Soil erosion

Water management / Soil erosion

Soil erosion is the mechanical removal of soil by rainwater, which washes away the surface layers.

Soil erosion involves two soil degradation processes :

capping, which reduces water infiltration
erodibility, which reflects a soil's susceptibility to the removal and transport of particles by rain and run-off.

In the long term, erosion can lead to irreversible soil degradation. It is often reinforced by human action.

It poses a real problem for farmers : as well as causing gullies to form and the land to subside, it also leads to the loss of fertile elements contained in the soil, a deterioration in water quality and the displacement of sediments that form mudflows.

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Soil erosion risk in small agricultural areas

What can be done to limit soil erosion?

Agronomic measures

Planting crops perpendicular to the direction of the slope will reduce the intensity of runoff. Crop rows act as a physical barrier to water run-off.
Avoid soil compaction, which will limit water infiltration and increase run-off. To do this, you need to work the soil or use suitable equipment.
Once the soil has been worked, it should not be smooth, but lumpy and rough, to limit run-off.
Avoid ploughing, which leaves the soil bare to the mechanical action of rain.
Cover the soil with a mulch to provide a physical barrier to the action of the rain and avoid the "splash effect". This mulch can be natural (plant residues on the surface of the previous crop) or artificial (straw).
Plant intercrops. This will avoid having bare soil between two crops. They can play a beneficial role for the soil, such as trapping nitrates, having a structuring effect on the soil but also a fertilising effect and limiting weed pressure.
A well thought-out crop rotation will have an impact on the soil's resistance to run-off.

Creating barriers to run-off

Ponds and hillside reservoirs retain water and sediment. They form a water reserve that can be used at a later date.
Embankments slow down run-off and encourage infiltration.
Hedges, with their roots, encourage infiltration and water absorption.
Break up run-off paths with roads across the slope.
Install grassed strips at least 30 cm wide along the slope.
Ditches or drains will channel the water away from the plot.

Sources