Holistic Bush Control Initiatives to Salvage Livestock Production from Bush Encroachment in Southern Africa

Dr Nyasha John Kavhiza

 

In Namibia, Botswana, parts of South Africa and parts of Mozambique vigorous bush encroachment in the rangelands has adversely impacted livestock production and if swift decisive action is not taken, a lot of livestock farmers will be forced out of business, threatening food security in the Southern African region. As the rangelands are taken over by the bushy species our prospects of having either beef or milk dwindle and so do the incomes of the
households directly or indirectly dependent on the livestock industry.

Having the feedlot system as an alternative is of limited practicability since this method of production is very expensive and requires a lot of expertise, hence not applicable to most farmers in the region, particularly the communal and/or smallholder farmers. In simple terms the rangelands have to be prioritized for continual development of the livestock production sector, thus the need for proper bush control initiatives.

The bush species (Acacia, Mopane, etc.) invading these rangelands are not exotic plant species as such, rather they are indigenous species whose numbers (density) are now threatening existence of other plant species especially the grasses which the cattle feed upon. With this understanding it is important to note that the aim of bush control is not to totally eradicate the bush species but attain optimum levels necessary for a balanced ecosystem.

Anthropogenic activities as well as shifting climatic patterns have had synergistic effects which lead to the proliferation of bush encroachment. The erection of fences on the farms has meant the exclusion of natural browsers (wildlife) such as the kudu, eland, impala, waterbuck, etc. which feed on the leaves and barks of the bushy species. Therefore, the bushes continue to grow vigorously whereas in the absence of fences the natural browsers would keep the density of the bushes at sustainable levels. The exclusion of occasional fires on the farms also leads to the
vigorous proliferation of the bushes. Natural wildfires serve as mechanisms of balancing out the ecosystem, however in the ranges where livestock is reared the conditions are modified such that occasional occurrence of the fires is dramatically reduced, giving an opportunity for the bushes to thrive. In the event of an occasional fire the slow recovery of the woody bush species gives an advantage to the grass species which recover quickly.

Some emerging research highlights that occasionally using fire as a control method especially when the bushes have just sprouted and they are in their most vulnerable vegetative stages can be effective. The timing of carrying out the control operations should coincide with high air temperature and low humidity so as to increase efficiency in burning the bushes. However, for long term control the method should be complemented by practices such as maintaining low stocking rates and providing fire refugia for wildlife. Overstocking of the livestock leads to overgrazing thus depleting the grass species allowing massive germination of the bushy plants. The existence of the grassy plains interferes with the successful germination and seedling survival of the bushes whereas in the absence of grass the seedlings of the woody bushes are well established.

Once the bushes have encroached the space they then “smoother” the grasses competing against them for resources such as water, sunlight, air and nutrients. Moreover, these bushes have high competitive ability since they are broad-leaved plants. Therefore, the grasses disappear, leading to degradation of the rangelands. The bushes also interfere with the recharging of the water table in these semi-arid to arid areas, as they have higher transpiration rates than grass species which are narrow-leaved.

This naturally increases the area’s rate of evapotranspiration, hence depleting the water table. Consequently, this creates the problem of a lack of feed as well as water for the livestock causing the animals to be famished and degrading their condition. This kicks the livestock farmers out of business, especially those running small-scale operations. This therefore calls for holistic and environmentally sustainable bush control initiatives in the Southern African region. However, this is not an inexpensive undertaking.

A range of approaches are currently being employed to control the bushes on the rangelands. Aerial application of aboricides with aircraft has high negative environmental impacts, while it controls the bushes, the problem is that most of these chemicals are non-selective, hence they also kill non-target tree species such as the Mukwa and teak which are highly valuable.

The use of drones may lessen the problems associated with this method they allow for site-specific application and can compute how much aboricide to apply for each particular bush through the variable rate technology. Having said that, some risk still remains since the tree root systems can be linked in the Savannah ecosystem thus leading to the transmission of the aboricide via the roots. Some farmers are applying mechanical methods to reclaim their rangelands from the bushes. They use bulldozers to remove the bushes whilst others use chainsaws and axes. This is labour intensive and also consumes a lot of resources.

To justify the high costs associated with bush control whilst being environmentally conscious, some farmers have started processing the destroyed bushes into products of higher value. Some are transforming the bushes into braai (barbeque) charcoal and charcoal briquettes in Namibia. Bushes are generally small and their twigs can easily be compressed to make charcoal briquettes. Namibian charcoal imports are on the rise with the country importing 59 350 tons worth US$85 710 in 2022and 113 620 tons valued at US$102 360 in 2023. Therefore, the charcoal produced from the debushing exercises has a ready market and this also aids in recouping the costs incurred in the bush control process.

Others are transforming the bushes into biochar which is used in horticulture or market gardening. Some enterprises have been set up across the region to process the bushes into this product which is an important integral part of organic farming. This biochar is mainly incorporated in the soil to increase fertility as well as water retention capacity for a very long time. However, it is important to inoculate the biochar with microorganisms and nutrients so that it does not take them from the soil, arresting them from the plants. Most biochar manufacturers for the horticulture market mix the processed biochar with livestock manure, particularly cattle manure as well as whey from dairy processing as these two substances contain a lot of nutrients as well as microorganisms. This makes the biochar stable and suitable for incorporation into the soil, thus improving fertility and crop yields consequently.

As droughts are becoming more frequent, some farmers in the region have started experimenting with processing the bushes into livestock feed. They harvest the bushes when they are young and whilst they are green, then mill them into palatable fiber which they mix with molasses, urea, salt, a bit of water and 10% maize, thus the livestock can be maintained on this diet. The bushes have to be harvested young because they can easily be milled and most importantly, they contain very low levels of tannins (toxic to livestock at high concentrations), hence suitable for feed production.

Goats can form part of the solution in the bush control struggle. Though goats can feed on grass they are generally browsers, preferring leaves and barks of woody plants (shrubs and bushes). Releasing the goats into bush-infested areas can be effective in controlling the invasive tendencies of these plant species. This method has been tried in Australia, parts of Europe and America, proven to be effective. The goats strip the bushes of their leaves, impairing the photosynthesis rate of theses plants thus interrupting their growth, leading to plant death, allowing the grass species to reestablish and reclaim the rangelands. Moreover, the goats produce manure which they deposit on the rangelands, thus improving soil fertility.

The synergistic efforts from all these approaches forms a holistic system in which the bushes can be effectively controlled on the rangelands of the region. As scientifically proven optimal debushing increases rangeland area which is correlated with higher farm incomes. This therefore fosters the continual development of the livestock sector in the region, thus ensuring food security in Southern Africa.

 

 

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Dr Nyasha John Kavhiza (PhD) is a well-seasoned agriculturalist and environmentalist with extensive understanding of the African region and plays some key consultative roles in the industry. He writes in his capacity and can be reached at njkavhiza@rocketmail.com