MEASUREMENT OF SOIL-WATER TENSION IN SINGLE AGGREGATES WITH USE OF THE FILTER-PAPER METHOD

The filter paper method was used to establish the retentivity curves of single aggregates. Aggregates (diameter 3-4 cm) from an Alfisol (sandy loam) and a Mollisol (sandy clay) were used. The aggregates had different water contents. Whatman No. 42 filter paper, attached to a conical plastic tube on the end of a rod, was inserted into a hole made in the aggregate. The hole was made using a small corer. The aggregates were sealed in wax, put into a plastic bag and stored in a thermo-constant room to equilibrate. After seven days the water content of the aggregates and of the filter papers were determined at 105-degrees-C. Retentivity curves for the aggregates are presented and sources of error are discussed.