Hunan Soil and Fertilizer Institute, Changsha, China.
J Basic Microbiol. 2020 Nov;60(11-12):1004-1013. doi: 10.1002/jobm.202000452. Epub 2020 Nov 1.
Carbon (C) is playing an important role in regulating soil nutrient cycling, maintaining soil fertility and crop yield, but there is still need to further study on how C source utilization characteristic respond to soil physical and chemical properties change with different fertilizer treatments under a double-cropping rice (Oryza sativa L.) field in southern China. Therefore, the effects of 34-year long-term fertilizer regime on C source utilization characteristic in rice rhizosphere and non-rhizosphere soils under a double-cropping rice field in southern China were studied by using O-H O method in the present paper. The field experiments were included four fertilizer treatments: mineral fertilizer alone (MF), rice straw and mineral fertilizer (RF), 30% organic manure and 70% mineral fertilizer (OM), and without fertilizer input as control (CK). The results showed that microbial biomass C content, basal respiration of soil microorganism and microbial growth rate in rice rhizosphere and non-rhizosphere soils with OM and RF treatments were significantly higher (p < .05) than that of CK treatment. The microbial C utilization efficiency (CUE) in rhizosphere soil with MF and CK treatments were significantly higher (p < .05) than that of OM treatment, but there was no significantly difference (p > .05) in microbial CUE in non-rhizosphere soil between MF, RF, OM, and CK treatments. In the different parts of soil, the microbial biomass C content and basal respiration of soil microorganism in rhizosphere soil were higher than that of non-rhizosphere soil, but the microbial growth rate and microbial CUE in non-rhizosphere soil were higher than that of rhizosphere soil. Compared with CK and MF treatments, the metabolic capacity of soil microorganism to exogenic C source with RF and OM treatments were significantly higher (p < .05) than that of MF and CK treatments. The largest type of exogenic C source used by soil microorganism was carboxylic acids, followed by amino acid and carbohydrate, and complex compounds was the smallest. In the different parts of soil, the metabolic capacity of soil microorganism to the types of exogenic C source in non-rhizosphere soil was higher than that of rhizosphere soil. The redundancy analysis results indicated that there had obvious difference in utilization characteristic of soil microorganism to exogenic C source among different fertilizer treatments. In conclusion, this results indicated that characteristic of soil C source utilization were significantly changed under different long-term fertilizer condition.
碳（C）在调节土壤养分循环、维持土壤肥力和作物产量方面发挥着重要作用，但在中国南方的双季稻田中，不同施肥处理下土壤物理化学性质如何影响 C 源利用特性，仍需要进一步研究。因此，本研究采用 13CO2 示踪法，研究了长期施肥（34 年）对中国南方双季稻田根际和非根际土壤 C 源利用特性的影响。田间试验包括 4 种施肥处理：单施化肥（MF）、稻秸与化肥（RF）、30%有机肥与 70%化肥（OM）和不施肥对照（CK）。结果表明，与 CK 处理相比，OM 和 RF 处理的根际和非根际土壤微生物生物量 C 含量、土壤微生物基础呼吸和微生物生长速率显著增加（p<0.05）。MF 和 CK 处理的根际土壤微生物 C 利用效率（CUE）显著高于 OM 处理（p<0.05），但 MF、RF、OM 和 CK 处理的非根际土壤微生物 CUE 无显著差异（p>0.05）。在不同土壤部位，根际土壤微生物生物量 C 含量和土壤微生物基础呼吸均高于非根际土壤，但非根际土壤微生物生长速率和 CUE 高于根际土壤。与 CK 和 MF 处理相比，RF 和 OM 处理的土壤微生物对外源 C 源的代谢能力显著高于 MF 和 CK 处理（p<0.05）。土壤微生物利用的外源 C 源主要类型为羧酸，其次为氨基酸和碳水化合物，复杂化合物最小。在不同土壤部位，非根际土壤微生物对外源 C 源类型的代谢能力均高于根际土壤。冗余分析结果表明，不同施肥处理下土壤微生物对外源 C 源的利用特性存在明显差异。综上所述，不同长期施肥条件下土壤微生物对 C 源的利用特性发生了显著变化。
