ISHS Acta Horticulturae 450: International Symposium Growing Media and Plant Nutrition in Horticulture
PHYSICAL PROPERTIES OF DIFFERENT POTTING MEDIA AND SUBSTRATE MIXTURES - ESPECIALLY AIR- AND WATER CAPACITY |
| Author: | U. Brückner |
| Keywords: | Potting media, white peat substrate, common substrates, substitutes, available water, unavailable water, air capacity |
| Abstract:
Container medium in horticulture serves primarily as mechanical support for the plant. It has only small reservoirs of water supply and short substrate columns affect drainage of water. Physical characterization of substrates is necessary to evaluate percentage of solid material, water- and air capacity. Physical measurements of substrates are done under standardized conditions will be changed during the growing period as a consequence of root growth, swelling and shrinkage and decomposition of organic material. In our experiments we evaluated the percentage of solid material, water and air in substrates at different suction levels from pF 0.4 (-2.5 cm) to pF 4.2=1.5 MPa using a pF equipment and a pycnometer. Water was distributed in light (pF 1–2), heavy (pF 2–4.2) and unavailable water. The physical properties of 14 common substrates mostly based on white peat substrate were examined. In order to improve the efficiency of substitutes (mineral sand, hortiperl, coconut coir, woodfibre, rice husks, paper substrate and styromull) 14 mixtures were also investigated. White peat substrates were considered to be optimal in light available water and air capacity. Compressing caused a dramatic decrease of air volume. Substrates contained compost, clay, wood chips and paper substrate without peat had only small water capacity. Determined values of different material mixtures with white peat substrate were almost close to that of the substrate, except in case of adding mineral sand. | |
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