Bulk Density as an Indicator of Pore Space in Soils Usable By Nematodes

Abstract

In studies of nematode populations, designation of the soil type in which they occur does not define the space available or other soil characteristics adequately. Bulk density is a readily determined soil parameter, but theoretical considerations suggest that, taken alone, bulk density is of little value as an indicator of the space in soil inhabitable by nematodes. Except in coarse mono-particulate sands, the same is true of total porosity. Results from measurements made on 'undisturbed' samples of mineral topsoils tend to confirm the theoretical deductions but estimates of bulk density, particle size class and land use together improve the prediction of usable pore space. Little is known of the ability of nematodes to traverse large air-filled pore spaces but nematode length may be an important factor. Better methods of measuring the size distribution of pores are needed and more investigation to identify the critical soil physical parameters relevant to nematodes.