Earthworm Effects Soil Biological Properties, Active Organic Carbon And Stabilization Of Soil Aggregates

Earthworms are one of the most important members of soil fauna in temperate ecosystems. They are involved in the regulation of organic matter decomposition, nutrient cycling processes and modification of soil structure stability by ingesting and mixing the inorganic material with organic matter.This short-term microcosm experiment was used to determine the influences of earthworm activity on soil biological properties, soil organic carbon and soil structure with agricultural residues maize litter. Six treatments with four replicates were selected, i.e. no corn residues and no earthworms (S); no corn residues with earthworms innoculated (SE); with residues covered and no earthworms (SRC); with residues covered and with earthworms innoculated (SRCE); with residues mixed and no earthworms (SRM); with residues mixed and earthworms innoculated (SRME).The objectives of this dissertation were to classify the influences of earthworms on: 1) soil biological properties by analyzing soil microbial community composition, soil microbial biomass and glucose induced respiration (SIR); 2) soil organic carbon contents by analyzing water- extractable total organic carbon (WEOC), carbohydrate carbon (CHOC) and phenolic carbon (PEOC) ; 3) soil aggregate stability by dry and wet sieving methods. Main results were as follows:1) The three-way ANOVA analysis, of which earthworm, maize litter and sampling time were sources of variances, indicated that earthworm accounted for the variations in the CFUs of bacteria, yeast and SIR 18.7%, 13.3% and 17.2% respectively. Maize litter accounted for the most of total variation in soil microbial biomass nitrogen (SMBN, 96.5%) and the CFUs of soil microbial (77.9%: bacteria; 69.4%: yeast; 85.3%: Filaceous fungi). Earthworms increased the CFUs of yeast, bacterial and SIR obviously. The most obivious was in the treatments such as SE (5.2 times), SRCE (8.9 times) and SRME (2.5 times) as compared with the corresponding treatments without earthworms' innoculated. Effects of earthworms on the CFUs of filaceous fungi were influenced by the way the maize litter...