ISHS Acta Horticulturae 644: International Symposium on Growing Media and Hydroponics
THE IMPORTANCE OF HYDRIC HISTORY ON THE PHYSICAL PROPERTIES AND WETTABILITY OF PEAT |
| Authors: | J.C. Michel, P. Morel, L.M. Rivière |
| Keywords: | peat, contact angle, water content, water ratio |
| Abstract:
The influence of desiccation/rehydration cycles on the wettability and physical properties of two peat substrates (weakly and highly decomposed peats) was studied. The analysis of their physical properties showed that the changes in water conditions deteriorate the physical properties of peats, with a decrease in total and pore volumes. However, the water content, expressed as the water ratio, remains virtually constant after several desiccation/rehydration cycles for the same water potential. In parallel, the wettability of peats was studied by contact angle measurements using a methodology based on the principle of capillary rise. Results obtained at different water potentials during a complete desiccation confirm that the wettability of peats depends on water content, and that these substrates acquire a hydrophobic character during desiccation. On the other hand, contact angles measured at -100 kPa during several desiccations are virtually similar, which indicate that the wettability of the materials is not affected by a series of desiccation and rehydration. These results can be correlated with water ratios. Indeed, even if the physical structures of peats change, the water ratio and consequently the wettability remain virtually constant for the same water potential during desiccation/rehydration cycles. The ability of peat to retain water, as expressed by the water ratio, seems to be a pertinent factor influencing peat wettability. | |
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