Compression of agricultural soils from Quebec

Static uniaxial compression tests were performed on 26 agricultural soils from Quebec. Compression lines (bulk density vs. applied load) were obtained at different water contents for each soil previously sieved to 6 mm. For soils with clay contents less than 35%, the compression index (slope of the compression line) was best correlated with the mineral fraction of the soil (r = 0.75^** with clay and r =−0.78^** with sand). For clay-rich soils, the compression index was best correlated with organic carbon content (r = −0.75^**). The bulk density under standard compression conditions (100 kPa load and 50% water saturation) was related to both clay (r = −0.80^**) and organic carbon (r = −0.77^**). This parameter was also highly correlated with the soil lower plastic limit (r = −0.95^**) which corroborates the observation that the consistency limits can be good predictors of other mechanical properties which are more difficult to determine. Results suggested that both the mineral and the organic fractions have much influence on the compressive behaviour of Quebec agricultural soils.