Human impact on soils
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Human impact on soils
The main issue is that soils take thousands of years to develop but are very quickly ruined by human actions. Natural loss occurs via leaching, erosion and mass movements but today the natural balance of soil is being upset far more frequently. Human impact alters nutrient content, leads to soil erosion, compaction and salinisation.
The problem was first recognized in the UK in the 1970's when water erosion of upland peat and wind erosion on large open fields was prevalent. A large quantity of soil was removed, much of which was the organic rich topsoil. The more topsoil that is removed the more erosion that occurs, as there are fewer roots to bind the soil.
- More intensive agriculture.
- Larger and more powerful agricultural machinery.
- Increase compaction of soil.
- Inappropriate cultivation of steeper slopes.
- Larger fields.
- Year round agriculture.
- Decrease in hedgerows.
- Population pressure.
Soil erosion leads to a decline in productivity, a reduction in organic content of soils, and more minerals and silt in rivers. Once topsoil is removed it is very difficult to replace.
Soils vary naturally in their fertility, and their ability to produce high or low crop yields depends on nutrient content, structure, drainage, local conditions of climate and relief, acidity and soil texture. Crop harvesting removes soil nutrients resulting in a poorer quality soil. Soil management aims to reduce soil erosion and nutrient losses in a variety of ways:
|Limitation of wind erosion.||Preserve moisture in the soil, plant windbreaks.|
|Control of slope run off.||Terrace slopes, apply humus, develop ditches that traverse hillslopes to intercept run-off, contour ploughing, limit field width.|
|Management of crops.||Cover crops, introduce crop rotation.|
|Limit gulley enlargement.||Plant trailing plants, construct dams.|
|Re-vegetate areas.||Limit grazing to allow re-growth, deliberate planting of vegetation.|