ISHS Acta Horticulturae 408: International Seminar on Soilless Culture Technology Protected Crops Mild Winter Climates
GRANULOMETRIC ALTERATION, AIR-ENTRY POTENTIAL AND HYDRAULIC CONDUCTIVITY IN PERLITES USED IN SOILLESS CULTURES |
| Authors: | R. Orozco, O. Marfà |
| Keywords: | Perlite, soilless cultures, granulometry, air-entry potential, hydraulic conductivity, substrates |
| Abstract:
Expanded perlite with different granulometric compositions is becoming more widespread for use as a substrate in soilless grow-bag cultures in protected coastal farming in Southeast Spain. Compared to other inert substrates such as rockwool, there is much less information available on perlite both in terms of its physical properties and its behaviour in cultures. Our purpose here is to provide a statistical study of granulometric alteration due to use on different types of perlite, the air-entry potential of the substrate and water distribution under container capacity conditions and the hydraulic conductivity of the substrate. The results show the usefulness of statistical parameters when applied to the interpretation of granulometric alterations; that significant values for air-entry potential for fine and intermediate grades limit substrate air-filled porosity. The results also show the relationship between unsaturated hydraulic conductivity (Kunsat) and the bioproductive response of lettuce cultivated in different types of perlite. Comments are included on the possible significance of Kunsat in substrate-plant water relations and in irrigation management. | |
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