施肥对中国农田土壤微生物群落结构与酶活性影响的整合分析

Fertilization impacts on soil microbial communities and enzyme activities across China's croplands: a meta-analysis

【目的】施肥能直接或间接改变农田生态系统的养分平衡,从而影响土壤的物理、化学和生物学特性。本研究探讨不同种植制度和土壤条件下施肥对农田土壤生物学特性的影响程度,为合理施肥和土壤肥力提升提供科学依据。【方法】通过收集近10年(2008—2018年)来发表的文献,建立了包含185组微生物量及群落结构等相关内容的数据库。采用整合分析方法 (Meta-analysis),定量分析了施肥对土壤微生物量、群落结构以及酶活性的影响。【结果】与不施肥相比,施肥显著提高了土壤微生物磷脂脂肪酸(PLFA)和微生物量碳、氮含量,提高幅度分别为28.5%、30.9%和41.6%。施用(单施或配施)有机物料对土壤微生物总PLFA含量及微生物量碳、氮含量的提高幅度分别为47.3%、50.4%和58.7%,相当于施用化肥的2.8、2.4和3.9倍。与不施肥相比,施肥均能增加各类微生物菌群PLFA含量,对细菌、真菌及放线菌的提高幅度为23.8%～30.4%,对革兰氏阴性菌(G~–)和革兰氏阳性菌(G^+)的提高幅度为37.8%～43.2%,且施用有机物料处理对各类微生物菌群PLFA含量的提高幅度显著高于施化肥处理。施用化肥对土壤微生物总PLFA含量的提高幅度在一年两熟制区为17.9%,在水田和水旱轮作条件下为18.3%～27.6%,而在一年一熟制区及旱地条件下对土壤微生物总PLFA含量无显著影响。在不同pH的土壤中,施用有机物料对微生物总PLFA的提高幅度均显著高于施化肥处理。在pH <6与pH> 8的土壤上施用化肥对微生物总PLFA含量无明显影响。施肥显著提高了与土壤有机质分解相关的β-葡萄糖苷酶(42.4%)和乙酰氨基葡萄糖苷酶(174.5%)的活性,对与氮循环相关的亮氨酸氨基肽酶活性无显著影响。统计分析还表明,施肥并未改变土壤微生物的真菌细菌比(F∶B)和革兰氏阳性菌革兰氏阴性菌比(G^+∶G~–)。【结论】在不同种植制度、土地利用类型和土壤pH下,施肥显著改变了土壤微生物量和与有机质分解相关的酶活性,但未改变土壤微生物的真菌细菌比(F∶B)和革兰氏阳性菌革兰氏阴性菌比(G^+∶G~–)。单施或配施有机物料均有利于提高农田土壤微生物总量及各类菌群的生物量,效果显著好于单施化肥。

[ Objectives ] Fertilization directly or indirectly changes the balance of nutrients in agricultural ecosystems, thereby affecting soil physical, chemical and biological properties. It is necessary to explore the effects of fertilization on soil biological characteristics under different cropping systems and soil conditions, so as to devise optimal strategies for rational fertilization and soil fertility improvement. [ Methods ] By collecting data from published literature in the last 10 years （2008-2018）, a database containing 185 groups of microbial biomass and community structure was established. A meta-analysis was used to quantify the effects of fertilization on soil microbial biomass, community structure and enzyme activities. [ Results ] Compared with the unfertilized control, fertilizer application significantly increased the soil phospholipid fatty acids （PLFA） and microbial biomass carbon and nitrogen contents by 28.5%, 30.9% and 41.6%, respectively. Relative to the control, organic fertilizer application increased soil total PLFA and microbial biomass carbon and nitrogen contents by 47.3%, 50.4% and 58.7%, respectively, equivalent to 1.8, 1.4 and 2.9 times higher than those of the mineral fertilizer treatments correspondingly. Compared with the control, fertilization increased the PLFA contents of various microbial communities, with bacteria, fungi and actinomycetes increased by 23.8% to 30.4%, and Graxn- negative bacteria （G） and Gram-positive bacteria （G＋） increased by 37.8% to 43.2%. Organic fertilizer application significantly increased the PLFA contents of all types of bacteria relative to mineral fertilization. Mineral fertilization increased total PLFA contents by 17.9% in double-cropping system, and 18.3%-27.6% in paddy or upland-paddy. However, mineral fertilization had little effect on soil microbial biomass under mono-cropping or upland. The magnitude of increased soil microbial total PLFA contents was significantly higher in soils subjected to organic fertilizer application as compared to mineral fertilization in soils with various pH. The application of mineral fertilization in soils with pH 〈 6 and pH 〉 8 had no effect on soil microbial total PLFA contents. Compared with the control, fertilization significantly increased the activities of 13-glucosidase （42.4%） and N- acetyl-glucosaminidase （174.5%） involved in soil organic matter decomposition, but did not for the activity of leucine axninopeptidase related to nitrogen cycle. Statistical analysis also showed that different fertilization did not change the fungi/bacteria （F ： B） and the Gram-positive bacteria/Gram-negative bacteria（G＋ ： G） of the soil microorganisms. [ Conclusions ] Fertilization changed soil microbial biomass and enzyme activities associated with decomposition of organic matter under different cropping systems, land-use types and soil pH gradients, but did not change the fungi/bacteria （F ： B） and the Gram-positive bacteria/Graxn-negative bacteria （G＋ ： G-） of the soil microorganisms. Organic material application （alone or combined with mineral fertilizers） is conducive to improving soil microbial activity and diversity in farmland, the effect is significantly better than that of single application of mineral fertilizer.