9Kaiser M, Ellerbrock R H. Functional characterization of soil organic matter fractions different in solubility originating from a long-term field experiment[J].Geoderrna,2005,127(2-4): 196-206.
10Rantaray S K, Ghosh B C, Mittra B N. Effect of fly ash, organic wastes and chemical fertilizers on yield, nutrient uptake, heavy metal content and residual fertility in a rice-mustard cropping sequence under acid lateritic soils[J]. Bioresource Technology,2003,90(3):275-283.