Articles
STABILITY OF GROWING MEDIA FROM A PHYSICAL, CHEMICAL AND BIOLOGICAL PERSPECTIVE
Article number
819_12
Pages
135 – 142
Language
English
Abstract
Horticultural crops have specific demands on the structure of growing media due to the small rooting volume.
Water uptake, buffering and availability as well as oxygen diffusion must be optimal.
Also pH and concentration of nutrients and other salts should be meeting the plants demands.
Biological activity should be of such kind that it does not compete with the plant.
A stable growing medium is essential for successful growing of a range of species.
Stability can be defined from different perspectives; physical, chemical and biological.
Physical stability of growing media means that the structure is stable, and water holding capacity, moisture retention, aeration, etc. is not changing much.
Chemical stability includes buffering of pH, buffering of cations and anions in terms of respectively cation exchange capacity (CEC) and anion exchange capacity (AEC). These can be influenced by degradation or decomposition of the substrate.
Biological stability concerns mainly breakdown of organic matter.
Whenever organic material is prone to breakdown this can cause nitrogen immobilisation, loss of physical structure and change of chemical behaviour.
Considerable research has been carried out to study stability of growing media.
Most research however has been of an empirical nature and gives no real tools to describe stability.
Methods of analysis have been mainly developed to describe biological activity.
For growing media constituents, methods describing the oxygen uptake rate (OUR) have been shown to be of use in quantifying bio-activity.
Water uptake, buffering and availability as well as oxygen diffusion must be optimal.
Also pH and concentration of nutrients and other salts should be meeting the plants demands.
Biological activity should be of such kind that it does not compete with the plant.
A stable growing medium is essential for successful growing of a range of species.
Stability can be defined from different perspectives; physical, chemical and biological.
Physical stability of growing media means that the structure is stable, and water holding capacity, moisture retention, aeration, etc. is not changing much.
Chemical stability includes buffering of pH, buffering of cations and anions in terms of respectively cation exchange capacity (CEC) and anion exchange capacity (AEC). These can be influenced by degradation or decomposition of the substrate.
Biological stability concerns mainly breakdown of organic matter.
Whenever organic material is prone to breakdown this can cause nitrogen immobilisation, loss of physical structure and change of chemical behaviour.
Considerable research has been carried out to study stability of growing media.
Most research however has been of an empirical nature and gives no real tools to describe stability.
Methods of analysis have been mainly developed to describe biological activity.
For growing media constituents, methods describing the oxygen uptake rate (OUR) have been shown to be of use in quantifying bio-activity.
Publication
Authors
J.B.G.M. Verhagen
Keywords
growing media, stability, break-down, physical properties, nitrogen immobilisation, oxygen uptake ratio (OUR)
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