摘要:为揭示旱作区耕地土壤有机碳累积规律及其与土壤微生物群落间的相互作用机制，试验采用磷脂脂肪酸（PLFA）指纹图谱及土壤腐殖质形态分组的方法，通过田间定位试验，研究了马铃薯-马铃薯-油用向日葵-马铃薯-油用向日葵轮作模式下，有机、无机肥配施（不施肥、单施化肥、化肥配施牛粪、化肥配施羊粪、化肥配施生物有机肥、化肥配施黄腐酸钾）对土壤有机碳累积、土壤腐殖质形态的影响及其与土壤微生物群落结构间的相互关系。结果表明：在连续培肥5年间，随培肥时间延长，土壤有机碳呈波动性上升趋势。与对照相比，化肥配施牛粪、化肥配施羊粪处理土壤有机碳以年6.61%和8.97%的增长率累积增加，不同处理外源有机碳含量及有机肥种类的差异影响了土壤有机碳的累积速率。化肥配施高量有机肥（化肥+羊粪、化肥+牛粪）处理显著提高了土壤稳结态、松结态腐殖质含量及松结态/紧结态腐殖质的比例，且以PLFA表征的土壤细菌、真菌、放线菌、原生动物、土壤微生物群落总生物量与对照处理间均有显著性差异（P < 0.05）。与对照相比，各施肥处理的革兰氏阳性菌/革兰氏阴性菌（G+/G-）值均呈降低趋势；但不同有机无机相结合的土壤培肥方式对土壤G+/G-的比例没有显著差异。多元分析表明，基于土壤微生物主要类群磷脂脂肪酸含量的排序轴与基于土壤有机碳、腐殖质形态的排序轴之间相关性（P1=0.568，P2=0.611）较好，累积变量在98.69%上揭示不同有机无机培肥措施影响下的土壤微生物群落生物量与环境因子间的相互关系。土壤松结态腐殖质含量与土壤G+/G-比值正相关。外源有机碳的施入促进了土壤紧结态腐殖碳向稳结态、松结态腐殖质转化；较高量外源有机碳施入有助于提升土壤细菌、真菌的生物量。总体而言，土壤微生物群落结构的变化是受有机无机培肥措施所引起的土壤有机碳含量、腐殖质形态变化驱动；化肥配施牛粪和化肥配施羊粪有利于土壤有机碳积累和松结态腐殖质的形成，促进土壤中微生物生物量提高。研究结果可为宁夏中部干旱区土壤合理培肥提供科学依据。
关键词:有机无机培肥/
土壤有机碳/
微生物群落/
松结态腐殖质/
紧结态腐殖质/
磷脂脂肪酸
Abstract:The Phospholipid Fatty Acids (PLFAs) fingerprint and humus fraction methods were used to determine the accumulation of soil organic carbon in cultivated farmlands and the interaction mechanisms of soil microbial communities with soil organic carbon. The combined effects of organic manure and chemical fertilizer on soil organic carbon accumulation, soil humus forms and their relationships with soil microbial community structures were studied in a 5-crop rotation mode of 'potato-potato-oil sunflower-potato-oil sunflower' over a period of five years. The experimental treatments were as follows-no fertilization, inorganic fertilizer application, combined application of inorganic fertilizer and cow dung, combined application of inorganic fertilizer and sheep manure, combined application of inorganic fertilizer and biological organic fertilizer, and then combined application of inorganic fertilizer and fulvic acid potassium. The results showed that soil organic carbon fluctuated with increasing tendency over the five-year period. Compared with the control (no fertilization), soil organic carbon increased at annual average rates of 6.61% and 8.97% under the treatments of combined application chemical fertilizer with cow dung or separately with sheep manure. The rate of accumulation of soil organic carbon was influenced by the amount and type of added exogenous organic matter to the soil. The contents of stable or tightly combined humus and ratio of loosely combined humus to tightly combined humus increased following the addition of high quantities of organic manure (chemical fertilizer plus cow dung or chemical fertilizer plus sheep manure) and inorganic fertilizer. Compared with no fertilization, there were significant differences in soil bacteria, fungi, actinomycetes, protozoa and total microbial biomass, marked by phospholipid fatty acids under combined application of inorganic fertilizer and sheep manure or cow dung. The biomass ratio of gram-positive bacteria to gram-negative bacteria (G+/G-) in the treatments with inorganic fertilizer plus organic fertilizers decreased. There was no obviously difference in the ratio of G+/G- among treatments of combined application of inorganic fertilizer and organic fertilizers. Multivariate analysis showed a good correlation between the first ordination axes based on soil microbial biomass marked by PLFAs and the second ordination based on combined soil organic carbon and humus (P1=0.568, P2=0.611). The relationship between soil microbial biomass and soil environmental factors was explained by the 98.69% cumulative variation in spatial scale. There was a positive correlation between the content of loosely combined humus and G+/G- of soil microbial community. It was concluded that the tightly combined humus fraction gained higher stability than the loosely combined humus when exogenous organic carbon was applied to the soil. The soil bacteria and fungi biomass marked by PLFAs were promoted with increasing amounts of exogenous organic carbon in the soil. The biomass ratio of fungi to bacteria was not influenced by fertilizer management and amount of exogenous organic carbon. Generally, the change in soil microbial community structure was driven by the change in soil organic carbon content and soil humus fraction. Combined inorganic fertilizer with cow manure and inorganic fertilizer with sheep manure supported the accumulation of soil organic carbon and the formation of loose combined humus, but also promoted an increase in soil microbial biomass. The research provided a reliable scientific basis for soil fertilization in semiarid areas in Ningxia.
Key words:Combined application of inorganic fertilizer and organic fertilizer/
Soil organic carbon/
Microbial community/
Loosely combined humus/
Tightly combined humus/
Phospholipid fatty acid (PLFA)
? Equal contributors
注释:
1) ?同等贡献者:李倩, 主要研究方向为农作制度理论与技术, E-mail: 940380226@qq.com; 马琨, 主要研究方向为农业生态学, E-mail: makun0411@163.com
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