Capping

This article explains the term in soil science and agriculture; for the more general term in hydrotechnology see colmation , for wells and drainages see silting .

In soil science, silting is understood as the displacement of soil particles on the soil surface by raindrops or generally by (also flowing) water movement. Droplets ( hail , heavy rain , continuous rain , sprinkling ) mechanically break up the soil aggregates to a greater or lesser extent and remove fine particles or individual grains. The dissolved particles sediment in stagnant or easily flowing water ( surface runoff ), often in stratified form.

The consequences of silting up are on the soil surface:

• Leveling; this leads to accelerated surface runoff.
• Closure of soil pores; this leads to a reduction in water absorption ( infiltration ) and to a reduction in gas exchange between the soil and the atmosphere.
• Crust formation after drying; this hinders the breakthrough of germinating plants through the soil surface.

The extent of the silting depends primarily on the stability of the soil aggregates on the soil surface. The stability of the soil aggregates, in turn, is subject to change depending on the grain distribution of the soil, the previous soil cultivation, the period after cultivation and the soil moisture.

Freshly and intensively tilled (seedbed preparation), relatively dry, coarse silt and fine sand- rich arable soils are particularly sensitive to silting , which is therefore also highly prone to erosion on slopes. The risk and intensity of the silting are also dependent on the splashing effect of the raindrops, i.e. on the frequency of heavy rain events, the intensity and duration of rain, the size and height of the raindrops (several 100 m to 1000 m from clouds, 5 m to 100 m from tree tops , of grain <1 m). The most effective protection against silting up is therefore a plant or mulch cover in addition to mechanical loosening of the soil below the mulch cover through conservative tillage.

For agriculture - especially in arable farming , but also for wine and fruit cultivation - silting up of the arable land is both a disruptive factor in cultivation (difficulty with machine access) and in the growth of the planting material (poor water supply, damage to the soil fauna ) and counts as elemental damage . Therefore, it is generally covered by relevant agricultural insurance. The phenomenon rarely occurs on grassland and other covered ground.

literature

• Hartge, KH, Horn, R. (2009): The physical investigation of soils. 4th ed., E. Schweizerbart, Stuttgart.
• Roth, CH (1995): Physical causes of water erosion. In: Blume et al .: Handbuch der Bodenkunde , Wiley-VCH, Weinheim, Chapter 6.3.1.1, pp. 6-13
• Soil Analysis Handbook, 39th Supplement (March 2011), Section 9.3.3
• DIN 19683-16: 2009-01, “Soil quality - Physical laboratory tests - Part 16: Determination of the aggregate stability using the sieve immersion method” - Beuth, Berlin.

Web links

• Capping. (PDF; 24 kB) In: Erosion and Compaction. Canton Basel, accessed on January 1, 2009 (clear diagram of the cause). 

Individual evidence

1. ↑ Notes on silting up in connection with soil erosion and agricultural use , as well as other sites on Sachsen.de, accessed in July 2017