施用玉米秸秆和接种蚯蚓后几种土壤活性有机碳的动态变化

通过室内培养试验,研究在施用玉米秸秆和接种蚯蚓后,土壤微生物生物量碳(SMBC),水提取碳(WEOC),碳水化合物(CHOC)和酚类物质(PEOC)等活性有机碳组分的动态变化。研究结果表明,在不施秸秆或表施秸秆的情况下,接种蚯蚓对四种活性有机碳组分含量都有一定的促进作用,且在表施秸秆的情况下达到显著水平,其SMBC、WEOC、CHOC和PEOC的含量与不接种蚯蚓相比,分别增加了33.50%、43.13%、68.21%和30.28%。接种蚯蚓在混施秸秆的处理中只有WEOC的含量增加,而SMBC和CHOC含量分别降低了11.04%和16.63%,PEOC的变化不明显。不论接种蚯蚓与否,秸秆的施用对4种组分都有显著的促进作用,其中秸秆混施处理的作用最显著。接种蚯蚓和秸秆施用都能提高土壤WEOC的质量(CHOC/PEOC的比值)。方差分析表明,蚯蚓、秸秆和时间对活性碳组分含量都有显著影响,并且因子间存在强烈的交互作用。土壤活性有机碳各组分除SMBC以外,WEOC、CHOC和PEOC的含量变化受秸秆因子的影响最大,方差解释比例v分别达到82.35%、62.53%和75.82%。试验结果也表现出较一致的随时间的波动性。相关性分析表明,所测定项目SMBC、WEOC、CHOC和PEOC之间有显著的相关性。

Effects of earthworm and maize stalk application on the dynamic variation of soil active organic carbon

The active organic carbon in soils include microbial biomass carbon, water dissolved organic carbon, mineralizable carbon and so on. Earthworms, as one of important soil macro animals, and crop residues have great role in modifying the composition of soil active carbon. However, few studies were carried out in this area. Our ten weeks experiment in the lab was focus on the dynamic changes of biologically active organic fractions of soil such as microbial Biomass carbon (SMBC), water extractable organic carbon (WEOC) Carbohydrate (CHOC) and dissolved phenols (PEOC), which were affected by maize residues and earthworms (Metaphire guillelmi). Soil samples (orthic aquisols) were collected from Rugao County, Jiangsu Province. Treatments were: 1. no earthworms inoculation, no residues application (S); 2. earthworms inoculation only (SE); 3.suface application of redidues only (SRC); 4. surface residues + earthworms inoculation (SRCE); 5. residues buried and mixed with soil only (SRM); 6. residues buried and mixed with soil + earthworms inoculation (SRCM). Result indicated that the inoculation of earthworms increased the content of SMBC, WEOC, CHOC and PEOC, and the differences among the treatments were significant when surface residues covered the ground. But the content of SMBC and CHOC decreased by 11.04% and 16.63% respectively, in the treatment of residues buried and mixed with soils. The possible reason may due to the ingestion of microbe and organic matter by earthworms. Both treatments of surface and buried application of residues had significant effects on all types of active carbon contents determined. Whether earthworm inoculation or not, comparing the effects of the residue application, the buried and mixed residues with soil had stronger effects on content of all composition of active organic carbon. Results of a three-way ANOVA showed the effects of earthworm inoculation, residues application and sampling time all had strong significant effects on results. The v of residues on content of WEOC, CHOC and PEOC were 82.35%, 62.53% and 75.82% respectively. The results also had a uniform changing trend as the inoculation time. There were significant correlation with each other among WEOC, SMBC, CHOC and PEOC.