有机和无机肥配比对黄褐土硝化和反硝化微生物丰度及功能的影响

Effects of combination of organic and inorganic fertilizers on abundances of nitrifiers and denitrifiers and their function in yellow-cinnamon soil

【目的】土壤硝化与反硝化作用是氮循环的两个关键环节,本文研究不同比例的有机、无机肥配施对硝化和反硝化进程产生的影响,为高效施肥提供理论基础。【方法】在安徽农业大学农翠园试验基地的黄褐土上进行了小麦–玉米轮作田间试验。试验以不施氮肥为对照(CK),在小麦、玉米总施氮量相同的条件下,设置5个处理,分别为单施无机肥(T1)、无机肥∶有机肥=2∶1(T2)、无机肥∶有机肥=1∶1(T3)、无机肥∶有机肥=1∶2(T4)、单施有机肥(T5)。在小麦拔节期,取0—20 cm土壤样品,利用荧光定量PCR技术测定反硝化和氨氧化微生物丰度,并结合反硝化能力、N_2O/(N_2O+N_2)产物比、土壤呼吸、硝化势和氨氧化细菌(AOB)与古菌(AOA)对硝化势相对贡献率的测定,分析江淮地区长期有机和无机肥配施对黄褐土硝化、反硝化微生物丰度及其功能的影响。【结果】单施无机肥或有机肥处理的硝化势均高于不同配比处理。与添加有机肥相比,增施无机肥会显著增加AOA的丰度和硝化贡献率。在反硝化方面,反硝化能力和土壤呼吸随着有机肥投入量的增加而增加,单施有机肥处理显著高于其它处理。nir S和nos Z型反硝化菌丰度随着有机肥的增加而增加,而nir K型反硝化菌丰度呈减少趋势。相关分析表明,反硝化能力与nir S型、nos Z型反硝化菌丰度、有机质和可溶性有机碳含量极显著正相关,与nir K相关性不强。【结论】与单施无机肥或有机肥处理相比,有机和无机肥适当配施可降低土壤硝化势,并能调控AOA和AOB在硝化过程中的作用,有效地降低土壤反硝化损失。

【Objectives】Soil nitrification and denitrification are two key pathways in nitrogen cycling. The paper studied the effects of combined application of organic and inorganic fertilizers on nitrification or denitrification, aiming to provide theoretical base for the scientific nutrient managements in maize and wheat rotation system.【Methods】A field experiment was conducted in the yellow-cinnamon soil, located in the Cuiyuan Experimental Base of Anhui Agricultural University. Using no nitrogen fertilizer as control and at the same total N input levels in winter wheat and maize system, five combination ratios of inorganic and organic fertilizers were setup： only inorganic fertilizer（T1）, ratios of inorganic fertilizer to organic fertilizer with 2∶1（T2）, 1∶1（T3） and 1∶2（T4） and only organic fertilizer（T5）. The abundances and functions of nitrifiers and denitrifiers were quantified, and the abundances of denitrifiers and ammonia oxidizing microorganisms by quantitative PCR techniques, and denitrification capacity, N2 O/（N2 O＋N2） ratio, soil respiration, nitrification potential, relative contributions of ammonia oxidizing archaea（AOA） and ammonia oxidizing bacteria（AOB） to nitrification potential were measured.【Results】The nitrification potential of the T1 and T5 was higher than those of the other treatments. Increased inorganic fertilizer ratio could significantly increase the abundance of AOA and its contribution to nitrification, compared to the increased organic fertilizer ratio. The denitrification capacity and soil respiration were increased with the organic fertilizer increasing, and the denitrification capacity and soil respiration of T5 were significantly higher than those of the other treatments. The abundances of nir S and nos Z-type denitrifiers were increased with the organic manure increasing, while the abundance of nir K-type denitrifiers was decreased. The denitrification capacity was positively correlated with the abundances of nir S or nos Z-type denitrifiers, organic matter and dissolved organic carbon, respectively. However, there was no significant correlation between the denitrification capacity and nir K-type denitrifier abundance.【Conclusions】Our findings suggested that proper combined application of organic and inorganic fertilizers could decrease the nitrification potential, and regulate the role of AOA and AOB in nitrification process and effectively reduce soil denitrification loss, compared to the application of only inorganic or organic fertilizer.