施氮量对农田土壤有机氮组分及酶活性的影响

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焦亚鹏¹, 齐鹏^,¹^,²^,³, 王晓娇¹^,⁴, 武均¹^,²^,³, 姚一铭¹, 蔡立群¹^,²^,³, 张仁陟¹^,²^,³

¹ 甘肃农业大学资源与环境学院,兰州 730070;

² 甘肃农业大学甘肃省干旱生境作物学重点实验室,兰州730070;

³ 甘肃省节水农业工程技术研究中心,兰州730070;

⁴ 甘肃农业大学管理学院,兰州 730070

Effects of Different Nitrogen Application Rates on Soil Organic Nitrogen Components and Enzyme Activities in Farmland

JIAO YaPeng¹, QI Peng^,¹^,²^,³, WANG XiaoJiao¹^,⁴, WU Jun¹^,²^,³, YAO YiMing¹, CAI LiQun¹^,²^,³, ZHANG RenZhi¹^,²^,³

¹ College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070;

² Gansu Provincial Key Laboratory of Arid Land Crop Science, Gansu Agricultural University, Lanzhou 730070;

³ Gansu Engineering Research Center for Agriculture Water-Saving, Lanzhou 730070;

⁴ College of Management, Gansu Agricultural University, Lanzhou 730070

通讯作者: 齐鹏,E-mail：gsauqip@163.com

责任编辑: 杨鑫浩
收稿日期:2019-09-1网络出版日期:2020-06-16

基金资助:

甘肃农业大学学科建设基金.GAU-XKJS-2018-205
甘肃农业大学盛彤笙基金.GSAU-STS-1706
青年研究生导师扶持基金.GAU-QNDS-201704
国家自然科学基金项目.31571594
国家自然科学基金项目.41661049

Received:2019-09-1Online:2020-06-16
作者简介 About authors
焦亚鹏,E-mail：jypm1015@163.com。

摘要
【目的】探讨不同施氮量条件下土壤氮素转化酶活性和有机氮组分含量的变化规律,并分析氮素转化酶活性与各有机氮组分之间的关系,为陇中黄土高原旱作农业区合理制定施肥量和施肥方案提供参考依据。【方法】基于设置在陇中黄土高原定西市李家堡镇麻子川村的不同施氮量（0（CK）、52.5（N1）、105（N2）、157.5（N3）、210（N4）kg N·hm^-2）春小麦长期定位试验,收获后使用Bremner法测定0—40 cm土层中有机氮组分含量,以及4种氮素转化相关酶的活性。【结果】土壤有机氮组分分配比例顺序为氨基酸态氮>酸解铵态氮>酸解未知态氮>氨基糖态氮,同一土层随着施氮量的增加土壤有机碳、全氮、酸解总氮、氨基酸态氮、酸解铵态氮和脲酶活性、蛋白酶活性均呈先增大后降低的趋势,除全氮外其余都在N2处理时最大,全氮含量在N3处理时达到最大;同一处理不同土层间均随土层加深而降低。冗余分析结果表明,全氮含量和蛋白酶活性是影响陇中黄土高原农田有机氮组分分布与转化的关键因子;碳氮比与所有有机氮组分均呈负相关,蛋白酶、有机碳和脲酶与氨基酸态氮呈极显著正相关。【结论】综合而言,N2处理土壤供氮潜力最高,全氮和蛋白酶是影响该区春小麦土壤有机氮组分转化的关键因子。氮肥合理施用能明显提高土壤有机氮含量,不同施氮量条件下土壤有机氮组分变化差异明显,改变了氮素相关转化酶的活性。
关键词： 施氮量;春小麦;有机氮组分;酶活性;冗余分析;黄土高原

Abstract

【Objective】 The changes in enzyme activity conversion and soil organic nitrogen components in different nitrogen application rates were studied, and the relationship between enzyme activity and organic nitrogen component was analyzed. It provided a reference for rationally formulating fertilization amount and fertilization plan in the dry farming area of the Loess Plateau. 【Method】 Based on the different nitrogen (N) application rates (0 (CK), 52.5 (N1), 105 (N2), 157.5 (N3), and 210 (N4) kg N·hm^-2) in Mazichuan village, Lijiabao town, Dingxi city, Loess Plateau, a long-term positioning test was set up on a spring wheat field. Bremner’s method was used to determine the content of organic nitrogen in the 0-40 cm soil layer after harvest, and the activities of four nitrogen-related enzymes were also measured. 【Result】 The order of distribution of soil organic nitrogen components was: amino acid nitrogen>acidolyzable ammonia nitrogen>unknown-acidolyzable nitrogen>amino sugar nitrogen. With the increase of N application rate, soil organic carbon, total nitrogen, total acid nitrogen, amino acid nitrogen, acidolyzable ammonium, urease activity and protease activity increased first and then decreased. Except for total nitrogen, all other components reached the maximum value under N2, and the total nitrogen content reached the maximum value under N3. Different soil layers in the same treatment decreased with the increasing soil depths. The results of redundancy analysis indicated that total nitrogen content and protease activity were the key factors affecting the distribution and transformation of organic nitrogen components in the Loess Plateau of Longzhong. C:N ratio was negatively correlated with all organic nitrogen components, while protease, organic carbon and urease were positively correlated with amino acid nitrogen. 【Conclusion】 In general, N2 treatment had the highest nitrogen supply potential, and the total nitrogen was the key factor affecting the transformation of organic nitrogen components in spring wheat in this area. The changes of soil organic nitrogen composition under different nitrogen application rates were obvious, which changed nitrogen in the conversion enzyme activity.

Keywords：nitrogen application rate;spring wheat;organic nitrogen component;enzyme activity;redundancy analysis;Loess Plateau

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本文引用格式
焦亚鹏, 齐鹏, 王晓娇, 武均, 姚一铭, 蔡立群, 张仁陟. 施氮量对农田土壤有机氮组分及酶活性的影响[J]. 中国农业科学, 2020, 53(12): 2423-2434 doi:10.3864/j.issn.0578-1752.2020.12.010
JIAO YaPeng, QI Peng, WANG XiaoJiao, WU Jun, YAO YiMing, CAI LiQun, ZHANG RenZhi. Effects of Different Nitrogen Application Rates on Soil Organic Nitrogen Components and Enzyme Activities in Farmland[J]. Scientia Acricultura Sinica, 2020, 53(12): 2423-2434 doi:10.3864/j.issn.0578-1752.2020.12.010

0 引言

【研究意义】土壤是陆地上各种植物生长的基床,氮素是土壤中影响植物生长和农田生态系统生产力的主要限制因子^[1,2]。氮素在土壤中主要以有机形态存在^[3,4,5],约占土壤全氮的85%—90%,有机氮只有通过矿化转化为无机氮才能被植物吸收利用。土壤有机氮主要包括蛋白质、核酸、氨基酸及氨基糖等^[6],难以分离测定。1965年,BREMNER等^[7]提出用酸解的方法把土壤有机氮分为酸解氮和非酸解氮两大部分,其中酸解性氮中可以鉴别的有机氮化合物主要是氨基酸态氮、氨基糖态氮和铵态氮,还有一些未鉴别的含氮化合物^[8]。土壤酸解铵态氮是可直接供当季作物吸收利用的有效态氮,氨基酸态氮是土壤固持氮的重要储存库,在当季作物生产过程中主要充当过渡氮库的作用^[9]。氨基酸态氮和酸解铵态氮是土壤易矿化有机态氮的源和库^[10]。土壤有机氮不仅可以维持土壤氮素肥力,而且对土壤氮素供应能力具有重要意义^[11]。土壤酶是土壤中重要的生物催化剂,参与土壤中重要营养元素的生物化学循环、土壤有机质及矿物质的转化过程等^[12]。土壤酶对于环境和管理因素引起的变化最为敏感,其高低可以反映土壤养分转化能力的强弱和土壤供应植物根系养分的潜在能力^[13,14]。土壤蛋白酶、脲酶、硝酸还原酶和亚硝酸还原酶是参与土壤氮素转化的关键酶,其活性的高低与土壤氮素转化强度及土壤供氮能力密切相关^[15]。陇中黄土高原旱作农田土壤有机质含量低,氮素供应能力较差,当地农民习惯施用大量氮肥以保证获得较高作物产量,而长期大量氮肥施用不仅不能达到农作物增产增效,而且还会导致氮素的大量残留从而造成经济损失、耕地质量下降和严重的环境问题。施氮量的不同会影响土壤氮素转化酶活性,进而影响土壤氮循环^[16]。因此研究不同施氮量下土壤有机氮组分特征及其影响因素,对于陇中黄土高原旱作农田合理施用氮肥有重要意义。【前人研究进展】施用氮肥可以改变农田土壤有机氮组分,但是对于土壤中不同的氮组分影响不一致。施氮显著提高了土壤酸解总氮的含量,但未酸解态氮含量未明显增加^[3,17];施氮显著提高了酸解铵态氮的含量但降低了氨基糖态氮的含量,氨基酸态氮和酸解未知态氮的含量增加不显著^[14,18];TIAN等^[19]研究发现,氮添加能够降低土壤氨基酸氮含量,增加氨基糖氮含量。施氮改变了土壤酸解有机氮组分的分配比例,其顺序为氨基酸态氮>酸解铵态氮>酸解未知态氮>氨基糖态氮^{[20,21,22,23]},氨基酸态氮、酸解未知态氮和酸解铵态氮是土壤活性氮的主要贡献因子^[3,17,24]。吴汉卿等^[18]研究发现,除氨基糖氮,其余酸解态氮各组分和酸解总氮含量及其占全氮比例均随着土层深度的增加而降低,不同土层含量差异显著。施氮能显著提高脲酶和蛋白酶活性^[25,26],降低硝酸还原酶和亚硝酸还原酶活性^[27],但是对于不同氮素添加水平响应不一致。随着施氮量的增加,脲酶和蛋白酶活性先升高后降低^[24,28],硝酸还原酶活性逐渐增大^[26]。【本研究切入点】综上,施氮对有机氮组分的组成与转换特征已有大量的研究,然而不同施氮量如何影响陇中黄土高原旱作农业区农田土壤有机态氮组分以及土壤氮素转换酶对土壤有机氮组分转化的影响研究较少,须进一步研究加以阐明。【拟解决的关键问题】本研究通过设置在陇中黄土高原定西市李家堡镇麻子川村的长期定位春小麦施氮量试验,测定春小麦农田氮素转化酶（脲酶、蛋白酶、硝酸还原酶和亚硝酸还原酶）活性,并用 BREMNER^[7]提出的酸解法测定土壤不同有机氮组分含量,探讨施氮量对氮素转化酶活性和有机氮组分组成的影响,并分析氮素转化酶活性与各有机氮组分之间的关系,以揭示土壤氮素转化酶活性对土壤有机氮组分的影响特征,为陇中黄土高原旱作农业区合理制定施肥量和施肥方案、优化管理方式,减少肥料浪费和环境污染,提高氮肥利用率,实现增产稳产提供理论依据。

1 材料与方法

1.1 试验地概况

试区位于陇中黄土高原半干旱丘陵沟壑区的甘肃省定西市李家堡镇麻子川村（35°28′ N,104°44′ E）。试区农田土壤为典型的黄绵土,质地均匀、土质绵软。平均海拔 2 000 m,无霜期 140 d,年均日照时数2 476.6 h,年均太阳辐射 594.7 kJ·cm^-2,年均气温 6.4℃,≥0℃积温2 933.5℃,≥10℃积温2 239.1℃,属中温带半干旱区;多年平均降水 390.9 mm,年蒸发量1 531 mm,80%保证率的年降水量为 365 mm,变异系数为 24.3%,为典型的雨养农业区。

1.2 试验设计

试验自 2013 年布设至今,共设 5 个施氮水平：0（CK）、52.5（N1）、105（N2）、157.5（N3）、210（N4）kg·hm^-2,3 次重复,随机区组分布,共计 15 个小区（面积15 m²）,于播种前施肥,不追肥。供试作物为春小麦（定西 40 号）。氮肥为尿素（N 46%）,磷肥为过磷酸钙（P₂O₅ 14%）,各小区均施105 kg·hm^-2。 2017年3月下旬播种,7月下旬收获,播种量187.5 kg·hm^-2,行距 20 cm,播深 7 cm。

1.3 样品采集与分析

在2017年7月下旬,春小麦收获后在整个小区采用“S”型5点取样方法采集0—10、10—20和20—40 cm 3层土样,混匀并挑除动植物残体,立即过2 mm筛,一部分土样低温冷藏（4 ℃）,用于测定土壤酶活性等指标,剩余土样风干后备用。

土壤pH采用水土比2.5﹕1电位法测定^[29];有机碳（soil organic carbon,SOC）采用重铬酸钾-浓硫酸外加热法测定^[29];全氮（total nitrogen,TN）采用H₂SO₄消煮-凯氏定氮法测定^[29];全磷（total phosphorus,TP）采用H₂SO₄-HClO₄酸溶-钼锑抗比色法测定^[29];脲酶（urease,UR）活性采用次氯酸钠-苯酚钠比色法测定^[30];硝酸还原酶（nitrate reductase,NR）采用酚二磺酸比色法测定^[30];亚硝酸还原酶（nitrite reductase,NIR）采用酚二磺酸比色法测定^[30];蛋白酶（proteinase,PR）采用加勒斯江法测定^[31]。

土壤有机氮分级采用BREMNER方法^[7]：酸解总氮（total acidolyzable N,TAN）采用凯氏定氮法测定;氨基酸态氮（amino acid N,AAN）采用茚三酮氧化、磷酸盐-硼酸盐缓冲液蒸馏法测定;酸解铵态氮+氨基糖态氮（acidolyzable ammonia N,AN +amino sugar N,ASN）采用磷酸盐-硼酸盐缓冲液蒸馏法测定;酸解铵态氮采用氧化镁蒸馏法测定;酸解未知态氮（unknown- acidolyzable N,UAN）、未酸解氮（non-acidolyzable N,NAN）和氨基糖态氮则采用差减法求得。

酸解未知态氮=酸解总氮-酸解铵态氮-氨基酸态氮-氨基糖态氮;

未酸解氮=全氮-酸解总氮;

氨基糖态氮=（酸解铵态氮+氨基糖态氮）-酸解铵态氮。

1.4 数据处理

用Excel 2010和SPSS 18.0进行试验数据统计分析,采用单因素方差分析（One-way ANOVA）Duncan法进行多重比较分析,SigmaPlot 14.0作图,用Canoco 5.0软件进行冗余分析（RDA）。

2 结果

2.1 施氮量对土壤有机氮组分含量的影响

由图1可知,连续施用氮肥提高了土壤中酸解总氮的含量,占土壤全氮的74.4%—87.7%,各土层土壤酸解总氮的含量随着施氮量的增加呈先升高后降低的趋势,0—10 cm土层,N2处理含量最高,10—20和20—40 cm土层,N3处理含量最高。相较于CK处理,酸解总氮增加了37.2—230.1 mg·kg^-1。酸解总氮含量随着土层的加深逐渐降低。未酸解氮是土壤氮库中较为稳定的组分,其含量占土壤全氮的12.3%—25.6%,不同处理间变化不显著,随着土层的加深呈先升高后降低的趋势,在10—20 cm土层含量最高。

图1

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图1施氮量对各土壤有机氮组分含量的影响

同一土层不同小写字母表示处理间差异显著（P<0.05）。下同
Fig. 1Influence of soil organic N forms content under different nitrogen rates

Different lower case letters with the same soil layer indicate significant difference among different treatment at the 0.05 level. The same as below

不同施氮量不仅影响了土壤酸解总氮的含量,土壤酸解氮各组分含量也发生了明显变化。土壤氨基酸态氮、酸解铵态氮、氨基糖态氮和酸解未知态氮分别占土壤全氮的24.4%—36.1%、20.3%—30.3%、1.4%—3.6%和16.1%—31. 7%,氮肥添加显著影响了它们的含量。各土层土壤氨基酸态氮和酸解铵态氮含量均随着氮肥投入量的增加呈先升高后降低的趋势,以N2处理的含量最高;氨基糖态氮含量明显增加,0—10 cm土层N4处理含量最高,10—20和20—40 cm土层含量N2处理最高;酸解未知态氮含量明显增加,0—10和20—40 cm土层N4处理的含量最高,10—20 cm土层N3含量最高;较CK处理,其余各处理氨基酸态氮、酸解铵态氮、酸解氨基糖态氮和酸解未知态氮含量分别增加了1.8%—52.8%、1.2%—37.2%、5.9%—108.1%和5.3%—91.0%。不同土层氨基酸态氮和酸解铵态氮含量,随着土层的加深逐渐降低。土壤氨基糖态氮含量随着土层的加深先增加后减小。

由图2可知,在0—10 cm土层,施用氮肥降低了氨基酸态氮和酸解铵态氮占全氮的比例,增加了氨基糖态氮、酸解未知态氮和未酸解氮占全氮的比例;在10—20 cm土层,施氮肥降低了酸解铵态氮和酸解未知态氮占全氮的比例,增加了氨基酸态氮、氨基糖态氮和未酸解氮占全氮的比例;在20—40 cm土层,施氮肥降低了氨基糖态氮、酸解未知态氮和未酸解氮占全氮的比例,而酸解铵态氮和氨基酸态氮占全氮比例变化不显著。不同土层间,没有明显的变化趋势。

图2

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图2施氮量对土壤不同形态氮组分的影响

AN：酸解铵态氮 Acidolyzable ammonia N;ASN氨基糖态氮 Amino sugar N;AAN氨基酸态氮 Amino acid N;UAN:酸解未知氮 Unknown-acidolyzable N;NAN未酸解氮 Non-acidolyzable N
Fig. 2Influence of soil organic N forms under different nitrogen rates

2.2 施氮量对土壤基本化学性质的影响

由表1可知,土壤pH的变化范围8.11—8.41,随着施氮量的增加pH降低,且随着土层的加深pH升高。土壤有机碳含量在7.36—9.45 g·kg^-1间变动,随着土层的加深其含量值降低;在0—10和20—40 cm土层,各处理间有机碳含量随着施氮量的增加呈先增加后降低的趋势,N2处理含量最高;在10—20 cm土层,随着施氮量的增加逐渐增加。各处理土壤全氮均随土层加深而降低;在0—40 cm 各土层,均以N3处理的土壤全氮含量最高,CK处理最低。当施氮量≤157.5 kg·hm^-3（N3）时,土壤全氮含量随施氮量增加而增加;施氮量>157.5 kg·hm^-3（N3）时,土壤全氮含量反而降低。在0—40 cm土层,各处理土壤全氮含量均显著高于CK处理,较CK处理分别升高10.0%—29.9%、14.4%—35.8%和10.8%—28.6%。土壤全磷含量在0.58—0.96 g·kg^-1间变动,随土层加深全磷含量降低,同一土层不同处理随着施氮量的增加全磷含量先降低后增加,N3处理含量最低。土壤C﹕N的变化范围8.71—10.23,同一处理随着土层的加深C﹕N升高。同一土层不同处理均随施氮量的增加先减小后增加,N3处理最低。

Table 1
表1
表1施氮量对土壤基本化学性质的影响
Table 1Influence of soil physical-chemical proprieties under different nitrogen level

处理 Treatment	土层 Soil layers (cm)	pH	有机碳 Soil organic C (g·kg^-1)	全氮 Total nitrogen (g·kg^-1)	全磷 Total phosphorus (g·kg^-1)	C﹕N
CK	0-10	8.24 ± 0.03a	8.31 ± 0.19c	0.84 ± 0.02c	0.93 ± 0.02a	9.63 ± 0.49ab
	10-20	8.37 ± 0.02a	8.02 ± 0.06b	0.79 ± 0.04c	0.79 ± 0.01a	10.11 ± 0.27a
	20-40	8.41 ± 0.03a	7.36 ± 0.25b	0.71 ± 0.01c	0.63 ± 0.00a	10.20 ± 0.38a
N1	0-10	8.18 ± 0.02b	9.38 ± 0.12b	0.92 ± 0.03b	0.92 ± 0.00ab	9.72 ± 0.28a
	10-20	8.27 ± 0.03b	8.67 ± 0.20ab	0.87 ± 0.05bc	0.79 ± 0.01ab	10.23 ± 0.2ab
	20-40	8.35 ± 0.02ab	7.99 ± 0.08ab	0.79 ± 0.01b	0.61 ± 0.00b	9.95 ± 0.13ab
N2	0-10	8.18 ± 0.01b	9.45 ± 0.14a	1.06 ± 0.01a	0.88 ± 0.01bc	8.73 ± 0.27bc
	10-20	8.23 ± 0.04b	8.74 ± 0.30a	1.00 ± 0.04ab	0.79 ± 0.03bc	9.05 ± 0.25bc
	20-40	8.31 ± 0.04bc	8.66 ± 0.14a	0.90 ± 0.02a	0.61 ± 0.01bc	9.23 ± 0.29bc
N3	0-10	8.11 ± 0.01c	9.40 ± 0.06ab	1.09 ± 0.01a	0.85 ± 0.02c	8.71 ± 0.12c
	10-20	8.20 ± 0.01b	8.87 ± 0.07a	1.04 ± 0.02a	0.72 ± 0.01c	8.98 ± 0.17c
	20-40	8.26 ± 0.04bc	8.03 ± 0.21ab	0.91 ± 0.02a	0.58 ± 0.00c	8.91 ± 0.38c
N4	0-10	8.11 ± 0.00c	9.13 ± 0.14ab	1.04 ± 0.01a	0.96 ± 0.02ab	8.77 ± 0.13c
	10-20	8.11 ± 0.02c	9.01 ± 0.17a	0.95 ± 0.05ab	0.81 ± 0.00a	10.22 ± 0.26b
	20-40	8.22 ± 0.01c	7.93 ± 0.01b	0.88 ± 0.01a	0.63 ± 0.01a	9.20 ± 0.12c

The numeric values are all of mean ± standard deviation (n=3); Different letters in the same column mean significant difference at the 0.05 level
表中数值均为平均值±标准差（n=3）;同列不同小写字母表示处理间差异达0.05 显著水平

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2.3 施氮量对土壤氮素转化酶活性的影响

如图3所示,施氮量对土壤脲酶、蛋白酶、硝酸还原酶和亚硝酸还原酶影响显著（P>0.05）。土壤脲酶活性变化范围0.85—1.42 mg glucose·g^-1·24 h^-1,随着土层的加深同一处理土壤脲酶活性逐渐降低,同一土层不同处理脲酶活性随着施氮量的增加先增加后减小,N2处理活性最高。土壤蛋白酶活性变化规律与脲酶一致,变化范围0.38—0.48 mg glycine·g^-1·24 h^-1。土壤硝酸还原酶活性变化范围0.10—0.26 NO₂^--N mg·g^-1·24 h^-1,连续施氮对硝酸还原酶活性影响显著,没有明显的变化趋势,0—10和10—20 cm土层土壤N2处理活性最高,20—40 cm土层CK处理活性最高。土壤亚硝酸还原酶活性变化范围0.47—0.55 mg NO₂^--N·g^-1·24 h^-1,随着土层的加深其活性逐渐升高;0—10和10—20 cm土层,土壤亚硝酸还原酶活性随着施氮量的增加先增加后降低,N3处理活性最高;20—40 cm土层先降低后增加,N4处理活性最高。

图3

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图3施氮水平对土壤酶活性的影响

Fig. 3Influence of soil enzyme activities under different nitrogen rates

2.4 土壤环境因子与有机氮组分之间的关系

冗余分析（RDA）结果如图 4 所示。环境因子（土壤基本化学性质和氮素转换酶）对有机氮组分的解释率为82.2%,第一轴解释率为32.96%,第二轴解释率为28.88%。从图4可以看出,酸解铵态氮、氨基酸态氮与pH、全氮、全磷、硝酸还原酶、有机碳、蛋白酶和脲酶呈正相关,与亚硝酸还原酶和C﹕N呈负相关。氨基糖态氮与全磷、pH、硝酸还原酶、C﹕N呈负相关,与其全氮、有机碳、蛋白酶、脲酶、亚硝酸还原酶呈正相关。酸解未知态氮与C﹕N和硝酸还原酶呈负相关,与其他环境因子呈正相关。未酸解态氮与亚硝酸还原酶和全氮呈正相关,与其他环境因子呈负相关。全氮是影响有机氮组分变化的最重要因子,对方差的解释率为27.45%;蛋白酶对有机氮组分变化的影响次之,对方差的解释率为22.19%。蛋白酶、脲酶和有机碳与氨基酸态氮呈极显著相关关系。环境变量对有机氮组分方差解释率大小顺序为全氮>蛋白酶>C﹕N>有机碳>脲酶>全磷>pH>亚硝酸还原酶>硝酸还原酶。

图4

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图4土壤基础化学性质和氮素转化酶与氮组分的冗余分析

PR:蛋白酶 Proteinase; UR:脲酶 Urease; NR:硝酸还原酶 Nitrate reductase; NIR:亚硝酸还原酶 Nitrate reductase; SOC:土壤有机碳 Soil organic carbon; TN:全氮 Total nitrogen; TP:全磷 Total phosphorus; C:N:碳氮比 C:N; AN:酸解铵态氮 Acidolyzable ammonia N; ASN氨基糖态氮 Amino sugar N; AAN氨基酸态氮 Amino acid N; UAN:酸解未知氮 Unknown-acidolyzable N; NAN未酸解氮 Non-acidolyzable N; CKA:CK为试验处理, A为0—10 cm土层, B、C 分别为10—20, 20—40 cm土层. CKA:CK is the treatment, A is 0-10 cm soil layer, B, C is 10-20 and 20-40 cm soil layer, respectively
Fig. 4Redundancy analysis of soil chemical properties, enzyme activities and soil organic nitrogen forms

3 讨论

3.1 土壤有机氮组分对施氮量的响应

本研究中,施氮显著提高了土壤酸解总氮的含量,但未酸解态氮含量则未明显增加。贾倩等^[3]对不同氮肥用量水稻-棉花轮作农田的研究也表现出相似结果。本研究中,随着施氮量的增加土壤酸解总氮先增加后降低,这与全氮的变化趋势基本一致。有研究表明^[22],土壤全氮与酸解总氮呈极显著相关关系。姬景红等^[20]发现,当全氮超过一定阈值,酸解总氮随着全氮含量的增加反而降低,减少的土壤有机氮主要转化为难于矿化的稳定态有机氮而保存于土壤中。这说明适量施氮有利于提高氮肥利用率。彭令发等^[32]认为未酸解态氮是以杂环氮或与杂环和芳香环结合态存在。而杂环或芳香环类化合物均为稳定性氮化合物,不易被矿化^[33]。

本研究中,酸解有机氮组分分配比例顺序为氨基酸态氮>酸解铵态氮>酸解未知态氮>氨基糖态氮,这与前人^{[20,21,22,23]}的研究结果一致,说明即使在不同的区域,土壤有机氮组分的分布特征也有一定的共性。党亚爱等^[23]对黄土高原典型土壤氮组分研究表明,氨基酸态氮和酸解铵态氮是土壤中最主要的有机氮形态,氨基酸态氮和酸解铵态氮是土壤易矿化有机态氮的源和库,与土壤的供氮能力密不可分^[34]。本研究中,土壤氨基酸态氮和酸解铵态氮含量均在N2处理达到峰值。这可能是由于长期连续施氮通过影响土壤pH、有机质、全氮含量从而影响土壤微生物活动进而决定有机氮转化过程。近年来有研究发现^[32,35],酸解未知态氮主要由杂环态氮、土壤腐殖质化过程的产物和部分酸解未释放的固定态铵等生物有效性低的物质组成,由于它的矿化速率很低,是土壤酸解有机氮库中难矿化的组分,通常容易在土壤中积聚^[36]。本研究结果表明,随施氮量的增加,酸解未知态氮含量明显增加。这与贾倩等^[3]在不同施氮量水稻-油菜轮作农田的研究结果一致。但王媛等^[37]在不同栽培模式和施氮量对小麦-玉米轮作研究结果表明,施氮量对酸解未知态氮含量无显著影响。这可能由于施肥年限、土壤类型、栽培模式等不同影响土壤微生物活性,从而影响有机氮的分配与转化。

氨基糖态氮占酸解有机氮的比例很低,主要成分为氨基葡萄糖、氨基半乳糖和胞壁酸,主要源于微生物细胞壁的残留物,它反映的是已死亡的土壤微生物积累量而不是现存的微生物量^[3,37-38]。对于氨基糖态氮而言,不同施氮量对其变化很小,但是有所提高,这与很多已报道的研究结果^[3,32,39-40]类似。但是巨晓棠等^[11]在15年有机肥与化肥定位试验耕层土壤有机氮组分研究结果表明施用氮肥显著降低了氨基糖态氮的含量,这与本文的结果并不一致。这可能是由于不同的施氮管理措施、试验的年限、取样方式与研究区域等原因,导致微生物活性不同,进而影响土壤有机氮的分配与转化。

土壤酸解铵态氮和氨基酸态氮是土壤中有效氮的“暂存库”和“缓效库”,其含量的高低直接影响土壤供氮潜力,可作为土壤供氮潜力的表征^[36]。本研究中,N2处理下氨基酸态氮和酸解铵态氮含量最高,这表明N2处理下土壤中活性有机氮含量较高,即土壤供氮潜力较高。因此,科学合理的施氮量对提高该区春小麦农田土壤供氮潜力意义重大。

3.2 土壤氮素转化酶活性对施氮量的响应

土壤酶活性是土壤生物学活性的表现,也是衡量土壤肥力水平的重要指标,能反映土壤养分尤其是N、P转化能力的强弱,但土壤生物活性又受土壤养分状况、土壤质地等因素的影响^[41,42,43]。本研究中,土壤蛋白酶和脲酶活性随施氮量的增加先增长后下降,以N2处理的活性最高,这证明氮素对酶活性的促进作用有一定的限制;郭天财等^[42]、袁玲等^[44]和徐福利等^[45]的研究也表明,随着施氮量的增加,作物根系分泌物增加,土壤微生物数量增加,进一步促进了土壤酶活性增强,从而提高了土壤有机氮的转化,进而提高了土壤肥力。但如果施氮量超过一定阈值,施氮会抑制酶活性。这可能是由于氮肥促进了作物根系代谢,使根系分泌物增多,微生物繁殖加快,而根际微生物通过吸收土壤中的养分,可以形成近根缓效供应的养分库,有利于提高土壤酶活性^[43,46-48],但当施氮量超过一定阈值,过高的氮肥用量会阻碍微生物的合成作用,导致酶活性的减弱^[30]。本研究中,氮肥施用量在0—105 kg N·hm^-2范围内均有利于提高春小麦土壤脲酶和蛋白酶活性。0—10和10—20 cm土层土壤硝酸还原酶和亚硝酸还原酶活性随着施氮量的增加先升高后降低,硝酸还原酶活性以N1最高,亚硝酸还原酶以N3最高;20—40 cm土层不同施氮处理先降低后升高,硝酸还原酶活性以N2最低,亚硝酸还原酶以N3最低。已有研究表明反硝化酶活性主要受土壤温度、水分、氧气、底物浓度和有机碳含量等因素影响^[27,49],陈哲等^[50]研究结果表明,土壤施肥显著增加了土壤反硝化细菌的多样性和丰度,相应提高了反硝化作用,但闫钟清等^[27]对草地不同氮添加的研究结果与本研究的相反,他们发现施氮会降低亚硝酸还原酶的活性,这可能由于不同的地区、作物、栽培方式、施肥方式影响土壤pH和有机质含量和取样时间与方式的不同,从而导致土壤酶活性的不同。DECHARD等^[51]发现,亚硝酸还原酶活性取决于介质中NO₃^-浓度,与NO₃^-浓度呈正相关。本研究中,硝态氮含量随土层的加深而升高,增加了底物浓度从而改变了亚硝酸还原酶的活性。有研究发现,土壤酶活性随着土层深度的增加而降低^[52]。这可能是由于在植物根系周围和根系及有机残体集中的土壤表层有丰富的酶释放源,随着土层的加深植被根系减少,有机质含量降低、土壤动物和微生物种类和数量减少,生理活性降低,随即酶的释放量就会降低^[53,54]。

3.3 影响土壤有机氮分布和转化的因素分析

RDA结果显示,土壤全氮、蛋白酶、有机碳和C﹕N是影响陇中黄土高原春小麦农田土壤有机氮组分变化的关键因子。土壤全氮的质量与数量直接影响到参与氮素矿化的微生物是否容易获得自身分解所需的能源与氮源,进而影响到土壤氮素转化特征^[55]。在农业生态系统中,土壤有机氮的转化过程是由理化过程和微生物过程共同作用的结果。本研究区植物可利用的活性氮库主要以有机态存在,植物和微生物分泌的蛋白酶能将大部分的有机氮转化为可供植物吸收利用的无机氮^[56]。土壤有机碳为土壤微生物生活提供了充足的能量,促进了微生物对土壤有机氮的矿化。碳氮比影响氮素矿化速率^[57],PRESCOTT等^[58]认为当土壤碳氮比小于25﹕1时,土壤中的氮素会出现净矿化。本研究中,土壤碳氮比维持在较低的水平,减弱了微生物的分解能力,土壤有机氮组分与碳氮比呈现出负相关关系。

4 结论

氮肥合理施用是维持或提高土壤肥力的基础。在本研究中,土壤氨基酸态氮、酸解铵态氮随着施氮量的增加先升高后降低,均在N2处理达到最大。在此施氮模式下N2处理土壤供氮潜力最高。根据RDA结果可知,全氮是影响有机氮组分变化的最重要因子,蛋白酶次之;碳氮比与所有有机氮组分均呈负相关,蛋白酶、有机质和脲酶与氨基酸态氮呈极显著正相关。

参考文献原文顺序
文献年度倒序
文中引用次数倒序
被引期刊影响因子

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吕超群, 田汉勤, 黄耀. 陆地生态系统氮沉降增加的生态效应
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人类活动在全球范围内极大地改变着氮素从大气向陆地生态系统输入的方式和速率，人为固定的氮素正在不断积累，并对生态系统的结构和功
能产生显著影响。该文从以下几个方面综述了大气氮沉降增加对陆地生态系统的影响：1)氮输入增加可能影响植物生产力和生态系统碳蓄积能
力，生态系统响应的方向和程度取决于系统的初始氮状况(氮限制或氮饱和)以及当地的植被和土壤特征；2)持续氮输入有可能改变土壤氮循环
过程，降低土壤固持氮的能力，甚至导致土壤酸化、盐基离子损耗，进而影响到土壤有机碳的分解；3)高的氮沉降速率和持续氮输入都可能加
速含氮痕量气体的释放，但其影响程度受生态系统初始状态的影响(例如磷限制和氮限制)；4)氮沉降增加会影响生态系统的物种丰富度、植物
群落结构和动态，促进森林扩张，改变菌根真菌的物种多样性；5)持续氮输入带来的植物群落结构和植物生理特征的变化可能影响昆虫取食特
性，进而通过食物链改变生态系统的营养结构；6) 氮沉降增加对生态系统的影响并不是孤立存在的，它与CO₂浓度升高和O₃浓度变化有协同作
用，但难以从其协同效应中区分出各自的影响。最后，该文总结了我国的氮沉降研究现状，并对今后的研究前景提出了展望。

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高涵, 肖礼, 牛丹, 倪银霞, 黄懿梅. 宁南山区退耕还林还草对土壤氮素组成及其转化酶活的影响
环境科学, 2019,40(8):3825-3832.

[本文引用: 1]

GAO

, XIAO

, NIU

, NI

Y X

, HUANG

Y M

. Effects of converting farmland into forest and grassland on soil nitrogen component and conversion enzyme activity at mountain area of Southern Ningxia
Environmental Science, 2019,40(8):3825-3832. (in Chinese)

[本文引用: 1]

[3]

贾倩, 廖世鹏, 卜容燕, 张萌, 任涛, 李小坤, 丛日环, 鲁剑巍. 不同轮作模式下氮肥用量对土壤有机氮组分的影响
土壤学报, 2017,54(6):1547-1558.

[本文引用: 7]

JIA

, LIAO

S P

, BU

R Y

, ZHANG

, REN

, LI

X K

, CONG

R H

, LU

J W

. Effects of nitrogen application rate on fractionation of soil organic nitrogen relative to crop rotation mode
Acta Pedologica Sinica, 2017,54(6):1547-1558.

[本文引用: 7]

[4]

THOMAS

B W

, WHALEN

J K

, SHARIFI

, CHANTIGNY

, ZEBARTH

B J

. Labile organic matter fractions as early-season nitrogen supply indicators in manure-amended soils
Journal of Plant Nutrition and Soil Science, 2016,179:94-103.

DOI:10.1002/jpln.v179.1 URL [本文引用: 1]

[5]

SHAHID

, NAYAK

A K

, PUREE

, TRIPATHI

, LAL

, GAUTAM

. Carbon and nitrogen fractions and stocks under 41 years of chemical and organic fertilization in a sub-humid tropical rice soil
Soil and Tillage Research, 2017,170:136-146.

DOI:10.1016/j.still.2017.03.008 URL [本文引用: 1]

[6]

SCHULTEN

H R

, SCHNITZER

. The chemistry of soil organic nitrogen: A review
Biology and Fertility of Soils, 1998,26:1-15.

DOI:10.1007/s003740050335 URL [本文引用: 1]

[7]

BREMNER

J M

. Organic forms of nitrogen//BLACK C A. Methods of Soil Analysis. Madison, Wisconsin,
USA: American Society of Agronomy Incorporation, 1965: 1148-1178.

[本文引用: 3]

[8]

张丽敏, 徐明岗, 娄翼来, 王小利, 段建军, 李渝, 蒋太明, 段英华. 长期有机无机肥配施增强黄壤性水稻土有机氮的物理保护作用
植物营养与肥料学报, 2015,21(6):1481-1486.

DOI:10.11674/zwyf.2015.0613 URL [本文引用: 1]

目的土壤有机碳物理-化学联合分组方法很好地联系了有机碳的多种稳定机制,成为深入研究土壤有机碳组分特征的有效手段。本研究旨在利用该方法研究长期施肥对黄壤性水稻土有机氮组分特征的影响,为合理施肥提供理论依据。方法基于南方黄壤性水稻土18年长期施肥定位试验,分析了不同施肥处理土壤有机氮组分含量及分配比例的变化。试验处理包括不施肥对照(CK)、单施化肥(NPK)、单施有机肥(M)、无机肥配施低量有机肥(0.5MNPK)和无机肥配施高量有机肥(MNPK)。结果单施化肥处理(NPK)水稻土总有机氮及各组分有机氮含量与不施肥对照相比无显著变化,施用有机肥处理(M、 0.5MNPK、 MNPK)则显著提高了土壤总有机氮、游离态粗颗粒、物理保护、化学保护及生物化学保护有机氮含量,提高幅度分别为27%~51%、 23%~39%、 128%~274%、 29%~42%和13%~28%,以有机无机肥配施最为显著,但降低了游离态细颗粒有机氮含量。在各个氮组分中,游离态颗粒有机氮占总有机氮比例最高(46%~50%),物理保护有机氮比例最低(2%~6%)。与不施肥(CK)及单施化肥处理(NPK)相比,有机肥处理(M、 0.5MNPK、 MNPK)提高了土壤物理保护有机氮的分配比例。结论长期施肥土壤各组分有机氮及总有机氮两两之间均呈显著相关关系,只有游离细颗粒有机氮与物理保护有机氮呈负相关关系。长期施用有机肥,极大改善土壤团聚体结构,促进游离细颗粒有机氮的包裹,进而提高物理保护有机氮的相对比例,土壤有机氮的物理保护作用相对增强。因此,有机无机肥配施是提高稻田土壤有机氮含量的最有效措施。

ZHANG

L M

, XU

M G

, LOU

Y L

, WANG

X L

, DUAN

J J

, LI

, JIANG

T M

, DUAN

Y H

. Combined application of chemical and organic fertilizers long-term increase physical protection of nitrogen in yellow paddy soil
Journal of Plant Nutrition and Fertilizer, 2015,21(6):1481-1486. (in Chinese)

DOI:10.11674/zwyf.2015.0613 URL [本文引用: 1]

Lü

H J

, HE

, ZHAO

, ZHANG

, XIE

, HU

G Q

. Dynamics of fertilizer-derived organic nitrogen fractions in an arable soil during a growing season
Plant and Soil, 2013,373(1/2):595-607.

DOI:10.1007/s11104-013-1824-8 URL [本文引用: 1]

[10]

WERDIN-PFISTERER

N R

, KIELLAND

, BOONE

R D

. Soil amino acid composition across a boreal forest successional sequence
Soil Biology & Biochemistry, 2009,41(6):1210-1220.

DOI:10.1016/j.soilbio.2009.03.001 URL [本文引用: 1]

[11]

巨晓棠, 刘学军, 张福锁. 长期施肥对土壤有机氮组成的影响
中国农业科学, 2004(1):87-91.

URL [本文引用: 2]

采用 196 5年Bremner提出的土壤有机氮分级方法 ,对 15年有机肥与化肥定位试验中的耕层土壤有机氮组成进行了分级。结果表明 ,长期施用化肥和有机肥对土壤全氮和土壤有机氮组成有显著影响。与单施氮磷化肥相比 ,有机肥与化肥配合施用显著提高了土壤全氮、酸解性氮与非酸解性氮的含量 ;但在酸解性氮中 ,氨基糖氮显著下降 ,而酸未知氮极显著增加。与不施氮相比 ,施用氮肥显著提高了土壤全氮、酸解性氮与非酸解性氮的含量 ;在酸解性氮中 ,氮肥显著提高了氨态氮的含量但降低了氨基糖氮的含量 ,氨基酸态氮和酸未知氮的含

X T

, LIU

X J

, ZHANG

F S

. Effects of long-term fertilization on soil organic nitrogen fractions
Scientia Agricultura Sinica, 2004(1):87-91. (in Chinese)

URL [本文引用: 2]

DICK

W A

. Influence of long-term tillage and crop rotation combination on soil enzyme activities
Soil Science Society of America Journal, 1984,48:569-574.

DOI:10.2136/sssaj1984.03615995004800030020x URL [本文引用: 1]

[13]

姜小凤, 王淑英, 丁宁平, 樊廷录, 张平良, 郭建国, 李倩, 苏敏. 施肥方式对旱地土壤酶活性和养分含量的影响
核农学报, 2010,24(1):136-141.

URL [本文引用: 1]

为了明确不同施肥方式下旱地土壤酶活性与养分间的相互关系，以30年（1979-2008）肥料长期定位试验地为基础，研究了不同施肥方式下旱地小麦田耕层（0～20cm）土壤酶活性与养分的变化趋势及其相关性。结果表明，相比单施氮肥和氮磷配施，小麦秸秆与氮磷配施的土壤蔗糖酶、磷酸酶、过氧化物酶和多酚氧化酶活性以及土壤中全氮、全磷和有机质含量提高，但全钾含量降低。相关分析表明：土壤中的蔗糖酶活性与磷酸酶和过氧化物酶的活性，磷酸酶与过氧化物酶活性之间相关显著，相关系数依次为0.6747、0.5878、0.6414（n=9），其余酶活性之间相关不显著。土壤蔗糖酶、过氧化物酶活性与土壤全氮含量，土壤磷酸酶活性与土壤全磷和有机质含量高度正相关，相关系数分别为 0.9969、0.9997、0.9998、0.9863（n=9）；多酚氧化酶活性与土壤中的全磷和有机质含量密切负相关，相关系数分别为0.9945、0.9587（n=9），而蔗糖酶、磷酸酶、过氧化物酶和多酚氧化酶活性与土壤中的全钾含量相关性较低。

JIANG

X F

, WANG

S P

, DING

N P

, FAN

T L

, ZHANG

P L

, GUO

J G

, LI

, SU

. Effect of different fertilization on soil enzyme activity and nutrients
Journal of Nuclear Agricultural Sciences, 2010,24(1):136-141. (in Chinese)

URL [本文引用: 1]

王树起, 韩晓增, 乔云发, 王守宇, 李晓慧. 不同土地利用和施肥方式对土壤酶活性及相关肥力因子的影响
植物营养与肥料学报, 2009,15(6):1311-1316.

DOI:10.11674/zwyf.2009.0610 URL [本文引用: 2]

Soil enzymes play an essential role in catalyzing reactions necessary for the decomposition of organic matter and nutrient cycling in ecosystems, involving a range of plants, microorganisms, animals and their debris. In this paper, black soil samples at the depth of 0-20 cm were collected from the Hailun Agricultural Ecology Station of Chinese Academy of Sciences to study the effects of different land uses and fertilization systems on urease, invertase, phosphatase, and catalase activities, total carbon (TC), nitrogen (TN), alkaline hydrolytic nitrogen, available P and available K. The results showed that soil enzymes activity, TC, TN alkaline hydrolytic nitrogen, available P and available K in both clover land and fallow land significantly increased compared with bald land, in which urease activity increased by 24.5% and 25.0%, invertase activity 18.4% and 18.9%, phosphatase activity 54.6% and 50.4% and catalase activity 8.52% and 59.3%, TC and TN increased by 13.8%, 13.0% and 36.8%, 33.7%, respectively. However, there was no significant difference between clover land and fallow land. There was a significant difference of soil enzymes activities, TC, TN and available nutrients contents among the treatments under different fertilization systems, which followed same order: nitrogen, phosphorus and potassium fertilizers plus organic manure (NPKOM) > nitrogen, phosphorus and potassium fertilizers plus straw (NPKST) > nitrogen, phosphorus and potassium fertilizers combination (NPK) > control (CK). Fertilization, especially organic manure application, could significantly increased soil enzymes activities, TC, TN and available nutrients contents. These results suggested that black soil fertility and quality could be improved either by natural or artificial reclamation or by fertilization.

WANG

S Q

, HAN

X Z

, QIAO

Y F

, WANG

S Y

, LI

X H

. Effects of land uses and fertilization systems on soil enzyme activities and nutrients
Plant Nutrition and Fertilizer Science, 2009,15(6):1311-1316. (in Chinese)

DOI:10.11674/zwyf.2009.0610 URL [本文引用: 2]

杨万勤, 钟章成, 陶建平, 何维明. 缙云山森林土壤酶活性与植物多样性的关系
林业科学, 2001(4):124-128.

DOI:10.11707/j.1001-7488.20010420 URL [本文引用: 1]

By the methods of sampling soil profiles which A,B,and C represent humus horizons,illuvial horizons,and parent materials horizons respectively,relationships between the activities of soil enzymes (which include catalase,invertase,protease,and acid phosphatase) and plant species diversity in three secondary successional plant communitites of forest ecosystem in Mt.Jinyun were studied in this paper.Results showed that different degree′s correlations existed between soil enzymic activities and plant species diversity indice (PSDI) which included Shannon-Wiener H′index and Hill′s species diversity indice family N_A,moreover,the degree of correlation depended on the horizon of soils,the type of enzymes,and the life form of plants (i.e.,tree,or shrub or grass).The degree of correlation between PSDI and soilenzymic activities decreased by the orders of A→B→C.The most significant correlation with PSDI was the activity of soil catalase,and in turn,was the activity of soil invertase,On the whole,the correlation between soil enzymic activities and tree layer′s PSDI was the most evident.Tree layer′s PSDI were positively and significantly (P<0.05) or very significantly (P<0.01) correlated with the activities of catalase and invertase of A and B horizons,and of protease and acid phosphatase of A horizons.Grass layer′s PSDI were also positively and significantly (P<0.05) correlated with the activities of catalase and invertase of A horizons.Shrub layer′s PSDI were not significantly correlated with soil enzymic activities.

YANG

W Q

, ZHONG

Z C

, TAO

J P

, HE

W M

. Study on relationship between soil enzymic activities and plant species diversity in forest ecosystem
Scientia Silvae Sinicae, 2001(4):124-128. (in Chinese)

DOI:10.11707/j.1001-7488.20010420 URL [本文引用: 1]

丁效东, 闫慧峰, 张士荣, 陈伟贤, 郭俊杰, 魏彬, 王军. 有机肥C/N优化下氮肥运筹对烟株根际无机氮和酶活性的影响
中国烟草科学, 2016,37(1):26-31.

[本文引用: 1]

DING

X D

, YAN

H F

, ZHANG

S R

, CHEN

W X

, GUO

J J

, WEI

, WANG

. The effect of nitrogen management on Nmin and enzyme activities in rhizosphere soil of flue-cured tobacco under the optimization of C/N with organic fertilizer
Chinese Tobacco Science, 2016,37(1):26-31. (in Chinese)

[本文引用: 1]

[17]

李世清, 李生秀, 邵明安, 郭大勇. 半干旱农田生态系统长期施肥对土壤有机氮组分和微生物体氮的影响
中国农业科学, 2004,37(6):859-864.

URL [本文引用: 2]

在半干旱农田生态系统红油土上20年的肥料定位试验表明,施用秸秆和厩肥会显著改变耕层土壤有机氮组分和微生物体氮。施肥后酸解性氮的含量及比例明显增加,非酸解性氮含量下降。酸解性氮在不施肥时含量最低(646.3　mgN·kg-1),其次为施用化肥(684.3　mgN·kg-1),同时施用秸秆和化肥居中(794.1～950　mgN·kg-1),施用厩肥和化肥最高(1 103.2　mgN·kg-1)。各处理中,酸解性氮是土壤全氮的主体,占全氮的 73.4%～82.6%,这一比例从仅施化肥、对照、化肥+ 低量秸秆、化肥

S Q

, LI

S X

, SHAO

M A

, GUO

D Y

. Effects of long-term application of fertilizers on soil organic nitrogen components and microbial biomass nitrogen in semiarid farmland ecological system
Scientia Agricultura Sinica, 2004,37(6):859-864. (in Chinese)

URL [本文引用: 2]

吴汉卿, 杜世宇, 高娜, 张玉玲, 邹洪涛, 张玉龙, 虞娜. 水氮调控对设施土壤有机氮组分、全氮和矿质氮的影响
水土保持学报, 2017,31(6):212-219.

[本文引用: 2]

H Q

, DU

S Y

, GAO

, ZHANG

Y L

, ZOU

H T

, ZHANG

Y L

, YU

. Effects of water and nitrogen regulation on soil organic nitrogen fractions, total nitrogen and mineral nitrogen in greenhouse soil
Journal of Soil and Water Conservation, 2017,31(6):212-219. (in Chinese)

[本文引用: 2]

[19]

TIAN

, WEI

, CONDRON

L M

, CHEN

Z H

, XU

Z W

, FENG

, CHEN

L J

. Effects of elevated nitrogen and precipitation on soil organic nitrogen fractions and nitrogen-mineralizing enzymes in semi-arid steppe and abandoned cropland
Plant and Soil, 2017,417(1/2):217-229.

DOI:10.1007/s11104-017-3253-6 URL [本文引用: 1]

[20]

姬景红, 张玉龙, 黄毅, 虞娜, 张玉玲. 灌溉方法对保护地土壤有机氮组分及剖面分布的影响
水土保持学报, 2007(6):99-104.

URL [本文引用: 3]

用Bremner有机氮分组法测定了连续7年采用不同灌溉方法灌溉的保护地土壤各剖面层次有机氮组分含量。结果表明,土壤全氮及有机氮各组分含量均随土层深度的增加而降低,但有机氮各组分占全氮的比例随土层深度增加的变化却无明显规律。用3种灌溉方法灌溉,不同土层间土壤有机氮各组分含量的差异主要存在于0~50 cm土层,50 cm以下差异很小;相同土层,土壤有机态氮含量均以酸解氮为主,且酸解氮中各组分绝对含量和相对含量的大小排列顺序均为,未知态氮>氨态氮>氨基酸态氮>氨基糖态氮。在0~80 cm土层,土壤酸解氮占全氮的比例大多在58%~60%之间,只有渗灌处理0~10 cm,10~20 cm及沟灌处理0~10 cm土层酸解氮占全氮的比例较低,分别为34.21%,50.75%和48.02%;而非酸解氮占全氮的比例大多在32%~36%之间。3种灌溉方法相比较,除个别层次外,酸解氮中氨基酸态氮、氨基糖态氮及氨态氮占全氮的比例在各土层中滴灌和渗灌处理均高于沟灌处理,而酸解未知态氮和非酸解氮占全氮的比例则为沟灌处理高于滴灌和渗灌处理。

J H

, ZHANG

Y L

, HUANG

, YU

, ZHANG

Y L

. Effect of different irrigation methods on forms and profile distribution of soil organic nitrogen in protected field
Journal of Soil and Water Conservation, 2007(6):99-104. (in Chinese)

URL [本文引用: 3]

STEVENSON

F J

. Nitrogen in agricultural soils
Madisone Wisconsin: American Society of Agronomy, 1982.

[本文引用: 2]

[22]

吴汉卿, 杜世宇, 王丹阳, 薛飞, 张玉玲, 邹洪涛, 张玉龙, 虞娜. 设施土壤有机氮组分及番茄产量对水氮调控的响应
植物营养与肥料学报, 2019,25(5):805-813.

[本文引用: 3]

H Q

, DU

S Y

, WANG

D Y

, XUE

, ZHANG

Y L

, ZOU

H T

, ZHANG

Y L

, YU

. Response of soil organic nitrogen fractions and tomato yield to irrigation and nitrogen fertilization in greenhouse
Journal of Plant Nutrition and Fertilizers, 2019,25(5):805-813. (in Chinese)

[本文引用: 3]

[23]

党亚爱, 王国栋, 李世清. 黄土高原典型土壤有机氮组分剖面分布的变化特征
中国农业科学, 2011,44(24):5021-5030.

DOI:10.3864/j.issn.0578-1752.2011.24.007 URL [本文引用: 3]

【Objective】 In order to evaluate the effects of location, soil depth and land use on the contents of soil organic nitrogen (N), the size and composition of soil organic N pool were studied using a large variety of soil profiles sampled on the Loess Plateau. 【Method】 Based on different soil types and land-use patterns, 96 soil samples in 8 depth classes（0-10, 10-20, 20-40, 40-60, 60-80, 80-100, 100-120 and 120-140 cm）were collected from different regions on the Loess Plateau. The method of Bremner was used to test the soil organic N content.【Result】Even with the same land use pattern, the content of soil depth-specific total soil hydrolysable N and its components increased from north to south on the Loess Plateau. The proportion of organic N components within total hydrolysable N was stable. However, the proportion of total hydrolysable N in total soil N significantly decreased within 0-40 cm layers and remained stable below 40 cm. The content of four components significantly decreased within 0-40 cm, slightly decreased within 40-80 cm and remained stable below 80 cm. The percentage of organic N components in total hydrolysable N differed among soil types: amino acid-N (39.5%)＞ammonia N(32.3%)＞HUN fraction(25.7%)＞amino sugar-N(2.5%) in Ust-Sandiic Entisols; amino acid-N (36.0%)＞ammonia N (35.6%)＞HUN fraction (25.3%)＞amino sugar-N (3.1%) in Los-Orthic-Entisol; and ammonia N (50.6%)＞amino acid-N (29.0%)＞HUN fraction (17.5%)＞amino sugar-N (2.8%) in Eum-Orthic Anthrosol. Except amino sugar-N, all the soil organic N components within 0-40 cm in grassland were more than those in cropland; however, the inter-layer variation became smaller with the profiles.【Conclusion】From north to south of the Loess Plateau, the content of organic N and its different forms increased, the proportion of organic N component in total hydrolysable N was stable in the same layer under the same land-use patterns. However, the proportion of total hydrolysable N in total soil N decreased. Amino acid-N and ammonia N were the major forms of the soil organic N on the Loess Plateau. Land-use pattern had a great effect on the content and distribution of N. Both organic N and its components in grassland was more than that in cropland.

DANG

Y A

, WANG

G D

, LI

S Q

. The changing characteristics of profile distribution of soil organic nitrogen component of the typical soil types on the Loess Plateau
Scientia Agricultura Sinica, 2011,44(24):5021-5030. (in Chinese)

DOI:10.3864/j.issn.0578-1752.2011.24.007 URL [本文引用: 3]

Y C

, SHEN

Q R

, RAN

. Content and distribution of forms of organic N in soil and particle size fractions after long-term fertilization
Chemosphere, 2003,50(6):739-745.

DOI:10.1016/S0045-6535(02)00214-X URL [本文引用: 2]

Abstract

Most of the N in surface soils occurs in organic forms, and when mineralized it plays a key role in soil fertility and plant nutrition. Our objective was to study the effect of long-term applications of organic manure on the content and distribution of forms of organic N in bulk soil and soil particle size fractions to characterize the inherent soil nitrogen fertility. Five treatments were as follows: (1) CK (no fertilizer and no manure added), (2) mineral fertilizer only, (3) straw + NPK, (4) green manure + NPK and (5) pig manure + NPK. Soil particle size fractions (0–2, 2–10, 10–50 and 50–100 μm) were isolated without chemical pretreatment by ultrasonic dispersion in water followed by sedimentation. The content of total N and forms of organic N in the bulk soil increased after long-term fertilization, and the effect varied with fertilizer type. The plot treated with only mineral fertilizer gave the highest NH₃-N and the lowest amino sugar-N content in all treatments. The highest content of amino sugar-N and amino acid-N was found in the treatment of pig manure + NPK. The content (g kg⁻¹ fraction) of hydrolysable N within size fractions was in the order 0–2>2–10>50–100>10–50 μm, but the contribution of different size fraction to hydrolysable N decreased in the sequence 10–50>0–2>2–10>50–100 μm. Most of the applied mineral fertilizer N that remained in soils was distributed in the particle size fraction < 2 μm while most of the remaining N from manure applied with NPK was transferred into amino sugar-N in each size fraction, and amino acid-N in the size fractions > 2 μm during the process of humification.

[25]

付智丹, 周丽, 陈平, 杜青, 庞婷, 杨文钰, 雍太文. 施氮量对玉米/大豆套作系统土壤微生物数量及土壤酶活性的影响
中国生态农业学报, 2017,25(10):1463-1474.

[本文引用: 1]

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T W

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Chinese Journal of Eco-Agriculture, 2017,25(10):1463-1474. (in Chinese)

[本文引用: 1]

[26]

李珣, 吕小红. 施氮处理对不同株型水稻品种土壤全氮含量及相关酶活性的影响
江苏农业科学, 2017,45(23):55-58.

[本文引用: 2]

, Lü

X H

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[27]

闫钟清, 齐玉春, 彭琴, 董云社, 郭树芳, 贺云龙, 王丽芹, 李兆林. 降水和氮沉降增加对草地土壤酶活性的影响
生态学报, 2017,37(9):3019-3027.

DOI:10.5846/stxb201601260184 URL [本文引用: 3]

为探究降水和氮沉降增加对草地生态系统土壤酶活性的影响，于2014年生长季在内蒙古温带典型羊草草原开展了野外原位控制实验。试验共设置降水（对照，W0，自然降水；W15，增加15%的年均降水量）、施氮（对照，CK，0 kg N hm^-2a^-1；低氮，LN，25 kg N hm^-2a^-1；中氮，MN，50 kg N hm^-2a^-1；高氮，HN，100 kg N hm^-2a^-1）及其交互作用等8个不同的处理水平来模拟降水和氮沉降增加的全球变化情景，分别定量探讨了不同水、氮添加条件下草地表层土壤中与氮循环相关的蛋白酶，脲酶，硝酸还原酶，亚硝酸还原酶活性的月动态变化及其与土壤理化性质之间的相关性。研究结果表明：在自然降水条件下，不同施氮水平蛋白酶、脲酶和硝酸还原酶活性无显著差异，亚硝酸还原酶活性相比于对照显著降低；在增加降水条件下，不同施氮水平对蛋白酶和硝酸还原酶活性未产生显著性影响，高氮水平显著降低脲酶和亚硝酸还原酶活性。不同施氮水平是否添加降水对亚硝酸还原酶活性无影响，而增添降水使低氮处理的蛋白酶活性和中、高氮处理水平的硝酸还原酶活性增加、高氮处理的脲酶活性降低。降水在影响蛋白酶和硝酸还原酶活性方面具有主效应，氮沉降在影响亚硝酸还原酶活性方面具有主效应，而降水和施氮处理未表现出明显地交互作用。土壤亚硝酸还原酶活性与土壤碳氮比和NH₄⁺-N含量极显著正相关，与NO₃^--N含量显著正相关。

YAN

Z Q

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DOI:10.5846/stxb201601260184 URL [本文引用: 3]

肖新, 李英峰, 韩贻涛, 陈世勇, 史亚东, 俞浩, 汪建飞. 尿素施用量对道地药材滁菊土壤微生物活性的影响
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彭令发, 郝明德, 来璐. 长期施肥对土壤有机氮影响研究Ⅰ氮肥及其配施下土壤有机氮组分变化
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试验布置在典型的黄土高原的沟壑区,长武试验示范区,在长期的小麦连作的基础上,通过单施氮肥以及氮肥与其它肥料的配合使用,研究不同施肥对土壤有机氮组分的影响.试验结果表明,长期施肥对土壤铵态氮和氨基糖氮影响较小,而对土壤氨基酸态氮和酸解未知态氮影响较大,特别是化学氮肥和有机肥的配施效果较好.

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L F

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. Studies of long-term fertilization on soil organic n componentsⅠ. The variation of soil organic N components of N fertilizer and its mixture
Research of Soil and Water Conservation, 2003,10(1):53-54. (in Chinese)

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试验布置在典型的黄土高原的沟壑区,长武试验示范区,在长期的小麦连作的基础上,通过单施氮肥以及氮肥与其它肥料的配合使用,研究不同施肥对土壤有机氮组分的影响.试验结果表明,长期施肥对土壤铵态氮和氨基糖氮影响较小,而对土壤氨基酸态氮和酸解未知态氮影响较大,特别是化学氮肥和有机肥的配施效果较好.

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王媛, 周建斌, 梁斌, 刘东娜. 不同栽培模式和施氮量对小麦-玉米轮作体系土壤供氮特性的影响
植物营养与肥料学报, 2010,16(6):1351-1357.

DOI:10.11674/zwyf.2010.0608 URL [本文引用: 2]

A six year positioning experiment of wheat-maize rotation was used to compare the effects of different cultivation patterns and nitrogen application rates on soil N supplying ability. The results show that compared with the conventional control treatment (CC), the contents of total hydrolysable N (THN), microbial biomass nitrogen (SMBN) and mineralized nitrogen potential (N₀) of soil under the straw mulching treatment (SM) are significantly increased, and the fractions of different forms of soil organic nitrogen are enhanced as well. The contents of THN and N₀ are increased under the furrow cultivation pattern (FM) and the increased rates are lower than those of the SM pattern, while the content of SMBN is decreased. The contents of THN, N₀, amino acid N (AAN), amino sugar N (ASN), ammonium N (AN) are also increased under the nitrogen fertilization, while the content of SMBN is decreased, especially for the N 240 kg/ha rate. The interaction between cultivation pattern and nitrogen application rate on fractions of different forms of organic nitrogen in soil is not statistically significant (P>0.05). The correlation analysis results indicate that there are significantly positive correlations between N₀, SMBN, AAN, hydrolysable unidentified N (HUN)(P<0.05), which implies the last three fractions maybe the major contributors to the soil mineralized nitrogen.

WANG

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D N

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Plant Nutrition and Fertilizer Science, 2010,16(6):1351-1357. (in Chinese)

DOI:10.11674/zwyf.2010.0608 URL [本文引用: 2]

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王克鹏, 张仁陟, 索东让. 长期施肥对河西灌漠土有机氮组分及剖面分布的影响
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李萌, 王昌全, 李冰, 杨娟, 李喜喜, 游来勇, 李一丁. 猪粪替代氮肥对稻麦轮作条件下土壤有机氮组分的影响
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郭天财, 宋晓, 马冬云, 王永华, 谢迎新, 岳艳军, 查菲娜. 施氮量对冬小麦根际土壤酶活性的影响
应用生态学报, 2008(1):110-114.

URLPMID:12722451 [本文引用: 2]

From field investigation and laboratory analysis, the relationships among soil enzyme activities, vegetation state and soil chemical properties of coal cinder yard in thermal power station were studied. The results showed that vegetation on coal cinder yard was distributed in scattered patch mainly with single species of plant, and herbs were the dominant species. At the same time, the activity of three soil enzymes had a stronger relativity to environment conditions, such as vegetation state and soil chemical properties. The sensitivity of three soil enzymes to environmental stress was in order of urease > sucrase > catalase. The relativity of three soil enzymes to environmental factor was in order of sucrase > urease > catalase. Because of urease being the most susceptible enzyme to environmental conditions, and it was marked or utmost marked interrelated with vegetation state and soil chemical properties, urease activity could be used as an indicator for the reclamation of wasteland.

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T C

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F N

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Chinese Journal of Applied Ecology, 2008(1):110-114. (in Chinese)

URLPMID:12722451 [本文引用: 2]

曾艳, 周柳强, 黄美福, 黄金生, 韦运兰, 谢如林, 谭宏伟. 不同施氮量对桑园红壤耕层酶活性的影响
生态学报, 2014,34(18):5306-5310.

DOI:10.5846/stxb201405110956 URL [本文引用: 2]

在广西红壤典型气候区研究施用氮肥对桑园土壤过氧化氢酶、脲酶、酸性磷酸酶和转化酶酶活性的影响，为广西红壤区桑园合理施氮和耕地保育提供科学依据。试验设置3个施氮量水平（N₁：120.75 kg N/hm²，N₂：172.5 kg N/hm²，N₃：207 kg N/hm²），在冬季测定不同氮肥处理下耕层土壤酶活性，并与桑叶产量进行相关分析。结果表明，土壤脲酶和转化酶活性均随着施氮量的增加而增加，过氧化氢酶和酸性磷酸酶活性在中等施氮量（N₂处理）下较大。土壤转化酶和脲酶活性呈显著的正相关关系、转化酶和磷酸酶活性呈显著的正相关关系，土壤脲酶、磷酸酶、转化酶活性与桑叶产量呈极显著相关。合理施用氮肥能提高桑园土壤转化酶、磷酸酶、脲酶活性，土壤脲酶和蔗糖酶活性可作为评价桑园土壤肥力质量的指标之一。

ZENG

, ZHOU

L Q

, HUANG

M F

, HUANG

J S

, WEI

Y L

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R L

, TAN

H W

. Effects of nitrogen fertilization on enzyme activities in surface layer of red soil under mulberry cultivation
Acta Ecologica Sinica, 2014,34(18):5306-5310. (in Chinese)

DOI:10.5846/stxb201405110956 URL [本文引用: 2]

袁玲, 杨邦俊, 郑兰君, 刘学成. 长期施肥对土壤酶活性和氮磷养分的影响
植物营养与肥料学报, 1997(4):300-306.

DOI:10.11674/zwyf.1997.0403 URL [本文引用: 1]

Three ten-year fertilization experiments indicate the increment of protease, urease,invertase, phosphatase and hydrogen peroxidase activities in soil by organic-inorganic fertilization. Similarly, the contents of organic matter and nitrogen as well as phosphorus were increased by the fertilization of organic manure mixed with chemical fertilizers together. Positive correlation were found between the activities of protease. ureas and invertase and the contents of NH₄⁺-N and organic matter, also phosphatase and the concentrations of available P and organic matter in soil as well. Thus, it seems reasonable to suggest that a suitable soil environment for crop growth could be produced by long-term fertilization of organic manure supplied with chemical fertilizers. Moreover, the activities of protease, urease and invertase in soil were decreased as rice growing in. contrast to phosphatase which was observed to be highest in the periods of jointing and heading as compared to those in tillering and mature. There also existed positive correlation between the activities of enzymes and the mobilizations of nitrogen and phosphorus in soil in rice growing period.

YUAN

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B J

, ZHENG

L J

, LIU

X C

. Effects of long-term fertilization on soil enzyme activities and nitrogen and phosphorus nutrients
Plant Nutrition and Fertilizer Science, 1997(4):300-306. (in Chinese)

DOI:10.11674/zwyf.1997.0403 URL [本文引用: 1]

徐福利, 梁银丽, 张成娥, 杜社妮, 陈志杰. 施肥对日光温室黄瓜生长和土壤生物学特性的影响
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URL [本文引用: 1]

This paper studied the effect of fertilization on cucumber growth and yield,soil microbial biomass and soil enzyme activities in sunlight greenhouse in Loess Plateau.The results indicated that the growth and yield of cucumber were increased with application of manure and methane.Foliage application reduced the application rate of NP and manure.Fertilization had an obvious effect on the biological characteristics of soil in sunlight greenhouse.The number of bacteria was increased by manure and foliage fertilization,and that of fungi was increased by NP and methane fertilization but decreased by manure fertilization.Fertilization with manure,NP and methane also remarkably increased the number of actinomyces and the activities of urease,phosphatase and sucrase in soil.The activities of soil urease and phosphatase were increased by fertilization of manure,but little effect was found with fertilization of NP and methane.

F L

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Y L

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C E

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S N

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Z J

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URL

Correlation and cluster analyses on the enzyme activities and chemical-biological properties of eight red soils showed that soil urease,invertase,phosphatase and catalase activities correlated significantly with soil organic carbon,total nitrogen and total phosphorous.Similar results of soil fertility evaluation were obtained by using soil enzyme activities and by using soil chemical-biological properties,indicating that soil enzyme activity could be used as an index of evaluating red soil fertility.The enzyme activities of fresh soil were generally greater than those of air-dried sample,and more closely correlated with soil fertility.

XUE

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H Y

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Z L

, HUANG

C Y

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Chinese Journal of Applied Ecology, 2005(8):1455-1458. (in Chinese)

URL

AON

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In land-based wastewater treatment systems (LTS), denitrification is an important nitrogen removal process. We investigated the factors limiting the denitrifying population in a forested LTS, by studying the individual and combined effects of soil aeration, water content, nitrate and carbon on denitrification enzyme activity (DEA). The size of the soil denitrifying population in the LTS appeared to be limited by soil aeration, and limiting oxygen availability increased the denitrifying population above that observed in the field. Furthermore, we found that wastewater irrigation altered the short-term response of denitrifiers to anaerobic soil conditions. Under low oxygen conditions, denitrifiers in the wastewater-irrigated soils produced enzymes sooner and at a greater rate than soils without a history of wastewater irrigation. We propose that the size of the denitrifying population cannot be expected to be large in free-draining, coarsely textured soils even when provided with additional nitrogen and water inputs.

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陈哲, 袁红朝, 吴金水, 魏文学. 长期施肥制度对稻田土壤反硝化细菌群落活性和结构的影响
生态学报, 2009,29(11):5923-5929.

URL [本文引用: 1]

以中国科学院桃源农业生态试验站长期定位施肥试验为平台，研究了3种长期施肥制度（对照不施肥-CK，化学施肥-NPK，化学施肥＋有机肥-NPKOM）下土壤反硝化速率的差异。同时，以硝酸还原酶基因（narG）作为反硝化细菌的功能标志物，分析了施肥对反硝化细菌群落结构和多样性的影响。结果表明，长期施用有机肥的土壤反硝化速率，反硝化菌多样性都高于对照和施用化肥处理。从3个处理的土壤样品中共获得35个narG基因的可操作分类单元（OTU）主要分布在两个簇，与变形菌门（Proteobacteria）和放线菌门（Actinobacteria）的反硝化细菌有一定的亲缘关系，均为首次从土壤中克隆。Shannon多样性指数显示，NPKOM处理的narG基因多样性最高，CK处理次之，NPK处理最低。LUBSHUFF软件对narG基因群落组成的分析显示，施有机肥后含narG基因的细菌群落组成与CK之间有显著性差异（P<0.05），而化肥(NPK)没有产生显著影响。实验结果为进一步研究亚热带地区水稻土反硝化作用及反硝化功能菌提供了重要的依据。

CHEN

, YUAN

H C

, WU

J S

, WEI

W X

. Activity and composition of the denitrifying bacterial community respond differently to long-term fertilization
Acta Ecologica Sinica, 2009,29(11):5923-5929. (in Chinese)

URL [本文引用: 1]

DECKARD

E L

, BUSCH

R H

. Nitrate reductase assays as a prediction test for crosses and lines in spring wheat
Crop Science, 1978,18(2):289-293.

DOI:10.2135/cropsci1978.0011183X001800020024x URL [本文引用: 1]

[52]

黄懿梅, 安韶山, 曲东, 赵伟峰. 黄土丘陵区植被恢复过程中土壤酶活性的响应与演变
水土保持学报, 2007(1):152-155.

URL [本文引用: 1]

对宁夏南部丘陵区不同植被自然恢复阶段土壤脲酶、碱性磷酸酶、蔗糖酶、脱氢酶和过氧化氢酶活性的变化特征进行了研究。结果表明：土壤脲酶、碱性磷酸酶、蔗糖酶和脱氢酶基本上随着植被封育年限的增加而增大,过氧化氢酶活性对于植被恢复年限的响应不明显。植被封育的前23年中,土壤脲酶、碱性磷酸酶、蔗糖酶和脱氢酶的活性增加明显,23年后基本趋于稳定,增加不明显。封育78年的大针茅群落下的土壤脲酶和蔗糖酶（转化酶）活性最强,其土壤中碳素和氮素营养循环强度最大。脲酶与蔗糖酶、碱性磷酸酶和脱氢酶的活性极显著相关,表明土壤酶在促进土壤有机物转化中存在共性关系。这几种酶能够在一定程度上反映植被群落的演替和植被的恢复程度,自然封育对提高土壤生物学质量有重要的作用。

HUANG

Y M

, AN

S S

, QU

, ZHAO

W F

. Responses and evolution of soil enzymatic activities during process of vegetation recovering
Journal of Soil and Water Conservation, 2007(1):152-155. (in Chinese)

URL [本文引用: 1]

邹军, 喻理飞, 李媛媛. 退化喀斯特植被恢复过程中土壤酶活性特征研究
生态环境学报, 2010,19(4):894-898.

[本文引用: 1]

ZOU

, YU

L F

, LI

Y Y

. Study on soil enzyme activity characteristics during succession of degraded karst vegetation
Ecology and Environmental Sciences, 2010,19(4):894-898. (in Chinese)

[本文引用: 1]

[54]

邢肖毅, 黄懿梅, 黄海波, 安韶山, 刘栋. 黄土丘陵区子午岭不同植物群落下土壤氮素及相关酶活性的特征
生态学报, 2012,32(5):1403-1411.

DOI:10.5846/stxb201101090035 URL [本文引用: 1]

以黄土丘陵区子午岭林区裸露地为对照,选择撂荒地、白羊草草地、油松、山杨和辽东栎林地五种典型植被群落下0-10 cm和10-20 cm土层的土壤为研究对象,对土壤无机氮、有机氮、微生物量氮含量和脲酶、蛋白酶以及硝酸还原酶的活性进行了研究。结果表明,土壤中各种氮素基本表现为乔木林,尤其是辽东栎和油松下含量最高,而有机氮则在白羊草地富集明显。铵态氮为子午岭林区速效氮的主要形式。土壤铵态氮与微生物氮极显著正相关;有机氮和亚硝态氮、矿化氮、微生物氮均显著正相关。脲酶和硝酸还原酶活性在辽东栎群落下最高,蛋白酶在白羊草地下较高,且脲酶活性在土壤上层高于下层,而蛋白酶和硝酸还原酶并没有表现出明显规律。脲酶活性和铵态氮、有机氮含量显著正相关,与微生物量氮极显著正相关;硝酸还原酶活性与铵态氮含量显著正相关;蛋白酶活性和土壤各种氮素含量无相关性。

XING

X Y

, HUANG

Y M

, HUANG

H B

, AN

S S

, LIU

. Soil nitrogen and enzymes involved in nitrogen metabolism under different vegetation in Ziwuling mountain in the Loess Plateau, China
Acta Ecologica Sinica, 2012,32(5):1403-1411. (in Chinese)

DOI:10.5846/stxb201101090035 URL [本文引用: 1]

王常慧, 邢雪荣, 韩兴国. 草地生态系统中土壤氮素矿化影响因素的研究进展
应用生态学报, 2004(11):2184-2188.

URL [本文引用: 1]

The biological and non-biological factors affecting soil N availability in grassland ecosystems were reviewed in this paper.Nitrogen cycling in grassland ecosystems is one of the focuses widely concerned.Nitrogen mineralization is affected by many factors in grassland ecosystem,which can be classified into biological and non-biological ones.Biological factors include soil animals,soil microorganisms and plants.Soil animals could accelerate the organic matter to degrade.The species,structure and function of soil microorganisms correlate significantly with N degradation and mineralization.Different vegetation has different effects on soil nitrogen mineralization.The non-biological factors include environmental factors and anthropogenic disturbance,which have direct and obvious effects on N mineralization.The effects of soil temperature and moisture on N mineralization are given more attention,but many phenomena,such as the effects of soil type,soil structure and vegetation type on N mineralization still could not be explained clearly,and no general agreements were reached.Anthropogenic disturbance such as grazing,firing and fertilization influence N mineralization evidently.It is of great significance to understand the N cycling pattern and N availability in different grassland ecosystems all around the world.

WANG

C H

, XING

X R

, HAN

X G

. Advances in study of factors affecting soil N mineralization in grassland ecosystems
Chinese Journal of Applied Ecology, 2004(11):2184-2188. (in Chinese)

URL [本文引用: 1]

谢泽宇, 罗珠珠, 李玲玲, 蔡立群, 张仁陟, 牛伊宁, 赵靖静. 黄土高原不同粮草种植模式土壤碳氮及土壤酶活性
草业科学, 2017,34(11):2191-2199.

[本文引用: 1]

XIE

Z Y

, LUO

Z Z

, LI

L L

, CAI

L Q

, ZHANG

R Z

, NIU

Y N

, ZHAO

J J

. Soil carbon and nitrogen and soil enzyme activities of different forage planting models on the Loess Plateau
Pratacultural Science, 2017,34(11):2191-2199. (in Chinese)

[本文引用: 1]

[57]

ROS

G H

, HANEGRAAF

M C

, HOFFLAND

, RIEMSDIJK

W H V

. Predicting soil N mineralization: Relevance of organic matter fractions and soil properties
Soil Biology & Biochemistry, 2011,43(8):1714-1722.

DOI:10.1016/j.soilbio.2011.04.017 URL [本文引用: 1]

[58]

PRESCOTT

C E

, VESTERDAL

H N C

. Nitrogen turnover in forest floors of coastal douglas-fir at sites differing in soil nitrogen capital
Ecology, 2000,81(7):1878-1886.

DOI:10.1890/0012-9658(2000)081[1878:NTIFFO]2.0.CO;2 URL [本文引用: 1]