Extraction of soil organic matter under chemically mild conditions

Abstract
Large additions of urea greatly increased the effectiveness of some chemically mild extractants of soil organic matter. Brief agitation with an ultrasonic disintegrator also enhanced the action of these mixed solutions. With a range of soils, 0.05M Na4P2O7 in 8M urea extracted at least as much soil carbon as 0.05M Na4P2O7 in 0.5M NaOH. A solution of 0.3M NaHCO3 in 8M urea usually extracts less carbon but introduces only Na+ as a mineral contaminant.