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Low N2O emissions from wheat in a wheat-rice double cropping system due to manure substitution are associated with changes in the abundance of functional microbes
Agriculture, Ecosystems & Environment ( IF 6.6 ) Pub Date : 2021-01-20 , DOI: 10.1016/j.agee.2021.107318
Delei Kong , Yaguo Jin , Kai Yu , Dennis P. Swaney , Shuwei Liu , Jianwen Zou

Fertilization has been shown to affect nitrogen (N) cycling and its related functional microbes in agricultural soils. However, the linkage between soil N2O emissions and N-related functional genes under different fertilization strategies from wheat in a wheat-rice double cropping system is rarely examined. Here, we carried out a two-year field study to examine the response of soil N2O emissions driven by N cycling functional genes [archaeal and bacterial amoA (AOA + AOB), nirS, nirK and nosZ] to different fertilization strategies in a wheat cropland of subtropical China. Three fertilizer treatments were established consisting of chemical phosphorus (P) and potassium (K) fertilizer application (PK), chemical N (urea) and PK fertilizer application (NPK), and chemical NPK fertilizer application with chemical N partially replaced with manure (composted pig manure) (NPKM). Over the two wheat seasons, seasonal total N2O emissions averaged 0.66, 3.60 and 3.11 kg N ha−1 for PK, NPK and NPKM plots, respectively. Relative to the NPK treatment, the NPKM treatment significantly decreased N2O emissions by 14 % without compromising grain yield, with a lowered combined fertilizer-induced emission factor (EF) of 1.02 %. Compared with the PK treatment, N fertilization consistently and significantly increased the abundance of ammonium-oxidation bacteria (AOB), nirS, nirK and nosZ genes. The nosZ gene, which drives N2O reduction during denitrification, showed a greater extent under NPKM with manure N combination. The AOB had a more sensitive response than ammonium-oxidation archaea (AOA) to chemical N fertilization. Seasonal N2O emissions showed significant positive correlations with AOB gene abundance and the ratio of (nirK+nirS)/nosZ, while had a negative correlation with nosZ gene abundance across N fertilized treatments. The N2O-related microbial composition of functional genes was significantly changed by N fertilizer application and also showed contrasting patterns between treatments of chemical N fertilizer with and without manure N substitution. Together, partially replacing chemical N fertilizer with manure reduced N2O emissions from wheat in a wheat-rice double cropping system, mainly through decreasing AOB associated-nitrifying potential, and particularly stimulating N2O reduction.



中文翻译:

在小麦-水稻双作系统中,由于肥料替代而导致的低N 2 O排放与功能性微生物的丰度变化有关

已显示施肥会影响农业土壤中的氮(N)循环及其相关功能微生物。然而,在小麦-水稻双作系统中,不同施肥策略下不同施肥策略下土壤N 2 O排放与N相关功能基因之间的联系很少被研究。在这里,我们进行了为期两年的野外研究,以研究由N个循环功能基因[古细菌和细菌amoA(AOA + AOB),nirSnirKnosZ驱动的土壤N 2 O排放的响应亚热带小麦田中不同的施肥策略。建立了三种肥料处理方法,包括化学磷(P)和钾(K)施肥(PK),化学氮(尿素)和PK施肥(NPK),以及化学氮磷钾施肥,其中化学氮部分替换为粪肥(已混合)猪粪)(NPKM)。在两个小麦季节中,PK,NPK和NPKM图的季节总N 2 O排放平均分别为0.66、3.60和3.11 kg N ha -1。相对于NPK处理,NPKM处理显着降低了N 2在不影响谷物产量的前提下,将O排放量降低了14%,而肥料引起的综合排放因子(EF)降低了1.02%。与PK处理相比,氮肥持续且显着增加了铵氧化细菌(AOB),nirSnirKnosZ基因的丰度。在反硝化过程中驱动N 2 O还原的nosZ基因在NPKM与肥料N组合下表现出更大的程度。AOB对化学氮肥的反应比铵氧化古细菌(AOA)更为敏感。季节性N 2 O排放与AOB基因丰度和(nirK + nirS的比值)呈显着正相关。)/ nosZ,而与N种受精处理中的nosZ基因丰度呈负相关。施用氮肥显着改变了功能基因的N 2 O相关微生物组成,并且在有肥料和无肥料氮替代的化学氮肥处理之间也显示出不同的模式。总之,在小麦-水稻双作系统中,用肥料部分替代化学氮肥可减少小麦的N 2 O排放,这主要是通过降低AOB相关的硝化潜力,特别是刺激N 2 O的减少。

更新日期:2021-01-21
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