Risk Overview:
Mixed Communal Grazing

Below are presented the principal positive LxE (+) and negative LxE (-) impacts of livestock on the environment. An overview of Risks and Opportunities for each is presented in the Risk Matrix Mixed Communal Grazing

LxE (+)

The principal positive impacts are:

- contribution of livestock to sustainable crop cultivation through manure production.
In general the number of Tropical Livestock Units per ha of cropland is not sufficient to produce enough manure for permanent crop cultivation.
- Strong environment-genotype interaction. As a result this system produces and maintains a large share of the world’s genetic bio diversity in domesticated species: goats, sheep, cattle, buffalo, camels, donkeys, horses, yaks, llamas, alpaca and other rare species.

NB It is assumed that crop residues in this system are grazed and that manure (faeces and urine) produced is deposited in the crop fields. When crop residues are collected and fed at the farm the subsystem has evolved into a "Crop Residue System" and one should proceed from there.

LxE (-)

The principal potential negative impacts are:

- transfer of plant nutrients from communal land to cropland. This can result in a depletion of soil fertility and a lower production potential of communal land
- potential of overgrazing of communal pastures. This can result in a change of composition of the vegetation from palatable towards less palatable and annual species
- expansion of grazing (and burning) to marginal areas (hill slopes) or forests and protected areas (gallery forests, water conservation area, wild life parks etc.)

Note:

Livestock are often blamed for degradation of the environment that is caused by other users.

A general pattern in the exploitation of new land is that "waste land" or forests are first burned and grazed. Successive grazing and burning will change the tree - bush vegetation into a tree - grass vegetation. This opens ways for the harvesting of (fire) wood (charcoal burning) followed by cleaning the land for crop cultivation. After a number of years of cultivated land is left fallow or abandoned because soil fertility has dropped and land has become vulnerable to erosion and degradation. When livestock are grazing this fallow it can easily be blamed for all the degradation while in fact intensive wood harvesting, the cleaning of land and repeated crop cultivation in earlier phases have contributed more to the degradation.

Grazing of fallow vegetation can stimulate the rehabilitation of the vegetation cover and composition (cycling of nutrients and spreading of seeds). In general the density of palatable species on fallow land is low. Therefore they are often grazed by sheep and browsed by goats. Their selective grazing behaviour can result in a delay or even inhibit further regeneration of the vegetation. This can be a desired result when the objective of farmers is to cultivate the fields again after a couple of years of fallow. If the objective is to rehabilitate degraded land through natural regeneration or reforestation, the grazing by cattle and sheep and the browsing by goats of these areas become issues for local level management and control.

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