SATURATION RATE AND HYSTERESIS OF SUBSTRATES

In substrates effective transport of water is important to provide the root with water and nutrients.
Insufficient transport of water leads to dry areas and therefore a limited use of the growing medium.
The unsaturated hydraulic conductivity and hysteresis are the main factors in the saturation process.
These factors are especially important if irrigation is done from the bottom, as in flooded bench techniques, or locally, as in trickle irrigation.
Because there is only minor knowledge about these factors, research was performed with different media.
The rate of water absorption at different moisture levels and the water retention curve, both the drying and wetting curve, were determined.
The effect of clay, sand and perlite in mixtures with peat was tested.

There were large differences in water absorption rate between peat substrates.
For dry materials the differences could be more than a factor 100. The absorption rate of peat was increased by adding clay, sand or perlite, the extent of the increase depending on the amount and the type of addition.
In this research granulated clay was most effective.
If peat was wet, the effect of an addition of the mentioned products on saturation rate was minor.
The different media had substantial differences in hysteresis.
Clay, sand and coir dust had minor hysteresis, perlite moderate while for peat it varied.
Coarse peat had the highest hysteresis.
If peat was mixed with clay, sand or perlite the hysteresis did not significantly change.

International Symposium Growing Media and Plant Nutrition in Horticulture

G. Wever, A.A. van Leeuwen, M.C. van der Meer

physical characterization, water transport, sand, clay, perlite, peat

https://doi.org/10.17660/ActaHortic.1997.450.34