Soil erosion is the removal of soil components by run-off water, wind, snow-melt or soil shifting. Much of it is due to human activity. The loss of topsoil is a major problem because soils lose their most fertile and therefore agriculturally important part.
The impact of raindrops on topsoil destroys the solid soil aggregates. The soil particles loosened in the process are rearranged and compacted, which is known as surface silting. If the slope is steep and precipitation persists – as little as 5 litres per square meter per hour – loosened soil particles are now transported with the surface run-off and redeposited elsewhere. Arable land with slopes and soils rich in silt and fine sand, without protective plant cover, is particularly susceptible to water erosion. For example, conventionally tilled fields of silt-rich Loess soil, are at high risk of erosion immediately after seedbed preparation, until a protective plant cover is formed.
In wind erosion, larger and smaller soil particles are carried from the soil surface by the wind, sometimes over long distances. Particularly affected by this, are areas that are open to the wind, dry, and very flat surface, with a high proportion of fine sand. Here too, as in the case of water erosion, extensive, conventionally cultivated arable land is considered to be particularly at risk in the period after seedbed preparation, until the protective plant cover has grown up.
Potential damages from water and wind erosion include:
- Shortening of soil profiles.
- Impoverishment of humus and fine soil particles.
- Impairment of soil function.
- Injury, up-rooting and destruction of cultivated plants.
- Washing away of seeds, fertilisers and pesticides.
- Input of sediments, nutrients and pollutants into water bodies.
- Pollution of traffic routes, settlement areas and ditches.
What are the consequences of erosion for agricultural management?
The damage caused by wind or water erosion, results in the loss of a lot of fertile soil – and thus, in the long term, the production basis for our food. There may be reduced yields and crop failures as a result of the loss of the plants themselves, as well as the loss of fertilisers and pesticides. The soil’s function as a filter is also disrupted, and water storage can be significantly impaired.
Measures of prevention – only precaution is possible!
- Erosion-reducing tillage and cultivation methods, e.g. mulch sowing without seedbed preparation if possible, conservation tillage with mulch sowing throughout the crop rotation.
- Erosion-reducing field design, e.g. creation of parallel strips at right angles to the slope with alternation of the crop type, or sowing of runoff-reducing grass strips; subdivision of the field by creating erosion protection strips (copses, field margins, corridor elements).
- Avoidance of downslope ruts.
- Avoidance or elimination of soil compaction.
- Minimise periods without protective ground cover through crop rotation design, inter-cropping, under-sowing, or the application of straw mulch.
- Generally build and maintain siltation-reducing stable soil aggregates, by promoting biological activity as well as liming.
Soil erosion control not only avoids erosion of fertile soil, and thus protects the soil itself. By reducing soil erosion, protection of watercourses and retention basins from increased silt loads, and thus from pollutant and excessive nutrient inputs is achieved at the same time.