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The Characteristics of Soil Ammonia Volatilization Under Different Fertilizer Application Measures in Corn Field of Liaohe Plain

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【Objective】 This study was performed to explore the characteristics of ammonia (NH3) volatilization from corn field affected by different fertilization measures, to understand the contribution of different fertilization measures to NH3 emission, and to obtain the localized NH3 emission factors of chemical fertilizer application in Liaohe plain, northeastern China, so as to provide reference for relevant research in the fields of atmospheric environment and ecology. 【Method】 A field experiment of NH3 emission responses under different fertilization measures was carried out in the south experimental field of Shenyang agricultural university, Liaoning province from May to October 2018, which was set up with 5 treatments: no nitrogen treatment (T0), half-amount conventional fertilization (T1), conventional fertilization + biochar (T2), one-time conventional fertilization (T3), conventional fertilization (T4). The base fertilizer was coated with slow-release fertilizer and urea was applied at jointing stage. From May to October 2018, NH3 gas was collected by aeration method, ammonium concentration was analyzed by continuous flow analyzer, and NH3 emission flux was calculated. Meanwhile, ammonium nitrogen (NH4+-N) content in soil was measured. 【Result】 The NH3 volatilization rate showed a bimodal trend after the application of base fertilizer, and the maximum NH3 volatilization rates occurred on the 1st-2d or 5th-7d after the application of base fertilizer, respectively. The maximum NH3 volatilization rates in the treatments of base fertilizer were as follows: T1>T2>T3>T4>T0. All treatments reached the maximum NH3 volatilization rates at the 1st - 2d after applying top dressing, and the maximum NH3 volatilization rates at the top dressing stage were as follows: T4>T2>T1>T3>T0. The accumulation of NH3 volatilization loss was shown as T2)>T4>T3>T1>T0. There was no significant difference in soil NH4 +-N content between different treatments in different periods, but the soil NH4 +-N content and NH3 volatilization rate in the same period showed a similar change trend, and the correlations after applying top fertilizer were more significant than that after applying base fertilizer. Due to the application of urea under T1, T2 and T4 at top dressing period, urea released NH4+-N more rapidly than slow-release fertilizer, and NH3 volatilization was relatively fast. Overall, a 50% reduction in nitrogen application resulted in a 20% reduction in NH3 volatilization loss accumulation. The accumulation of NH3 volatilization loss was significantly different among the treatments during the growth season. T2 had the largest accumulation of NH3 volatilization loss. Under the same nitrogen application amount, the cumulative ammonia volatilization loss of biochar treatment increased by 22%. Under the condition of the same nitrogen application amount in the whole growth season, the NH3 volatilization accumulation was reduced by 12% in the one-time application of slow-release fertilizer without urea topdressing than that with urea topdressing. 【Conclusion】 Ammonia volatilization showed a marginal decreasing effect with the increase of nitrogen application. Biochar promoted ammonia volatilization in farmland, while corn straw biochar was alkaline, resulting in increased accumulation of ammonia volatilization. However, it had the characteristics of large porosity and specific surface area, strong adsorption effect, and could improve soil and reduce emissions of other greenhouse gases. The ammonia volatilization was significantly reduced by applying slow-release fertilizer at one time without urea topdressing.
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中国农业科学 2020,53(18):3741-3751
Scientia Agricultura Sinica doi: 10.3864/j.issn.0578-1752.2020.18.010
收稿日期:2019-11-05接受日期:2020-01-15
基金项目:国家重点研发计划(2017YFC0212301、国家自然科学基金(41575129
联系方式:赵欣周,E-mailxinzhou0229@163.com。通信作者谢立勇,E-mailxly0910@syau.edu.cn。通信作者赵洪亮,E-mailzhanghl1980@126.com
开放科学(资源服务)标识码(OSID):
辽河平原玉米田不同施肥下的土壤氨挥发特征
赵欣周 1,张世春 2,李颖 1,郑益1,赵洪亮 1,谢立勇 1
1沈阳农业大学农学院,沈阳 1101612中国科学院东北地理与农业生态研究所,长春 130102
摘要:【目的】通过不同施肥措施对氨气排放贡献的研究,获得辽河平原化肥施用本地化的氨排放因子,
为大气环境和生态等领域的相关研究提供参考借鉴。【方法】于 2018 5—10 月在沈阳农业大学试验基地开
展不同施肥措施下的氨气排放的大田试验,以基肥施树脂包衣缓释化肥、拔节期追施尿素为常规施肥方式,
置无氮处理(T0)、常规施肥减半(T1)、常规施肥+生物炭(T2)、常规施肥一次性施入(T3)、常规施肥
(T4)5 个处理。采用通气法在玉米全生育期内定时收集氨气,利用流动分析仪检测计算氨排放通量,同时测
定土壤铵态氮含量。【结果】施基肥后氨挥发速率呈现双峰趋势,各处理分别于施基肥后第 1—2 天或第 5—7
天达到氨挥发速率最大值,施基肥后各处理氨挥发速率最大值表现为:常规施肥减半(T1)>常规施肥+生物
炭(T2)>常规施肥一次性施入(T3)>常规施肥(T4)>无氮处理(T0);施追肥后各处理均于第 1—2
达到氨挥发速率最大值,追肥后各处理氨挥发速率最大值表现为:常规施肥(T4)>常规施肥+生物炭(T2)
>常规施肥减半(T1)>常规施肥一次性施入(T3)>无氮处理(T0)。氨挥发损失累积量表现为常规施肥+
生物炭(T2)>常规施肥(T4)>常规施肥一次性施入(T3)>常规施肥减半(T1)>无氮处理(T0)。各时
期各处理间的土壤铵态氮含量差异并不显著,但土壤铵态氮含量和同时期土壤氨挥发速率呈现出相似的变化趋
势,施追肥后两者的变化趋势比施基肥后更加相似。由于 T1、T2、T4 追肥期施尿素,尿素释放铵态氮比缓释
化肥更加迅速,同时氨挥发也相对较快。整体来看,减少 50%施氮量,氨挥发损失累积量只减少 20%。各处理
间生长季内氨挥发损失累积量差异显著,常规施肥+生物炭(T2)的氨挥发损失累积量最多,在施氮量相同的
情况下,加施生物炭氨挥发损失累积量增加 22%。全生长季施氮量相同的情况下,一次性施入缓释化肥而不采
取尿素追肥的措施比以尿素作为追肥的措施的氨挥发累积量减少 12%。【结论】氨挥发随着施氮量增加呈现边
际递减效应。生物炭促进了农田氨挥发,玉米秸秆生物炭呈碱性,导致了氨挥发累积量的增加,但其具有孔隙
度和比表面积大、吸附效果强的特点,可改良土壤和减少其他温室气体。一次性施入缓释化肥而不采取尿素追
肥显著降低了氨挥发。
关键词:氨排放因子;氨挥发速率;生物炭;施肥;玉米;辽河平原
The Characteristics of Soil Ammonia Volatilization Under Different
Fertilizer Application Measures in Corn Field of Liaohe Plain
ZHAO XinZhou1, ZHANG ShiChun2, LI Ying1, ZHENG YiMin1, ZHAO HongLiang1, XIE LiYong1
(1 College of Agriculture, Shenyang Agricultural University, Shenyang 110161; 2 Institute of Northeast Geography and Agricultural
Ecology, Chinese Academy of Sciences, Changchun 130102)
Abstract: ObjectiveThis study was performed to explore the characteristics of ammonia (NH3) volatilization from corn
field affected by different fertilization measures, to understand the contribution of different fertilization measures to NH3
3742 53
emission, and to obtain the localized NH3 emission factors of chemical fertilizer application in Liaohe plain, northeastern China,
so as to provide reference for relevant research in the fields of atmospheric environment and ecology. Method A field
experiment of NH3 emission responses under different fertilization measures was carried out in the south experimental field of
Shenyang agricultural university, Liaoning province from May to October 2018, which was set up with 5 treatments: no nitrogen
treatment (T0), half-amount conventional fertilization (T1), conventional fertilization + biochar (T2), one-time conventional
fertilization (T3), conventional fertilization (T4). The base fertilizer was coated with slow-release fertilizer and urea was applied
at jointing stage. From May to October 2018, NH3 gas was collected by aeration method, ammonium concentration was
analyzed by continuous flow analyzer, and NH3 emission flux was calculated. Meanwhile, ammonium nitrogen (NH4+-N)
content in soil was measured. Result The NH3 volatilization rate showed a bimodal trend after the application of base
fertilizer, and the maximum NH3 volatilization rates occurred on the 1st-2d or 5th-7d after the application of base fertilizer,
respectively. The maximum NH3 volatilization rates in the treatments of base fertilizer were as follows: T1T2T3T4T0.
All treatments reached the maximum NH3 volatilization rates at the 1st - 2d after applying top dressing, and the maximum NH3
volatilization rates at the top dressing stage were as follows: T4T2T1T3T0. The accumulation of NH3 volatilization
loss was shown as T2)T4T3T1T0. There was no significant difference in soil NH4+-N content between different
treatments in different periods, but the soil NH4+-N content and NH3 volatilization rate in the same period showed a similar
change trend, and the correlations after applying top fertilizer were more significant than that after applying base fertilizer. Due
to the application of urea under T1, T2 and T4 at top dressing period, urea released NH4+-N more rapidly than slow-release
fertilizer, and NH3 volatilization was relatively fast. Overall, a 50% reduction in nitrogen application resulted in a 20%
reduction in NH3 volatilization loss accumulation. The accumulation of NH3 volatilization loss was significantly different
among the treatments during the growth season. T2 had the largest accumulation of NH3 volatilization loss. Under the same
nitrogen application amount, the cumulative ammonia volatilization loss of biochar treatment increased by 22%. Under the
condition of the same nitrogen application amount in the whole growth season, the NH3 volatilization accumulation was reduced
by 12% in the one-time application of slow-release fertilizer without urea topdressing than that with urea topdressing.
ConclusionAmmonia volatilization showed a marginal decreasing effect with the increase of nitrogen application. Biochar
promoted ammonia volatilization in farmland, while corn straw biochar was alkaline, resulting in increased accumulation of
ammonia volatilization. However, it had the characteristics of large porosity and specific surface area, strong adsorption effect,
and could improve soil and reduce emissions of other greenhouse gases. The ammonia volatilization was significantly reduced
by applying slow-release fertilizer at one time without urea topdressing.
Key words: ammonia emission factor; biochar; fertilizer application; ammonia volatilization rate; corn; Liaohe plain
0 引言
【研究意义】化肥在全球逐渐普及极大促进了农
业发展。然而,近年来化肥过量施用已造成土壤和水
体的环境污染[1]而农田化肥施用导致温室气体CO2
N2ONH3等)排放也成为全球气候变暖的原因之一[2]
其中化肥施入农田后所排入大气中的氨(NH3)可与
硫酸、硝酸等酸性气体成分反应生成二次无机气溶胶
SIA,主 (NH4)2SO4NH4NO3NH4Cl 等)
[3]
从而影响空气质量、能见度和人类健康。此外,不合
理的施肥也可导致农业氮肥利用率偏低,例如近年来
玉米氮肥表观利用率仅为 29.1%[4]。鉴于氨在大气环
境、生态和农业生产方面的重要性,对其排放、沉降
及其转化机制的研究已成为当前环境和生态领域的
研究热点之一。【前人研究进展】近年来我国学者主
要参考借鉴国外的氨排放因子,对各区域及全国的氨
排放量进行了大致估算,并对相关影响因素进行了分
[5-6],例如关于长三角氨排放清单的研究[7-8],关于
珠三角氨排放清单的研究[9],以及关于全国和其他地
区氨排放趋势的研究[10-12]。但由于我国区域差异大,
目前仍缺乏足够的代表各典型区域的本地化氨排放数
据。肥料对农田土壤氨挥发的影响比较复杂,近年
来各类化肥和生物炭影响土壤氨挥发的研究越来越
多。不同程度老化的生物炭对土壤氨挥发产生不同
的影响,例如高温裂解制备的新鲜玉米秸秆生物炭,
在经过冻融循环或高温裂解老化后添加至农田土壤
中,可使氨挥发累积量减少 30%,而添加自然老化
或新鲜玉米秸秆生物炭和玉米秸秆粉末的氨挥发累
积量只减少 19%—23%[13]。不同种类生物炭对不同
作物不同土壤类型氨挥发产生不同的影响,例如在
施氮 450 kg N·hm-2 的情况下,棉花秸秆生物炭还田减
少滴灌棉田氨挥发 40.59%[14]生物炭添加对稻田氨挥
18 赵欣周等:辽河平原玉米田不同施肥下的土壤氨挥发特征 3743
发损失有明显的促进效应,且具有阶段性特征,氨挥
发总量增加 69%[15];盐渍化土壤的情况下,常规施
+生物炭有效抑制了氨挥发,添加生物炭对滴灌和
漫灌氨挥发累积损失量分别降低了 57%44%[16]
可见各种施肥和生物炭影响不同作物的土壤氨挥发
有着比较明显的差异性。【本研究切入点】东北平
原是我国面积最大的平原,属于世界三大黑土区之
一,是中国主要的粮食产区。农田化肥的大量施用
是当地大气氨的重要排放源。但目前关于东北地区
氨排放因子的试验研究仍较为匮乏,更缺少详细地
针对该区域的本地化氨排放清单。【拟解决的关键
问题】本研究通过辽河平原地区农田试验,分析不
同施肥措施影响农田氨挥发的时间特征,获得沈阳
地区化肥施用本地化氨排放因子,以供大气环境和
生态等领域的相关研究参考借鉴。
1 材料与方法
1.1 试验场概况
试验地位于沈阳农业大学试验基地(41°82’N
123°56’E),属于温带半湿润大陆性季风气候,平均
海拔为 50 m,地势平坦,年均降雨量为 608 mm,年
均气温 8.0℃,年均最高气温 13.0℃,年均最低气温
3.0℃。昼夜及季节气温温差较大,四季分明。试验地
土壤为棕壤,020 cm 土层基本性状为:有机质含量
18.3 g·kg-1pH 6.9,碱解氮 90.6 mg·kg-1,全氮 0.8
g·kg-1,速效磷 151.0 mg·kg-1,速效钾 123.6 mg·kg-1
1.2 试验材料
供试的作物为春玉米(品种:东单 1331)。肥料
为当地生产普遍采用的树脂包衣缓释化肥N:P:K
30:10:12)、尿素(含氮 46%)和玉米秸秆生物炭
(缺氧条件下 450℃高温制备而成,pH 9.6,含碳量
40%)。
1.3 试验设计
以基肥施树脂包衣缓释化肥、拔节期追施尿素为
常规施肥方式,共设置 5个处理:T0(无氮处理)
不施任何肥料;②T1(常规施肥减半),基肥施入半
量缓释包衣化肥,拔节期追施半量尿素;T2(常规
施肥+生物炭),基肥施缓释包衣化肥,覆盖 3 000
kg·hm-2 生物炭,拔节期追施尿素;④T3(常规施肥一
次性施入),不追肥,一次性基施缓释包衣化肥;⑤
T4(常规施肥),基肥施缓释包衣化肥,拔节期追施
尿素。小区面积 6 m×10.3 m=61.8 m2随机区组排列,
每个处理设置 3次重复, 18 个小区。各处理施氮水
平见表 1
1 各处理施氮水平
Table 1 Nitrogen application level of each treatment
基肥量
Basal fertilizer quantity (kg N·hm-2)
处理
Treatment
N P2O5 K
2O
基肥种类
Basal fertilizer
type
追肥量
Top dressing
quantity (kg N·hm-2)
追肥种类
Top dressing
type
生育期施氮总量
Total nitrogen
application (kg N·hm-2)
生物炭施用量
Biochar application
(kg·hm-2)
T0 0 0 0 - - - 0 0
T1 45 15 18 SRF1) 45 尿素 Urea 90 0
T2 90 30 36 SRF 90 尿素 Urea 180 3000
T3 180 60 72 SRF - - 180 0
T4 90 30 36 SRF 90 尿素 Urea 180 0
1)SRF 为树脂包衣缓释化肥 1)SRF is resin coated sustained release fertilizer
本试验于 2018 年开展,播种日期为 510 日,
追肥日期为 75日。播种的同时施用基肥,基肥和
追肥均采用穴施方式。
1.4 样品采集与分析
施肥后土壤氨挥发量的测量:采用目前使用较多
的通气法[17]进行采样。该法准确度高,操作简便易行,
适合进行小区控制试验。将两块厚度为 2 cm、直 16
cm 的海绵均匀浸以 15 mL 的磷酸甘油溶液,置于内
15 cm、高 12 cm 的聚乙烯硬质塑料管中,下层海
绵距土壤表面 5 cm上层海绵与管顶相平,将聚乙烯
硬质塑料管随机分别放置于每个小区;24 h 后将下层
海绵取出,迅速装入密封袋中,同时换上另一块刚浸
过磷酸甘油溶液的海绵,上层海绵视干湿情况 37 d
更换一次;将换下的海绵带回实验室,放入 500 mL
广口塑料瓶中;向塑料瓶中加 300 mL KCl 溶液(1
mol·L-1),使海绵完全浸入其中,将塑料瓶封口后振
3744 53
1 h,而后取出静置,吸取一定量清液,于 24 h
用流动分析仪(AA3)氨模块(MT7)进行分析。
氨挥发速率(Fi, g N·hm-2·d-1)、生长季内氨挥发
损失累积量(Fcum, kg N·hm-2)分别计算为:
99.0
10000
××
×
=
i
i
iDS
A
F
=
+
+×
+
=1
1
1
1)(
2
n
i
ii
ii
cum tt
FF
F
式中,Ai为第 i次采样收集到的 NH3量(g N),
Di为第 i次采样的收集时间(d),SNH3收集装
置的有效横截面积(m2),ti+1ti为两个相邻测定
日期的间隔(d[18]0.99 为该收集装置的 NH3
收率[17]
在土壤氨挥发量采样的同时,对土壤铵态氮含量
进行采样分析。采用 5点取土法采样。每小区每次取
5个采样点,分别于 10 cm 土层处取 20 g 鲜土,将
浸入 200 mL KCl 溶液(1 mol·L-1),振荡 1 h,待悬
浊液澄清后,吸取一定量上层清液,于 24 h 内用流动
分析仪进行分析。
土壤氨挥发和土壤铵态氮含量的取样分别在施基
肥和追肥后第 12357101520 天进行一
次,其余时期每 10 天取样一次。
1.5 数据统计分析
利用 Microsoft Office Excel 2016 IBM SPSS
Statistics 22 软件进行数据处理、相关性分析和显著性
分析。
2 结果
2.1 不同施肥措施对土壤氨挥发速率的影响
如图 1所示,施基肥后氨挥发速率呈现双峰趋势,
各处理在分别于施肥后 1—2 d 5—7 d 达到氨挥发
速率最大值。施用基肥后 1 d T1 就达到了最大单日
排放量,为 113.67 g N·hm-2·d-1,其余处理排放量不明
显;第 2 T1 排放量急剧降为 59.31 g N·hm-2·d-1
T3 排放量突增一倍, 95.77 g N·hm-2·d-1 3 T3
下降至 40.50 g N·hm-2·d-1T1 继续呈下降趋势; 3 d
T2 排放量呈逐渐增大态势,分别排放 66.7882.71
88.98 g N·hm-2·d-1;第 5 T2 排放量为 112.72 g
N·hm-2·d-1 达到峰值,其他各处理排放量均有上升;到
7天时 T1 排放量达 82.59 g N·hm-2·d-1T3 回升至
98.57 g N·hm-2·d-1 且达到该处理峰值,T4 91.11 g
N·hm-2 达到该处理峰值,T2 仍排放 108.16 g
N·hm-2·d-1;第 10 各处理均急剧下降,第 15
处理出现回升,随后缓慢下降;至第 40 天,各处理排
放量降至 45—61 g N·hm-2·d-1 范围内。
玉米生长季第 56 天各处理施用追肥。施入追肥
后第 1天,各处理(除 T3 外)氨挥发速率均达到追
肥期最大,其中 T1 254.16 g N·hm-2·d-1T2
412.41 g N·hm-2·d-1T4 447.58 g N·hm-2·d-1T4
日排放量为 T1 1.8 倍,为 T3 6倍,T2 T4
相似表现,二者仅差 8.5%。第 2T3 氨挥发速率达
到最大值 79.92 g N·hm-2·d-1,随后各处理氨挥发速率
急剧下降,并保持轻微波动。直至第 15 天,T2 当日
氨挥发速率骤升至 140.67 g N·hm-2·d-1随后下降。第
20 天和第 50 天各处理当日氨挥发速率极其微弱。施
追肥后各处理氨挥发速率如图 2所示。
整体而言,T4 T2 氨挥发速率较高,T1 T3
氨挥发速率较小。施入追肥后氨挥发更加迅速。施基
肥后各处理氨挥发速率最大值表现为:常规施肥减半
T1)>常规施肥+生物炭(T2)>常规施肥一次性
150
100
50
0
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123571015203040
施基肥后天数 Days after basal fertilization (d)
氨挥发速率
NH3volatilization (g N·hm-2·d-1)
T0 T1 T2 T3 T4
1 施基肥后各处理氨挥发速率
Fig. 1 Ammonia volatilization rate after basal fertilizer application
18 赵欣周等:辽河平原玉米田不同施肥下的土壤氨挥发特征 3745
600
400
200
0
500
300
100
12357101520304050
T0 T1 T2 T3 T4
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施基肥后天数 Days after basal fertilization (d)
氨挥发速率
NH3volatilization (g N·hm-2·d-1)
2 施追肥后各处理氨挥发速率
Fig. 2 Ammonia volatilization rate after top dressing
施入(T3>常规施肥(T4>无氮处理(T0);施
追肥后各处理氨挥发速率最大值表现为:常规施肥
T4>常规施肥+生物炭T2>常规施肥减半T1
>常规施肥一次性施入(T3)>无氮处理(T0)。
2.2 不同施肥措施对氨挥发损失累积量的影响
施基肥后 40 d T3 T2 氨挥发损失累积量较其
他处理大,分别为 2.843.03 kg N·hm-2,而 T4T1
分别为 2.562.2 kg N·hm-2。氨挥发损失累积量对比:
常规施肥+生物炭T2)>常规施肥一次性施入T3
>常规施肥(T4>常规施肥减半T1)>无氮处理
T0施追肥后 50 dT1 氨挥发损失累积量为 1.94
kg N·hm-2T2 3.16 kg N·hm-2T3 1.71 kg N·hm-2
T4 2.52 kg N·hm-2,氨挥发损失累积量大小对比:
常规施肥+生物炭(T2)>常规施肥(T4)>常规施
肥减半(T1>常规施肥一次性施入T3)>无氮处
理(T0)。常规施肥一次性施入T3)处理由于没有
追肥,所以后期排放不明显。各处理的氨挥发损失累
积量如图 3所示。
整个生长季内氨挥发损失累积量表现为:常规施
+生物炭(T2)>常规施肥(T4)>常规施肥减半
T1>常规施肥一次性施入T3>无氮处理T0
各处理氨挥发损失率表现为:常规施肥+生物炭T2
>常规施肥减半(T1>常规施肥T4)>常规施肥
一次性施入(T3)。与施入缓释化肥最多的 T3 相比,
总施氮量相同的 T2 T4 氨挥发损失累积量分别增加
35.7%15.6%与施入生物炭的 T2 相比,总施氮
量相同的 T4 氨排放损失累积量降低了 17.8%。虽然
T4 基肥和追肥施氮量为 T1 2倍,但 T4 氨挥发损
失累积量却仅为 T1 氨挥发损失累积量的 1.22 倍。土
壤氨挥发损失率和氨挥发损失率如表 3所示。
T0 T1 T2 T3 T4
4
3
2
1
0
氨挥发损失累积量
NH3accumulation (kg N·hm-2)
施追肥后 After top dressing
施基肥后 After basal fertilization
dd
c
c
a
aab
cd
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3 各处理氨挥发损失累积量
Fig. 3 Cumulative ammonia volatilization loss of each treatment
3746 53
2 土壤氨挥发损失累积量和氨挥发损失率
Table 2 Soil ammonia volatilization loss accumulation and
ammonia volatilization loss rate
处理
Treatment
氨挥发损失累积量
NH3 accumulation
(kg N·hm-2)
氨挥发损失率
Loss
(%)
T0 3.12±0.10e
T1 4.14±0.09d 1.13±0.21b
T3 4.56±0.08c 0.80±0.06c
T4 5.09±0.03b 1.09±0.15b
T2 6.19±0.17a 1.70±0.03a
2.3 不同施肥措施下土壤铵态氮含量与氨挥发速率
的关系
不同施肥措施下的土壤铵态氮含量变化特征如
4所示。施入基肥后第 1 各处理土壤铵态氮
含量显现为生长季较高水平,其中 T1 T2 达到施
基肥后最高水平,分别为 22.226.5 kg N·hm-2,随
后第 2 各处理土壤铵态氮含量急剧下降,此处可
能与降水有关。 5天各处理土壤铵态氮含量回升,
其中 T4 达到最高水平,为 16.8 kg N·hm-2,第 7
各处理回落至较低水平。 10 天后各处理土壤铵态
氮含量开始升高,15 天时 T3 T4 土壤铵态氮含
量达到最高水平,分别为 19.518.1 kg N·hm-2,此
时各处理土壤铵态氮含量表现为:常规施肥一次性
施入T3>常规施肥T4>常规施肥+生物炭T2
>常规施肥减半(T1)>无氮处理(T0),此高水
平态势波动保持至第 30 天,第 40 天各处理下降至
较低水平。
施入追肥后第 1 T1T4 土壤铵态氮含量达到
生长季最高水平,分别为:23.324.6 kg N·hm-2。随
10 d 土壤铵态氮含量下降,直至第 10 天各处理土壤铵
态氮含量升到了较高水平,其中 T4 17.0 kg N·hm-2
T0 同一天的 1.64 倍,此时各处理土壤铵态氮含量
表现为:常规施肥(T4)>常规施肥+生物炭(T2
123571015203040
施基肥后天数 Days after basal fertilization (d)
30
20
10
0
25
15
5
35
40 T0 T1 T2 T3 T4
铵态氮含量
NH4+-N content (kg N·hm-2)
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123571015304050
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20
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5
铵态氮含量
NH4+-N content (kg N·hm-2)
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4 不同施肥措施下的土壤铵态氮含量变化特征
Fig. 4 Variation characteristics of ammonium nitrogen content in soil under different fertilization measures
18 赵欣周等:辽河平原玉米田不同施肥下的土壤氨挥发特征 3747
>常规施肥减半(T1)>常规施肥一次性施入(T3
>无氮处理(T0),与施入追肥量排序一致。第 15
天后,各处理土壤铵态氮含量下降。
整体而言,基肥期土壤铵态氮含量峰值出现的时
间靠后,其中有 3个处理峰值出现在第 15 天,而追肥
期土壤铵态氮含量峰值出现的时间均为第 1天。根据
显著性分析,各处理间的土壤铵态氮含量差异并不显
著。无氮处理(T0)仍有较高的土壤铵态氮含量,这
可能与生长季雨水多且无氮处理(T0小区大多处于
农田排水口有关。
如图 5所示,T1T2T3T4 的土壤铵态氮含
量和同时期土壤氨挥发速率呈现出相似的变化趋势,
15
10
5
0
90
60
30
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12
4
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30
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0
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30
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20
5
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10
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0 10 20 30 40 0 10 20 30 5040
0 10 20 30 40 0 10 20 30 5040
0 10 20 30 40 0 10 20 30 5040
0 10 20 30 40 0 10 20 30 5040
0 10 20 30 40 0 10 20 30 5040
T0 T0
T1 T1
T2 T2
T3 T3
T4 T4
施基肥后天数 Days after basal fertilization 施追肥后天数 Days after top dressing
土壤铵根离子含量 NH4+content 土壤氨挥发速率 NH3volatilization
5 不同施肥措施下土壤铵态氮含量与土壤氨挥发速率时间变化
Fig. 5 Time variation diagram of soil ammonium nitrogen content and soil ammonia volatilization rate under different fertilization measures
3748 53
施追肥后两者的变化趋势比施基肥后更加相似。如表
3所示,对土壤铵态氮含量和土壤氨挥发速率之间采
Pearson 相关性分析。结果显示基肥期各处理的土
壤铵态氮和土壤氨挥发速率之间相关性弱或相关不显
著。施追肥后 T1T4 的土壤铵态氮含量和土壤氨挥
发速率之间为极强正相关、T2 施追肥后两者为强正相
关,结果均为显著。
3 不同施肥措施下土壤氨挥发速率与土壤铵态氮含量
Pearson 相关性分析
Table 3 Pearson correlation analysis of soil ammonia volatilization
rate and soil ammonium nitrogen content under
different fertilization measures
时期 Stage 处理 Treatment r r value P P value
T0 -0.076 0.05
T1 0.573 0.05
T2 -0.105 0.05
T3 -0.228 0.05
施基肥后
After basal
fertilization
T4 0.353 0.05
T0 0.614 0.05
T1 0.810** 0.01
T2 0.757* 0.05
T3 0.437 0.05
施追肥后
After top
dressing
T4 0.803** 0.01
**表示极强相关;*表示强相关
** Indicates extreme correlation; * Indicates strong correlation
3 讨论
本研究基于当前东北地区普遍采用的农田施肥
措施,观测玉米施入基肥期后 40 d 和施入追肥后
50 d 的土壤氨挥发速率及土壤铵态氮含量,探讨了
不同施肥措施影响农田氨挥发的时间特征。本试验
中,追肥初期比基肥初期氨挥发更为明显,可能的
原因是基肥施用缓释包衣化肥,追肥除常规施肥一
次性施入(T3处理外皆用尿素,而尿素的氨挥发
损失率比缓释包衣化肥更高。施基肥和追肥后土壤
铵态氮峰值出现时间的差异说明尿素比缓释肥料
释放铵态氮更加迅速。相比于缓释化肥,施用尿素
使得土壤铵态氮含量和土壤氨挥发速率之间呈现
强正相关,这说明尿素在迅速释放铵态氮的时候,
也在迅速增加氨挥发,而缓释化肥释放铵态氮则更
加稳定[19-20]
本研究得出的结论为生物炭促进氨挥发[21]。生
物炭对氨排放的促进作用可能主要是由于水和土壤
pH NH4+-N 浓度的增加导致的[22]。对比前人
研究采用生物炭肥料(经包覆酸化生物炭的尿素颗
粒)显著降低了氨挥发[23]本研究所用玉米秸秆生
物炭 pH 9.6呈碱性,反而导致氨挥发累积量的
增加。另外,老化生物炭相较于新鲜生物炭 pH
偏中性[24-25]可相对降低 NH3排放量,避免有效氮的
积累,可用于改良土壤[26]。玉米秸秆生物炭具有孔隙
度和比表面积大、吸附效果强、碱性强的特点[27-28]
虽然其促进了 NH3排放,但施用生物炭同时降低了
温室气体强度GHGI)和 CO2排放量[29-30],并
降低了 N2O排放量[31]。此外,不同类型生物炭影响
不同农田 NH3排放的内在机制研究还不完善,今后
有待深入。
土壤氨挥发研究是构建精准的农业氨排放清单
的重要基础。本研究采用通气法取样和流动分析仪
测量了不同化肥施用措施下的土壤氨排放速率和排
放通量,补充了东北地区本地化农田化肥施用氨排
放因子数据。与其他的氨排放研究相比[32-34],本研
究中获得的氨排放因子数值较小,其原因可能包括:
1)基肥期所采用的缓释化肥可显著减少氨挥发,
各类研究表明各类缓释化肥(包括树脂包衣)的氨
挥发累积量与尿素相比下降幅度介于 21.7%
64.6%[35-39]2在氨挥发试验的 106 d 中, 34 d
降雨,且在施肥后较集中,过多呈酸性的降水可能
导致氨挥发减少。因此当地施肥种类、方式等农业
耕作习惯以及各地区土壤、气候等自然特征可能导
致了土壤氨挥发的显著地区差异性。今后仍需要加
强开展典型区域的氨挥发研究,获得其时间、空间
特征和影响因素,从而为完善构建精准的东北地区
农田化肥施用本地化氨排放清单提供理论和数据
支撑。
4 结论
氨挥发随着施氮量增加呈现边际递减效应。在本
研究中减少 50%施氮量,氨挥发损失累积量只减少
20%。生物炭促进了玉米农田氨挥发。在施氮量
相同的情况下,加施碱性生物炭氨挥发损失累积量
增加 22%。一次性施入缓释化肥而不采取尿素追肥
显著降低了氨挥发。全生长季施氮量相同的情况下,
一次性施入缓释化肥而不采取尿素追肥的措施比以
尿素作为追肥的措施的氨挥发累积量减少 12%。与
18 赵欣周等:辽河平原玉米田不同施肥下的土壤氨挥发特征 3749
缓释化肥相比,尿素释放铵态氮更加迅速,同时氨
挥发也相对较快。
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(责任编辑 李云霞)
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Article
Full-text available
The characteristics of ammonia volatilization and nitrous oxide emission from a paddy soil were examined under 9-year application of different slow/controlled release urea with the common large granule urea (U) as the control. The results showed that compared with the control, all slow/controlled release urea treatments, except 25.8% increase of ammonia volatilization under 1% 3,4-dimethylpyrazole phosphate (DMPP)+U, could decrease the ammonia volatilization. Polymer coated urea (PCU) dominated the highest reduction of 73.4% compared to U, followed by sulfur coated urea (SCU) (72.2%), 0.5% N-(N-butyl) thiophosphoric triamide (NBPT)+1% DMPP+U (71.9%), 1% hydroquinone (HQ)+3% dicyandiamide (DCD)+U (46.9%), 0.5% NBPT+U (43.2%), 1% HQ +U (40.2%), 3% DCD+U (25.5%), and the ammonia volatilization under different slow/controlled release urea treatments were statistically lower than that of U (P<0.05). 1% DMPP+U caused the lowest emission of N2O under different slow/controlled release urea treatments. The slow/controlled release urea also had a significant potential of N2O emission reduction: 1% DMPP+U showed the highest eduction of 74.9% compared to U, followed by PCU (62.1%), 1% HQ+3% DCD+U (54.7%), 0.5% NBPT+1% DMPP+U (42.2%), 3% DCD+U (35.9%), 1% HQ +U (28.9%), 0.5% NBPT+U (17.7%), SCU (14.5%), and N2O emissions under different slow/controlled release urea treatments were statistically lower than that of U (P<0.05). The comprehensive analysis showed that 0.5% NBPT+1% DMPP+U, SCU and PCU had similar effects on decreasing the ammonia volatilization and N2O emission and were remarkably better than the other treatments. The slow release urea with the combination of urease and nitrification inhibitors should be the first choice for reducing N loss and environmental pollution in paddy field, in view of the higher costs of coated urea fertilizers.
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For a long time there has been excessive use of synthetic fertilisers applied to the decreasing area of arable land to help meet increasing food demand, which causes NH3 volatilization and land degradation. In this study, we conducted a nationwide inventory of NH3 emissions from synthetic nitrogen fertilizers in China from 1991 to 2013. We estimated that NH3 emissions increased from 3.20 to 5.21 Tg NH3 yr‐1. Due to different agricultural practices, fertilizer use schedules and ambient temperature, monthly NH3 emissions have varied greatly. NH3 emissions during the spring and summer accounted for approximately 83% of the national total in 1991, 1998, 2005, and 2013. Similarly, the spatial distribution of NH3 emissions exhibited large heterogeneity in 1991, 1998, 2005, and 2013. High emissions occurred in the eastern and central provinces as well as eastern Sichuan. Based on NH3 emissions in Chinese counties for 1991–1998, 1999–2005 and 2006–2013, the Pearson correlation coefficient was applied to compute the changing trends in NH3 emissions and fertilization rates. The results showed that the NH3 emissions from the major grain‐producing regions increased, while those from the eastern provinces, which experienced rapid economic development, decreased. In addition, fertilizer amount, arable land area, grain yield and primary industry have been shown to be largely correlated to NH3 emissions based on principal component analysis (PCA). Therefore, the results of this study have significant implications for improving the efficient use of fertilizers and preventing soil and/or land degradation.
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As the primary rice-producing country in the world, China has applied increasing amounts of synthetic fertilizers on rice fields, which has a large impact on environmental pollution and human health. In this study, a comprehensive inventory of fertilizer application to rice fields was compiled for China from 1979–2015. In 2015, fertilizer application was estimated to be 0.96 × 10⁹ kg for early rice, 2.67 × 10⁹ kg for single rice, and 1.11 × 10⁹ kg for late rice. Based on the fertilizer application and region-specific emissions factors, ammonia (NH3) volatilizations from growing-season rice fields were estimated over the same period. We found that the total NH3 emissions increased during 1979–1998, while decreased during 1998–2015 with fluctuations. The decreasing trend of NH3 emission was likely attributed to changes of application proportions of ammonium bicarbonate (ABC) and other fertilizers. ABC and urea were the two dominant contributors, and contributed over 90% of the total NH3 emissions. Spatially, high emissions were identified in the Middle-lower Yangtze River Plain, Huaihe River Basin, Taihu Lake region, Pearl River delta and Sichuan basin. Monthly emissions patterns were estimated according to rice calendars. The damage from NH3 emissions was estimated as 26.79 billion yuan and accounted for 0.04% of the Gross Domestic Production of China in 2015. Finally, we discussed the NH3 reduction strategies from the perspective of both the government and farmers and suggested that an incentive scheme should be established to guide farmers to optimize traditional agricultural management.
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China is the world’s largest emitter of gaseous ammonia (NH3), a compound that poses severe risks to human and ecosystem health. Adding biochar and inhibitors to soils has been suggested as a method to increase carbon sequestration and reduce nitrous oxide emissions, however, the effects of the amendments on NH3 emissions are poorly understood. We conducted a field experiment to evaluate the effect of applying biochar combined with a urease inhibitor (hydroquinone, HQ) and a nitrification inhibitor (dicyandiamide, DCD) on NH3 emissions, rice yields, and N use efficiency (NUE) during two growth seasons. Four replicates of seven treatments comprising no urea fertilizer (control), urea (N), biochar (B), urea+biochar (NB), NB+urease inhibitor (NBUI), NB+nitrification inhibitor (NBNI), and NB+urease and nitrification inhibitors (double inhibitor) (NBDI), were arranged in a randomized complete block design. Wheat straw biochar was applied once, in June 2014. Biochar in the NB treatment increased NH3 losses by 14.1% in the first rice season (P < 0.05), primarily due to increased pH and concentrations of NH4 +-N in the floodwater, and decreased NH3 losses in the second rice growth season by 6.8%, probably due to its high adsorption capacity for NH4 + and increased nitrification. The combined application of biochar and DCD increased NH3 losses by 47.0% and 17.2% in 2014 and 2015, respectively. The application of biochar+double inhibitors was shown to have no effect on NH3 losses in the first rice growth season, but in the second year, NH3 losses were reduced by 19.8% (P < 0.05). The combination of biochar and HQ decreased NH3 losses by 10.5–23.4% during the two growth seasons (P < 0.05) and the addition of biochar either alone (NB), or in combination with HQ (NBUI) or double inhibitors (NBDI), increased rice yield by 7.4–16.5% and NUE from 29.4% in the N treatment (N) to 42.5%. The combined application of biochar and DCD did not have an effect on rice yield and NUE in the first year, but increased yield and NUE in the second year (P < 0.05). Overall, our results suggest that the combination of biochar and HQ or the combined application of urease and nitrification inhibitors to soil enriched with biochar at least one year previously could be an effective practice for reducing NH3 emissions and increasing rice yields.