Effects of organic and conventional management on physical properties of soil aggregates

The aim of this study was to compare the effect of organic and conventional management systems on total porosity, water and ethanol sorptivity, repellency index, and tensile strength of soil aggregates. Two size fractions of soil aggregates (15-20 and 30-35 mm) were collected from the 0-10 and 10-20 cm depths. Data on water and ethanol sorptivities of the initially air-dry soil aggregate fractions were obtained from the steady state flow measurements using an infiltration device. Water repellency was identified by the ethanol/water sorptivity method. The total porosity was higher in aggregates from the conventionally than organically managed soil irrespective of soil layer or aggregate size. Infiltration and sorptivity of ethanol (60 mm(3)) were faster under the conventional than organic management irrespective of aggregate size and depth. Infiltration and sorptivity of water in 30-35mm aggregates were greater under organic than conventional management. The repellency index was mostly higher for the conventional management of soil and for agregates 30-35 than 15-20 mm in each management system. Aggregate crushing strength was in most cases greater under the organic than conventional management and could increase resistance to compaction and carbon sequestration under the former.