Animal Trampling

Description: Effect of mechanical pressure on the soil, grasses and herbaceous cover as a result of trampling by herbivores. It is particularly effective in places where trampling is repeated: e.g. tracks, places around watering points, livestock resting sites. Wet soils, if malleable, are more susceptible to the affects of trampling than dry ones. Plants can be crushed or broken by the foots of animals. | Description Negative Effects Positive Effects Technology Options Policy Pressures and Policy Options

High animal densities and unevenly distributed stocking rates are causes of excessive trampling. Sub-humid and humid tropical countries are particularly susceptible to soil compaction because many of soils are rich in loam or clay, and the stability of soil structure is often weak.

Negative effects:
Superficial compaction of soil, assessed by the bulk density which is increasing, meanwhile porosity is decreasing.

Consequences :

- The speed of water infiltration is affected: water penetrates slowly into the soil, as shown by the level of moistening in the soil profile. As a result, less water is stored in the soil profile and in the water table. In regions suffering severe dry seasons, water deficit in compacted areas will have a greater impact on the production of biomass.

- Runoff increases: rainwater not absorbed by the soil flows on the ground and is finally drained by the rivers. An important runoff increases swelling hazard and modifies the stream flow patterns.

- Erosion: during runoff, the superficial flow develops an energy able to carry away the finest soil particles and organic matter. This erosion causes a loss of land, a loss of nutrients, the pollution of water by solids in suspension, sediment deposition in rivers and flood plains and changes in stream morphology. Erosion can cause severe loss of fertility when the superficial layer of soil is taken away.

- Plant establishment and growth: the roots of seedlings and young plants hardly penetrate into the soil and find poor water supply conditions. Plant cover is affected.

Positive effects:
Superficial crusting can develop on loamy or sandy soils when strong humidity alternates with drought. Crusting limits water infiltration and plant roots penetration. Animal trampling can remove this crusting, helping litter and seeds to be mixed with soil particles. Animal trampling can also be used as a mechanism for preparation of paddy fields.
Animal feet on grass tufts can stimulate tillering and rooting of stolons, improving the ground cover.

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