PHYSICAL PARAMETERS IN COMMERCIAL SUBSTRATES AND THEIR RELATIONSHIPS

Bulk density, total pore space, volume percent air, degree of shrinkage, water capacity, easily available water, buffering water and volume percent water at a suction of - 10 cm, - 50 cm, - 100 cm were measured.

The u. substrates presented less porosity, volume percent air and water capacity but more easily available water, buffering water and higher degree of shrinkage than the peats.

All the parameters measured were also compared with the optimum values for u. substrates and sphagnum acid peats.

A large part of the u. media presented good values for degree of shrinkage, water capacity and buffering water, while showed excessive porosity, high level of aeration and easily available water.

The peats often showed insufficient hydrological characteristics and low porosity compared to optimum values, however with bulk density and degree of shrinkage generally good.

All the physical parameters, except water capacity, presented high correlation, higher than in u. substrates.

The most interesting correlations were shown by degree of shrinkage, easily available water and buffering water. The first one correlated negatively with total pore space and volume percent air but positively with easily available water and buffering water. These last two correlated positively with water capacity but negatively with total porosity and volume percent air.

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