Particle-size distribution

Soil texture

Important parameter for the characterisation of soils

Based on the particle-size distribution a soil can be assigned to a distinct soil texture. This procedure considers only the fine soil which comprises all particles with an equivalent diameter smaller than 2 mm (= 2000 µm). Soil constituents bigger than 2 mm are referred to as soil skeleton or coarse soil. The fine soil is composed of different particle-size fractions, i.e., sand (S), silt (U) and clay (T) which - according to the German particle-size classification - include the following particle sizes:

Under natural conditions these particle-size fractions mostly occur as mixtures and only rarely in their pure form. The ratio of the size fractions to one another determines the soil texture and the properties of the soil. The mixtures can be described by frequency distributions and summation diagrams.

The predominant particle-size fraction is name-giving, e.g. loamy-sand means a sandy soil containing a smaller loam fraction. The term 'loam' refers to a soil containing more or less equal fractions of sand, silt and clay.

As one of the most conservative soil features the particle-size distribution is an especially useful and meaningful parameter.

The particle-size distribution is also determined in suspended particulate matter (SPM) and in sediments.


Sand Particle-size fraction with an equivalent diameter of 2000 - 63 µm
Silt Particle-size fraction with an equivalent diameter of 63 - 2 µm
Clay Particle-size fraction with an equivalent diameter < 2 µm


Suspended particulate matter Fine insoluble mineral or organic particles in the water phase
Soil Soil is livelihood and biosphere for humans, animals, plants and soil organisms. All the substances brought in are transported, transformed and/or accumulated in the soil.

Sampling area

BR/NP Berchtesgaden The only high mountains national park in Germany and an area of the Limestone Alps with international relevance
Saarländischer Verdichtungsraum Important, old-industrialised conurbation in Germany.
Bornhöveder Seengebiet Main water divide between the North- and Baltic Sea
Rhein Longest river in Germany
NP Bayerischer Wald Germany's first national park
Elbe Fourth largest river basin in Central Europe
Verdichtungsraum Halle-Leipzig Region in the chemical triangle of Central Germany
NP Harz Germany's largest forest national park
Solling Second highest and largest low mountain range in Northern Germany
BR Pfälzerwald Germany's largest connected forest area in a range of low mountains
Oberbayerisches Tertiärhügelland The Upper Bavarian Tertiary Uplands are a part of the Southern German Molasse Basin
Donau Second largest river in Europe

Sampling period

2002 - 2015