ISHS Acta Horticulturae 779: International Symposium on Growing Media
EXPERIENCE WITH SELECTED PHYSICAL METHODS TO CHARACTERIZE THE SUITABILITY OF GROWING MEDIA FOR PLANT GROWTH |
| Authors: | C. Blok, G. Wever |
| Keywords: | bulk density, total pore space, structural stability, root resistance, water retention, rewetting, hydrophobicity, water transport, oxygen transport |
| DOI: | 10.17660/ActaHortic.2008.779.29 |
| Abstract:
The variety of materials and mixes of materials used in horticulture as growing media is large. Peat products, wood products, composts, mineral fibres, mineral particles, synthetic foams, synthetic fibres and organic fibres; all these products are more or less suitable growing media. Selected physical aspects related to plant growth requirements, are used to discuss the suitability of growing media for plant growth. Aspects mentioned include bulk density, total pore volume, structural stability, root resistance, water retention, rewetting, hydrophobicity, water transport, and oxygen transport. Methods to measure these aspects and experience with the results are also discussed in this review. In conclusion, the physical properties used to assess the suitability of substrates for growth share a large dependence on pore architecture. This made it possible to relate the formulas for water retention, hydraulic conductivity and diffusivity to each other. It seems possible to extend this unification to resistance to rooting and rewetting. Bulk density, total pore space and structural stability exercise their influence on plant growth mainly through the key characteristics for growth assessment: resistance to rooting, water retention, rewetting and water and oxygen transport. Better definitions and possibly new methods to characterise rewetting, hydrophobicity and refreshment rate are advocated. When assessing the influence of water and oxygen transport, individual layers and gradients towards the roots are of importance because of the very fast transport rate changes with water or air filled pore space. | |
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