Substrate (soil)

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Substrate in connection with soil is the respective basic material for various natural processes and technical applications, is mostly in the form of granular matter and often consists of crushed rock.

In the geosciences , the substrate (Latin underlay ) describes the raw material for soil formation , for example the raw rock at the site.

In horticulture , the term substrate refers to all kinds of nutrient media, including the grown soil, which is characterized by its respective soil type .

At the same time, the soil is also a substrate (ecology) in the sense of a material on and in which organisms live. It contains the respective substrate (Biochemistry) in the sense of various biomolecules and microorganisms to be reacted chemical compound .

Substrates in horticulture

These are made from different soils, by adding aggregates , from soil mixtures or as soil-free substrates up to the use of liquid nutrient solutions.

In the open-air cultivation of tree nursery plants, in fruit cultivation and field vegetable cultivation, the plants are mainly cultivated in natural soils; In the greenhouse, the plants usually grow in substrates that are more or less separated from the ground. This is a consequence of the intensive use under glass (optimal growth conditions are economically necessary) - in connection with the arid climatic conditions (salt accumulation in the topsoil) - and the need for closed cultivation methods to protect groundwater .

Classification of soils (substrates)

Mixtures are usually used for substrates containing earth. As a main ground those earth are referred to, which form the major portion of the substrate; Together with auxiliary soils or additives, industrial soils are produced from them.

A division according to the humus content into mineral soils based on clay and sand as well as humus soils or humus mineral earths ( composts ) is also common. Soils with a low pH value are produced by peat peat : wet peat from peat soils and dry peat from leaf soils and coniferous soils.

Sand and peat can reduce the nutrient content of the substrate. Sand, for example, gives potted plants better stability and supports drainage in the substrate. Peat is used because of its excellent water storage capacity and for better ventilation when the soil is very moist . The clay content in the substrate is used to provide buffer capacity for nutrient salts ; this is required, for example, when cultivating roses.

Heavy substrates have a high proportion of clay, light soils mainly contain sand and peat.

Standardized growing media

Mineral fertilization (mg / l)
Raw materials lime N P 2 O 5 K 2 O
Peat growing medium
TKS 1 for sowing and pricking out 100% white peat 6 kg of carbonate of lime
pH 5.0–6.0
140 120 220
TKS 2 for potting 100% white peat 6 kg of carbonate of lime
pH 5.0–6.0
430 240 530
Potgrond for earth pots 60–70% black peat, 30–40% white peat, 40–70 l / m 3 sand 7 kg dolomite lime / m 3
pH 5.5-6.0
160-220 190-270 220-310
Standard earth according to Fruhstorfer
Type 0 for your own fertilization 20–40% clay + 60–80% white peat (possibly up to 50% black peat) pH 5.5–6.5 also uncalcified <50 <30 <60
Type P for sowing and pricking out pH 5.5-6.5 150-200 100-200 100-300
Type T for potting pH 5.5-6.5 250-400 200-400 200-500
Bark culture substrate
RKS 0 30–60% bark humus + white peat, black peat, clay 2–4 kg carbonate of lime / m 3
pH 5.5–7.0
30-100 <200 <200
RKS 1 100-250 150-300 200-500
RKS 2 250-450 200-400 300-600

Industrially produced soils, substrates, aggregates

Unit earth and Torfkultursubstrate used in horticulture as industrially manufactured earth. They are standardized, free from pests and diseases and, in comparison to self-made company soils, are often lighter (transport advantage). Examples are standard soil P for sowing and cuttings, standard soil ED73 with slow release fertilizer for heavy consumers ; Peat culture substrates TKS with raised bog according to DIN 11542, enriched with main nutrients and trace nutrients.

  • Expanded clay , also Lekaton , is used as a strengthening aggregate with low density in soil or as a soil-free substrate for hydroponics ;
  • Perlite , vermiculite, expanded shale are used as low-density mineral aggregates for better air flow, for example in soil for cuttings, sowing and pricking soil;
  • Plastics such as Styromull (made of polystyrene , water-repellent) or Hygromull , polyurethane foam , with a high water absorption capacity are added as synthetic additives;
  • In recent years, soil additives have been increasingly developed that are highly porous and mineral and serve as water storage or soil optimizers, especially in semi-arid and arid areas. Additions with superabsorbent polymers (hydrogel polymer) are also common. These composite materials, which store water and nutrients, are also suitable as additives for planting and growing media.
  • Other organic additives are mostly waste from other productions, such as grass hulls, wood fibers, coconut fibers or bark.
  • Stone wool made from heated dolomite is used as a soil-free substrate in vegetable and ornamental plants;
  • Seed gel : A nutrient gel developed by NASA for growing plants.

See also


  • Bernhard Berg: Basic knowledge of the gardener . Ulmer, Stuttgart 1976, ISBN 3-8001-1120-9 , pp. 198-206 .
  1. Heinz Jansen: Horticultural plant production: Basics of cultivation under glass and plastics . Ulmer, Stuttgart 1998, ISBN 978-3-8252-1278-0 , p. 320.

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