5Kononova M M. Soil organic matter, its nature, its role in soil formation and in fertility (2nded) [ M]. London: Pergamum Press, 1964. 5-20.
6Christensen B T. Physical fractionation of soil and organic matter in primary particle size and density separates [ J]. Advance in Soil Science, 1992, 20: 82-90.
7Christensen B T, Physical fractionation of soil and structural and functional complexity in organic matter turnover [ J ]. European Joumal of Soil Science, 2001, 52:345-353.
