Short-term effects of different tillage modes combined with straw-returning on the soil labile organic carbon components in a farmland with rice-wheat double cropping. Soil Particle Composition and Its Relationship with Nutrient Contents in a Quercus aquifolioides Forest at Different Altitudinal Gradient Study on the Active Organic Carbon in Soil under Different Types of Vegetation Effects of different straw-returning regimes on soil organic carbon and carbon pool management index in Guanzhong Plain, Northwest China EFFECT OF INTENSIVE CULTIVATION ON THE CARBON POOL OF SOIL IN PHYLLOSTACHYS PRAECOX STANDS Effects of simulated acid rain on soil microbial biomass carbon and total organic carbon in a monsoon evergreen broadleaved forest at the Dinghushan Nature Reserve