Soil compaction
Of soil compaction is used when it high by applying load to deformation and thus to a change in the three-phase system floor comes.
With a relatively low load, a reversible (elastic) deformation occurs, which springs back to its original state after the load has ended. If there is a load above the point of the preload, a plastic deformation occurs , which is not reversible and therefore not completely springs back into the initial state. Thus, it is used mainly in the exceeding of the preload to shear the soil particles against each other and a Einregelung this with an increase in the solid phase with a simultaneous decrease of the liquid and gaseous phase. The compression can reach far in depth, it depends on the pressure distribution ( pressure bulb ) under the load.
Agriculture and Forestry
Soil compaction problems arise above all in agriculture , as well as in forestry , where particularly negative aspects appear. These soil compaction can be caused on the one hand by the use of very heavy machinery in unfavorable (moist) soil conditions. Decreases in air conductivity , water conductivity as well as increases in the previous load, the shear parameters , and storage density can be demonstrated.
On the other hand, the reasons for the increasing compaction of agriculturally used soils do not only lie in the load from the axle loads, in driving over them or in the wrong choice of tires. This is shown by the limited success that is achieved today with mechanical loosening or the use of wide tires. The soils compact again very quickly. In many cases, humus shrinkage and a greatly reduced soil life due to ever tighter crop rotation , lack of intercropping and lack of organic matter ( SOM (eg.) Manure or compost - shares) as well as the use of herbicides and insecticides , the reason for an increasing Compaction of the soil. The insecticides damage the edaphon and the herbicides reduce root penetration , both of which help improve the soil structure.
The problem of subsoil compaction below the plow sole on agricultural areas has proven to be particularly serious . In addition to the reduced water and air supply ( ascending as well as declining) for plants and microorganisms, increased penetration resistance for the plant roots also makes cultivation increasingly problematic.
Iron toxicity can also make itself felt. Iron is an essential trace element in plant organisms, where it influences photosynthesis and the formation of chlorophyll and carbohydrates . In soils it is present as Fe (OH) 3 at normal pH values . If the oxygen content of the soil is low, Fe (III) is reduced to Fe (II) through reduction. This brings the iron into a soluble form that is available to plants. If this availability increases too much under anaerobic conditions, for example due to soil compaction, damage to plants can occur due to iron toxicity, a phenomenon which is particularly known in rice-growing areas.
Although there are suitable measures to counteract this compaction, such as the use of terrarium tires , no-till or mechanical loosening measures, the regeneration of soil damage takes place very slowly, if at all, under natural conditions.
Soil compaction reduces or prevents the seepage of rainwater . As a result of soil compaction, heavy precipitation can lead to increased surface runoff and thus to soil erosion . The reduced storage capacity of the soil favors flood events ( flooding ). The entry of rainwater into the groundwater body is reduced, which creates the risk of a lowering of the groundwater level. Waterlogging can lead to a considerable loss of nitrogen in the soil, as the greenhouse gas nitrous oxide is increasingly formed in wet soils . The overall deterioration in growth conditions can ultimately also lead to an increase in fungal infestation and weed growth in crop plants , which can result in the increased use of chemical pesticides. In addition, the growth period of the plants can be shortened in wet and therefore relatively cool soils and the more difficult-to-work soils require more fuel to be used in agricultural machinery.
Soil compaction in lawns leads to holes in the sward, especially when cars are parked on the lawn. It is difficult to re-sow here; if solid ground and thus holes appear in lawns, only a thorough digging of the affected area will help . The method of spade diagnosis is particularly suitable for checking the causes of soil compaction .
Construction
While the soil compaction in agriculture and forestry generally regarded as undesirable, this is in construction often a necessity. Here, as compactors , for example, road rollers , vibratory plates , vibratory rammers used, etc., to obtain a stable base for construction or building and to enable a professional foundation .
Mining
When recultivating old opencast mines , the edge areas of the slopes sometimes have to be compacted in order to prevent settlement flow . This is the permanent slope protection for groundwater rose again and is especially in the Lausitz area spread.
As a rule, drilling equipment is used to drill a hole in the layers to be compacted and a defined charge of explosives is detonated. This causes a local change in the storage density.
See also
Literature (agriculture and forestry)
- A. Beste: Agricultural soil protection in practice. Basics, analysis, management. Preservation of soil functions for production, water protection and flood prevention. Berlin 2005, ISBN 3-89574-536-7 .
- A. Beste: How much water can my soil store in heavy rain? How much drought can my soil absorb? Improving soil functions and increasing soil fertility with the help of qualitative soil analysis. Guide for practitioners. incl. CD-Rom. Office for Soil Protection & Organic Agriculture, Mainz 2006, OCLC 635223794 .
- Günter Fellenberg: Chemistry of environmental pollution. 3. Edition. Verlag BG Teubner, Stuttgart 1997, ISBN 3-519-23510-2 .
- Handbook of Soil Science. ISBN 3-609-72210-X .
- Manual of soil protection. ISBN 3-609-65853-3 .
- Robert Bosch Stiftung (Ed.): Schwäbisch Haller Agrarkolloquium on soil use, soil functions and soil fertility. Memorandum for environmentally friendly land use in agriculture. Gerlingen 1994.
- Heavy load in the field. In: Spectrum of Science. 8, 2006, pp. 80-88.
Web links
Individual evidence
- ↑ Entry on iron. In: Römpp Online . Georg Thieme Verlag, accessed on June 16, 2014.
- ^ Günter Fellenberg: Chemistry of environmental pollution. 3. Edition. Verlag BG Teubner, Stuttgart 1997, p. 158.