to Production Guideline 7.5 in this series). Where fire is totally excluded from the system, shrubs and bushes begin to make an appearance, particularly in the cooler, moister areas (e.g. south-facing slopes and along stream beds). Common species which may become a problem include typical forest precursor species such as Leucosidea sericea (ouhout), Buddleja salviifolia (sagewood) and Rhus species.
Extensive forest patches in the Highland Sourveld are usually found on the moister south-facing slopes. Common trees in these forests include Podocarpus species (the yellowoods), Olinia emarginata (mountain olinia), Diospyros whyteana (bladder nut), Calodendrum capense (Cape chestnut) and Celtis africana (white stinkwood) among others.
Highland Sourveld considered to be in good condition (with respect to a stable fodder-production potential) would be expected to have the species composition presented in Table 1. Table 1 also presents grass species which occur in these Bioresource Groups, but are not necessarily found in the benchmark. The species groupings (i.e. Increaser and Decreaser species), and concepts related to this classification, are explained in detail in Production Guidelines 6.1 to 6.3 in this series.
Abundances of other key grass species may be used in conjunction with redgrass to determine veld condition using the Weighted Key Species method (refer to Production Guideline 6.2 in this series for a description of this method). These key species and their weightings are presented in Table 2.
Grass growth is rapid in spring and early summer. During this rapid growth phase, the grass tends to be highly nutritious and palatable to livestock, but as the grasses mature, they lose their nutritive value and become less palatable. This process generally starts at the beginning of February, and it is therefore essential that good-quality licks are supplied to livestock at this time of the year to ensure continued gain in animal mass. By June, the quality of the grass is so low that few classes of animals would be able to maintain mass, even when supplied with a good-quality lick. Only those animals with the lowest nutritional requirements remain on the veld during winter (e.g. hamels).
For these reasons, these Bioresource Groups are considered to be sourveld, which provides forage for only six to eight months of the year. Despite the relatively short grazing season, Highland Sourveld has a high livestock production potential, and many breeds of cattle are well adapted to the area. Dairy cows do not produce well due to the rapid fall in the quality of veld as the season progresses.
In spring and early summer, however, live mass gains of growing animals (e.g. heifers and steers) can be as high as 1 kg/day, provided that sufficient grazing is available. The Highland Sourveld is also an important beef-breeding area, where spring-born calves are weaned in autumn at between 180 and 220 kg.
In the drier regions (e.g. East Griqualand), the wooled Merino has been the most common sheep breed. However, during the past decade other breeds, better adapted to the moist grassland conditions, have been introduced on a large scale throughout the Highland Sourveld. Veld management practices applied to maintain the grassland for optimal sheep performance often result in the deterioration of the veld. Examples of these practices include:
burning the veld in winter (end of July or early August) and grazing with sheep as soon as regrowth commences; and
burning the veld in late summer/early autumn to provide "out of season" regrowth for ewes and their lambs during autumn and winter.
Both these practices lead to a general decline in species composition, and thus the livestock production potential of the veld. Where sheep are used they should be grazed together with cattle at a ratio of not less than one Animal Unit (AU) of cattle to each AU of sheep. This generally means that a maximum of 5 to 6 mature sheep could be grazed together with one mature head of cattle. The cattle are usually less selective, and remove the bulky material that is usually avoided by sheep. The grass is therefore maintained in a short condition, which is better suited to sheep grazing. With judicious management, the Highland Sourveld has the potential to be extremely productive.
VELD MANAGEMENT NORMS AND GENERAL INFORMATION FOR BRG’s 8 & 9: MOIST AND DRY HIGHLAND SOURVELD
BRG 8
BRG 9
Total area (1 000 ha)
Area of veld (1 000 ha)
Potential grazing capacity (ha/AU)
Current grazing capacity (ha/AU)
Grazing season (days)
Grazing cycle (days)
Period of stay (days)
Period of absence (days)
AU grazing days per hectare
Expected intake (kg/AU/annum)
Livestock production potential (kg livemass per ha/annum)
Excellent condition veld (90%)
Moderate condition veld (60%)
Poor condition veld (30%)
833
622
1.5
2.0
250
30
10
20
166
2 500
78
52
26
356
295
1.7
2.2
250
30
10
20
151
2 500
61
41
20
Rested area
Each camp should be rested once every four years
Winter grazing
Licks are required when grazing rested veld in winter. Supplementary feeding of hay and silage is also required during winter
Animal types
Cattle (high potential); Sheep (moderate potential); Goats (low potential)
Burning
Burn to remove moribund and excess herbage
1 In areas where stocking rates are higher than those given for potential grazing capacity, the livestock production potential will not be achieved. This is particularly so where continuous grazing is practiced.
2 Current grazing capacity is based on the average condition of veld in the BRG as estimated in 1997.
3 Animal Unit (AU) grazing days per hectare are based on the estimated average CGC of the BRG.
4 Livestock production potential refers to the expected amount of live mass (kg) gain per hectare using a beef weaner production system (see the example of such a system in Production Guideline 2.6).
Table 1. Benchmark species abundances and species not occurring in the benchmark for grassland in the Highland Sourveld (BRG’s 8 & 9).
Scientific name
Common name
Relative abundance (%)
BRG 8
BRG 9
Increaser Ib
Cymbopogon validus
Miscanthus capensis
Giant turpentine grass
East-coast broomgrass
Increaser Ia
Alloteropsis semialata
Cymbopogon excavatus
Digitaria diagonalis
Digitaria tricholaenoides
Eulalia villosa
Setaria nigrirostris
Trachypogon spicatus
Tristachya leucothrix
Blackseed grass
Common turpentine grass
Brownseed finger grass
Purple finger grass
Golden velvetgrass
Large seed setaria
Giant speargrass
Tridentgrass
2
1
2
20
1
1
1
20
Decreaser
Andropogon appendiculatus
Andropogon schirensis
Bracharia serrata
Diheteropogon amplectens
Monocymbium ceresiiforme
Themeda triandra
Bluegrass
Velvet signalgrass
Broadleaved bluestem
Wild oatgrass
Redgrass, rooigras
1
1
2
45
1
1
50
Increaser IIa
Eragrostis capensis
Harpochloa falx
Heteropogon contortus
Heartseed lovegrass
Catterpillar grass
Speargrass
1
3
4
1
1
5
Increaser IIb
Eragrostis curvula
Eragrostis plana
Eragrostis racemosa
Hyparrhenia hirta
Setaria sphacelata
Sporobolus africanus
Weeping lovegrass
Fan lovegrass
Narrow-heart lovegrass
Common thatchgrass
Golden setaria
Ratstail dropseed
1
1
1
1
1
1
2
1
Increaser IIc
Microchloa caffra
Paspalum scrobiculatum
Forbs
Sedges
Pincushion grass
Veld paspalum
1
5
1
1
4
2
Increaser III
Aristida junciformis
Digitaria setifolia
Diheteropogon filifolius
Elionurus muticus
Rendlia altera
Ngongoni
Fineleafed finger grass
Wire bluestem
Wire lemongrass
Toothbrush grass
2
5
1
4
1
Table 2. Key grass species and species weightings for grassland in the Highland Sourveld (BRG’s 8 & 9).
Scientific name
Common name
Species weighting
Paspalum scrobiculatum
Sporobolus africanus
Hyparrhenia hirta
Eragrostis plana
Eragrostis curvula
Heteropogon contortus
Themeda triandra
Tristachya leucothrix
Veld paspalum
Ratstail dropseed
Common thatchgrass
Fan lovegrass
Weeping lovegrass
Speargrass
Redgrass, rooigras
Tridentgrass
1
2
3
3
4
6
9
10
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