Namibian rangelands offer a diverse range of forage resources for both livestock and wildlife. These plant groups include grass, trees, bushes and forbs utilised by both grazing and browsing animals. Grass, however, is the primary feed base for grazing livestock in Namibia.
The abundance of the most valuable grass species in many parts of the country has declined, resulting in reduced grazing value and lower carrying capacities for most grazing lands. Consequently, livestock production and potential income have been negatively affected.
The disappearance of the most valuable grasses can be attributed to selective grazing pressure from livestock, which compromises their establishment and their ability to compete for survival.
This gives rise to the opportunistic invasion of grazing lands by the least desirable plant species, including grasses such as Aristida stipitata and other shrub species such as Senegalia mellifera (Blackthorn), among others. In addition, overgrazing exposes the soil to erosion and heavy trampling, resulting in poor rangeland productivity, a condition further exacerbated by the country’s erratic rainfall patterns.
The grazing value of an area is determined by the grass species composition and their abundance over the grazing land. Two types of grasses can be distinguished in terms of life cycles or life span: these are annual and perennial grasses. An annual grass (e.g. Eragrostis porosa, Tragus berternianus, etc.) is mainly the first grass type to emerge in abundance after the first rainfall showers, and thus, the first green food for grazing animals after the dry season.
Annual grasses have shallow root systems, few leaves, and require minimal moisture, nutrients, and sunlight.
Moreover, annual grasses grow and produce seeds fast, but survive only during the rainy season and die at the onset of winter. The next annual grass will grow only from seed.
In contrast, perennial grasses such as Stipagrostis uniplumis, Eragrostis rigidior, and others have deep root systems, large leaf tissues, and require substantial investment of moisture, nutrients, and sunlight; thus, they take longer (about 2-3 months) to reach maturity.
Perennial grasses constitute the bulk of the grazing animal’s diet throughout the year. At the end of the rainy season, perennial grasses do not die but go into dormancy for the whole dry season.
They shed seeds and store nutrients in their stump as food reserves for the next season’s growth. The same dormant grass stump will produce fresh/new stems and leaves, and the seeds will germinate into new grasses (seedlings).
Furthermore, these grasses shed seeds as they start to dry up (in the dry season, from May). These seeds may be found in soil collected from ditches. In August, the wind distributes and buries (sowing) them, and when rainfall (watering) begins, germination commences.
To restore grazing lands and produce their own fodder, farmers need to reintroduce valuable perennial grasses through reseeding. These grasses include Cenchrus ciliaris (Blue buffalo grass) and Anthephora pubescens (wool grass), amongst others. They can be cultivated in fields as food crops and also planted in grazing areas.
The seeds can be harvested from standing, dry grass or purchased from standard agricultural input suppliers such as Agri-gro and Agra, among others. It is very important that cultivated grasses are protected from disturbance (grazing) and are allowed to grow to maturity until they produce seeds and can regenerate themselves.
Once harvested, such grasses can be processed into hay or milled and mixed with other feedstuffs and used or stored for periods of fodder scarcity.
*Erastus Ngaruka is Agribank’s Technical Advisor for Livestock & Rangeland.