Quantity and quality of organic matter in forest and arable soils developed from sand and loess

Eight sandy and three loess forest and arable soils taken from the S-E region of Poland were used in the study. The following fractions of C were determined: total organic carbon, fraction soluble in 0.5 mol NaOH dm-3 (humic acids + fulvic acids), humic acids, fulvic acids, fraction soluble in 0.5 mol H2SO4 dm-3 (hemicelluloses) and residue. Quantity and quality of organic matter depended on horizon and soil use. The highest content was shown by fraction of humus acids and residue, whereas the lowest - hemicelluloses fraction. In most soils C ratio of humic to fulvic acids exceeded 1.0. On average, in humus horizons, it was higher in arable than in forest soils and in loess as against sandy soils. In sandy soils, a slightly higher content of humus fraction and lower residue one than in loess soils was found.