秸秆还田方式对东北黑土氮素矿化和氮循环功能基因的影响

doi:10.3864/j.issn.0578-1752.2025.10.008

摘要/Abstract

摘要：

【目的】探究秸秆不同还田方式对东北黑土氮组分、氮矿化及氮循环功能基因丰度的影响，明晰长期秸秆还田下土壤氮素供应能力及土壤氮循环基因群落结构的变化。【方法】基于东北黑土区秸秆还田长期定位试验，选取玉米连作下的秸秆混合还田（RI）和秸秆覆盖还田（RC）为研究对象，以秸秆移除为对照（CK）。测定土壤氮组分含量，采用间歇淋洗好气培养法对土壤进行氮素矿化培养，采用荧光定量PCR（qPCR）测定土壤中氮循环基因拷贝数。【结果】试验8年后，与CK相比，RC处理提高了土壤表层（0—5 cm）颗粒有机氮（PON）和矿物结合态有机氮（MAON）的含量，分别增加了0.21和0.27 g·kg^-1，而RI处理仅使土壤中MAON含量提高了0.13 g·kg^-1（P<0.05）。秸秆还田（RI和RC）土壤中微生物量氮（MBN）含量显著增加了1.4—2.8倍（P<0.05），RI处理具有较高的铵态氮（NH₄⁺）和可溶性有机氮（DON）含量，RC处理的硝态氮（NO₃^-）含量最低。与CK相比，秸秆还田土壤氮矿化量显著提升25.3%—83.2%（P<0.05），各处理土壤氮矿化量由大到小排序为：RC、RI、CK。采用一级反应动力学模型对土壤氮矿化过程进行拟合发现，秸秆还田显著提高了土壤氮矿化势（N₀）和矿化速率常数（k）（P<0.05），且以RC处理为最高，N₀和 k分别达到了199.8 mg·kg^-1和0.31 mg·kg^-1·d^-1。随机森林分析表明，PON、MBN和NO₃^-3个氮组分对N₀影响较大。此外，与秸秆移除相比，秸秆还田的nifH、AOB和nirS基因丰度均显著升高，而秸秆还田的AOA和nirK基因丰度则均显著下降（P<0.05），表明秸秆还田改变了土壤氮循环功能基因群落结构。冗余分析（RDA）发现，秸秆不同还田方式土壤氮循环基因群落结构变化受到土壤中不同氮组分的影响。【结论】长期秸秆覆盖还田土壤有机氮含量和氮素矿化潜力最高，有利于土壤氮库提升及保证作物生长过程中氮素供应，可为东北黑土区农田化学氮肥减施提供更大可能。

关键词: 秸秆还田, 东北黑土, 氮组分, 氮矿化, 氮循环功能基因

Abstract:

【Objective】 This study aimed to explore the effects of different residue return methods on nitrogen fractions, nitrogen mineralization and nitrogen-cycling genes in black soil of Northeast China, and to clear the soil nitrogen supply capacity and the change of soil nitrogen cycling gene community structure under long-term residue return. 【Method】 Based on the long-term experiment of black soil in Northeast China, the residue incorporated into soil (RI) and the residue covered on soil surface (RC) under monoculture maize were selected, with residue removed as control (CK). Nitrogen content in soil fractions were measured, soil nitrogen mineralization incubation was conducted by using leaching incubation at intervals, and fluorescence quantitative PCR (qPCR) was used to determine the copy number of nitrogen-cycling genes in soil. 【Result】 After 8-year experiment, compared with CK, RC significantly increased the content of particulate organic nitrogen (PON)(0.21 g·kg^-1) and mineral-associated organic nitrogen (MAON) (0.27 g·kg^-1) in surface (0-5 cm) soil, whereas RI only increased the content of MAON (0.13 g·kg^-1) in soil (P<0.05). Residue return (RI and RC) markedly increased the microbial biomass nitrogen (MBN) in soil by 1.4-2.8 times (P<0.05), the RI had higher content of ammonium nitrogen (NH₄⁺) and dissolved organic nitrogen (DON), while the RC had the lowest content of nitrate nitrogen (NO₃^-). In comparison with CK, residue return significantly enhanced soil nitrogen mineralization amount by 25.3%-83.2% (P<0.05), taking the descending order of RC>RI>CK. Residue return remarkably increased the potential of soil nitrogen mineralization (N₀) and mineralization rate constant (k) (P<0.05) by using a first-order reaction kinetics model, both showing the highest values under RC, with N₀ and k reached 199.8 mg·kg^-1 and 0.31 mg·kg^-1·d^-1, respectively. Random forest analysis indicated that PON, MBN, and NO₃^- had greater impacts on N₀. In addition, the abundance of nifH, AOB and nirS genes under residue return were enhanced and the abundance of AOA and nirK genes under residue return were declined in comparison with residue removed (P<0.05), which indicated that residue return could change the structure of soil nitrogen-cycling genes communities. Redundancy analysis (RDA) result showed that the changes of soil microbial community structure were affected by different nitrogen fractions under different residue return methods. 【Conclusion】 Long-term residue covered on soil surface had the highest organic nitrogen content and nitrogen mineralization potential in soil. It was beneficial to improve soil nitrogen pools and to ensure the supply of nitrogen required for plant growth, which provided greater possibility for reducing the application of chemical nitrogen fertilizer in cropland in black soil of Northeast China.

Key words: residue return, black soil of Northeast China, nitrogen fractions, nitrogen mineralization, N-cycling functional genes

张旸, 高燕, 张延, 黄丹丹, 陈学文, 张士秀, 梁爱珍. 秸秆还田方式对东北黑土氮素矿化和氮循环功能基因的影响[J]. 中国农业科学, 2025, 58(10): 1958-1968.

ZHANG Yang, GAO Yan, ZHANG Yan, HUANG DanDan, CHEN XueWen, ZHANG ShiXiu, LIANG AiZhen. Effects of Residue Return Methods on Nitrogen Mineralization and N-Cycling Functional Genes in Black Soil of Northeast China[J]. Scientia Agricultura Sinica, 2025, 58(10): 1958-1968.

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基因名称 Gene appellation	氮循环中作用 Function in N-cycling	引物名 Primer name	引物序列 Primer sequence (5'-3')
nifH	固氮作用 N fixation	nifH-F	AAAGGYGGWATCGGYAARTCCACCAC
nifH	固氮作用 N fixation	nifH-R	TTGTTSGCSGCRTACATSGCCATCAT
Arch-amoA	硝化作用 Nitrification	Arch-amoAF	STAATGGTCTGGCTTAGACG
Arch-amoA	硝化作用 Nitrification	Arch-amoAR	GCGGCCATCCATCTGTATGT
AmoA	硝化作用 Nitrification	amoA-1F	GGGGTTTCTACTGGT GGT
AmoA	硝化作用 Nitrification	amoA-2R	CCCCTCKGSAAAGCCTTCTTC
nirS	反硝化作用 Denitrification	Cd3aF	GTSAACGTSAAGGARACSGG
nirS	反硝化作用 Denitrification	R3cdR	GASTTCGGRTGSGTCTTGA
nirK	反硝化作用 Denitrification	F1aCu	ATCATGGTSCTGCCGCG
nirK	反硝化作用 Denitrification	R3Cu	GCCTCGATCAGRTTGTGGTT

处理 Treatment	颗粒有机氮 PON (g·kg^-1)	矿物结合态有机氮 MAON (g·kg^-1)	铵态氮 NH₄⁺(mg·kg^-1)	硝态氮 NO₃^-(mg·kg^-1)	可溶性有机氮 DON (mg·kg^-1)	微生物量氮 MBN (mg·kg^-1)
CK	0.12±0.01b	1.61±0.02c	3.07±0.09b	1.55±0.15b	3.15±0.12b	16.39±0.91c
RI	0.12±0.01b	1.75±0.03b	5.17±0.49a	2.55±0.24a	5.43±0.53a	23.09±0.46b
RC	0.33±0.04a	1.88±0.04a	2.63±0.04b	0.75±0.07c	2.32±0.25b	45.69±1.77a

处理 Treatment	氮矿化势 N₀ (mg·kg^-1)	矿化速率常数 k (mg·kg^-1·d^-1)	决定系数 R²
CK	120.8±3.43 c	0.019±0.001 b	0.96
RI	138.9±2.26 b	0.026±0.001 a	0.93
RC	199.8±2.06 a	0.031±0.001 a	0.94

处理 Treatment	nifH基因拷贝数 nifH copy number (×10⁷ copies·g^-1 soil)	AOA基因拷贝数 AOA copy number (×10⁷ copies·g^-1 soil)	AOB基因拷贝数 AOB copy number (×10⁷ copies·g^-1 soil)	nirS基因拷贝数 nirS copy number (×10⁷ copies·g^-1 soil)	nirK基因拷贝数 nirK copy number (×10⁷ copies·g^-1 soil)
CK	2.24±0.19c	10.91±0.46a	1.83±0.16b	1.73±0.24c	6.83±0.43a
RI	3.83±0.42b	5.32±0.31b	2.05±0.33b	3.45±0.35b	1.28±0.01b
RC	5.07±0.37a	3.70±0.30c	3.09±0.31a	5.73±0.73a	1.76±0.05b

土壤氮组分 Soil N fraction	氮矿化势 N₀		nifH		AOA		AOB		nirS		nirK
土壤氮组分 Soil N fraction	R	P	R	P	R	P	R	P	R	P	R	P
颗粒有机氮 PON	0.90	0.00	0.77	0.01	-0.56	0.09	0.64	0.05	0.88	0.00	-0.36	0.31
矿物结合态有机氮 MAON	0.81	0.01	0.78	0.01	-0.80	0.01	0.59	0.08	0.86	0.00	-0.71	0.02
铵态氮 NH₄⁺	-0.41	0.25	0.01	0.99	-0.16	0.68	-0.47	0.18	-0.15	0.69	-0.39	0.27
硝态氮 NO₃^-	-0.66	0.04	-0.27	0.48	0.15	0.69	-0.48	0.18	-0.39	0.27	-0.10	0.79
可溶性有机氮 DON	-0.47	0.18	-0.14	0.70	-0.02	0.96	-0.24	0.53	-0.29	0.44	-0.30	0.42
微生物量氮 MBN	0.97	0.00	0.79	0.01	-0.80	0.01	0.70	0.02	0.84	0.00	-0.61	0.07