METHOD FOR MEASURING AIR SPACE AND MOISTURE CONTENT AT DIFFERENT POT DEPTHS

A method has been developed to characterize the air and moisture distribution at different depths in pots using a PVC cylinder of dimensions 20 cm (height) and 15 cm (inner diameter). The lower part (height 8 cm; 12–20 cm from the top) comprises a solid base above which, at 2 cm, is a secondary base perforated with holes to allow for passage of water which can be removed via a hose connection.
This secondary base is covered with a filter of sintered polyethylene plastic particles.
The upper part consists of six consecutive detachable rings (each of height 2 cm). The substrate in the cylinder can be saturated and drained (to a depth 12 cm) by means of an adjustable water table connected to the base of the cylinder via a hose.
During the first saturating and draining cycle, an extension collar (height 8 cm) is placed on the cylinder, but during the second similar cycle no collar is used.
Bulk density, porosity, air space and moisture content are determined in each ring layer.
The results show that the air space decreases with an increase in pot depth and the degree of decomposition of the peat.

The cylinder is now being used with TDR (Time Domain Reflectometry) probes and minitensiometers as to measure moisture content and pressure head respectively.

International Symposium on Growing Media & Plant Nutrition in Horticulture

G. Kritz, T. Khaled

substrate, Sphagnum peat, decomposition degree, bulk density, porosity

https://doi.org/10.17660/ActaHortic.1995.401.12