不同施肥制度对石灰性紫色水稻土中氨氧化古菌群落结构的影响

研究不同施肥制度对水稻土氨氧化古菌(AOA)群落结构和垂直分布特征的影响,可以深入认识不同施肥制度下的石灰性紫色水稻土氮素循环特征及微生物驱动机制,为该地区科学施肥、培肥地力提供理论依据。利用化学分析和变性梯度凝胶电泳(DGGE)对不同施肥制度下石灰性紫色水稻土理化性质和AOA群落结构进行了分析。结果显示:相对于无肥处理,施肥会降低石灰性紫色水稻土pH和硝氮含量,而增加土壤有机质、全氮和氨氮含量。伴随土壤深度增加,土壤pH增加,全氮和硝氮含量降低,氨氮含量变化趋势不明显。不同施肥制度在不同土壤深度对石灰性紫色水稻土AOA群落结构产生不同的胁迫效应,不同施肥制度下的AOA群落结构在0—20 cm处差异不明显;土壤深度增加,不同施肥制度下的AOA群落结构表现出明显差异,CK和N肥处理下的AOA群落结构较简单。AOA群落结构多样性指数和丰富度随土壤深度增加而减小。石灰性紫色水稻土AOA与来自不同土壤和水体环境的AOA具有明显相似性。冗余梯度分析(RDA)显示pH(P=0.012)是造成石灰性紫色水稻土AOA群落结构差异的主要原因。研究揭示石灰性紫色水稻土中的AOA群落结构受施肥制度明显影响并表现出明显的垂直分布特征。

Impact of different long-term fertilization systems on ammonia oxidation Archaea community structures in Calcareous Purple Paddy soil

Increasing evidence revealed that ammonia oxidation Archaea (AOA) belonging to Thaumarchaeota could control nitrification in various agricultural ecosystems. Studying the impact of different long-term fertilization systems on the shift of the AOA community structure and vertical distribution would contribute to understanding the soil nutrient biogeochemical cycles and microbial drive mechanisms. In the present study, an "N, P, K long-term fertilization field experiment (1982-2014)" was established in a Calcareous Purple Paddy soil in Suining City, Sichuan Province of the PR China. Eight treatments including three chemical fertilizer (CF) treatments (N, NP, and NPK), three CF plus farmyard manure (M) treatments (NM, NPM, and NPKM), M only, and no fertilizer (CK) as control were used. Soil samples amended with different long-term fertilization systems at four different depths (0-20, 20-40, 40-60, 60-90 cm) were collected; the soil physico-chemical parameters and the shift of the AOA community structure and vertical distribution were analyzed by chemical analysis and denaturing gradient gel electrophoresis (DGGE). The results showed that compared to the no fertilizer treatment (CK), soil pH decreased under the CF treatments, and showed little variation under CFM treatments. The pH values in the 0-20 cm soil depth were lower than those in other soil depths. The combined use of farmyard manure and chemical fertilizer could also improve the soil total nitrogen concentration. The total nitrogen content in 0-20 cm soil depth was also higher than that of other depths. Fertilizer increased the soil ammonia content in the 0-20 cm soil depth, and in this soil depth, the CK treatment had the lowest ammonia concentration. Furthermore, soil ammonia concentrations under the four CFM fertilizer treatments (e.g. M, NM, NPM, and NPKM) were similar. Additionally, chemical fertilizer plus farmyard manure decreased the soil nitrate concentration, and the nitrate concentration in the 0-20 cm soil depth was higher than that of other depths. Based on the DGGE analysis, different fertilization systems affected the AOA community structure in different soil depths differently. The AOA community structure in the 0-20 cm depth with different fertilizer amendments showed minor variation. With increasing soil depth, the AOA community structure with different fertilization systems varied significantly. The AOA community structure in the CK and N fertilized soil were much simpler than those under CF and CFM fertilizer treatments. However, the AOA community structure showed significant vertical variation, both the richness and Shannon-Wiener diversity index in the 0-20 cm soil depth were the highest, while those in the 60-90 cm soil depth were the lowest. According to the sequence and phylogeny analysis, AOA in Calcareous Purple Paddy soil were all affiliated to Thaumarchaeota, and they were highly similar to the AOA in different soil and water environments. According to the redundancy gradient analysis (RDA), four soil physico-chemical parameters such as pH, total nitrogen, ammonia, and nitrate concentration showed 11.3, 2.8, 1.8, and 1% contributions to the AOA community structure, respectively. Soil pH (P=0.012) was the critical factor to shape the AOA community structure in Calcareous Purple Paddy soil. The study revealed that AOA in the Calcareous Purple Paddy soil responded to the fertilization systems variously, and showed an obvious vertical distribution.