华北山前平原农田氨挥发速率与调控研究

本文依托中国科学院栾城农业生态系统试验站小麦-玉米轮作长期田间试验, 利用双层海绵氨吸收装置, 分析了不同施肥处理下氨挥发速率和损失量的变化规律; 并采用室内培养试验方法, 分析了浇水和秸秆还田等不同措施下氨挥发变化特征。结果表明, 肥料施用时间、土壤温度和灌水等因素显著影响土壤氨挥发速率; 氨挥发损失量在0.66~35.00 kg·hm^-2·d^-1 之间, 占施肥量的0.09%~14.90%, 且大部分氨挥发发生在夏玉米时期。施肥后及时浇水能有效减少氨挥发, 特别是在低初始水分条件下最为明显; 而在高土壤水分含量条件下, 浇水时间对氨挥发量的影响减弱。与单施化肥相比, 小麦或玉米秸秆混合配施化肥增加了石灰性土壤的尿素水解速率, 缩短了尿素的氨挥发时间, 并可显著减少氨挥发损失。单施尿素的累积氨挥发损失量占尿素施用量的7.2%~9.7%, 而小麦或玉米秸秆配施尿素的累积氨挥发损失量分别占尿素施用量的1.1%~2.1% 和2.2%~7.2%。因此, 为了减少农田氨挥发损失, 在施用尿素时应充分考虑土壤水分状况和秸秆类型对氨挥发的影响。     

脲酶抑制剂与硝化抑制剂对稻田氨挥发的影响

采用密闭室间歇通气法和15N标记技术研究了尿素施入稻田后氨挥发损失特征以及脲酶抑制剂(N-丁基硫代磷酰三胺,NBPT)和硝化抑制剂(3, 4-二甲基吡唑磷酸盐,DMPP)对稻田氨挥发损失的影响。结果表明,稻田施用尿素后第4天氨挥发速率达到峰值,氨挥发损失主要发生在施肥后21天内。与单施尿素处理相比,添加NBPT处理的氨挥发速率峰值降低27.04%,累积氨挥发损失量降低21.65%;NBPT与DMPP配施时,氨挥发速率峰值降低12.95%,累积氨挥发损失量降低13.58%;而添加DMPP时,氨挥发速率峰值增加23.61%,累积氨挥发损失量与单施尿素的差异不显著。相关性分析表明,地表水中铵态氮浓度和pH值与氨挥发速率均达极显著正相关,说明二者是影响氨挥发速率的主要因素,而气温、 地温和水温与氨挥发速率的相关性不显著。与单施尿素相比,添加脲酶抑制剂可显著增加稻谷产量。脲酶抑制剂与硝化抑制剂配合施用可更有效地提高氮肥的回收率。综合降低氨挥发、 提高水稻产量及地上部氮肥回收率的效果,添加脲酶抑制剂以及脲酶抑制剂与硝化抑制剂配施的两个处理效果较为理想,硝化抑制剂不宜单独添加。     

不同氮肥形态的氨挥发损失比较

利用从德国引进的农田土壤氨挥发风洞法测定系统,对不同N肥形态的肥料进行对比实验。结果表明,在相同施N量条件下,硝酸铵、硝酸铵钙、硫硝酸铵的氨挥发损失分别比尿素减少22.5%、3.2%和8.3%,不同N肥的氨挥发损失差异很大。相同条件下,尿素的氨挥发损失为25.7%,添加DMPP后氨挥发损失为27.6%;硫硝酸铵的氨挥发损失为18.6%,添加DMPP后为20.6%;添加DMPP对尿素和硫硝酸铵的氨挥发影响不显著。     

常规灌溉条件下施氮对温室土壤氨挥发的影响

为明确温室土壤的氨挥发特征,探讨适宜的减量施氮措施对氨挥发损失量及黄瓜产量的影响,在常规灌溉条件下设置了3个施氮（尿素）处理,采用通气法测定了冬春季黄瓜地中的氨挥发速率。结果表明：温室土壤在氮肥基施后7 d出现氨挥发速率峰值,但在氮肥追施后,施肥带与非施肥带的氨挥发速率峰值分别在第1 d与第5 d出现,氨挥发速率的峰值比氮肥基施时下降了8.6%～46.3%,施肥带的累积氨挥发量是非施肥带的0.91～1.54倍。冬春季黄瓜地的氨挥发损失量为16.7～26.6 kg/hm2,其中减施氮25%处理N900（900 kg/hm2）与减施氮50%处理N600（600 kg/hm2）与习惯施氮处理N1200（1 200 kg/hm2）相比,氨挥发损失量分别降低了22.1%和37.2%。而2 a黄瓜产量的平均值以处理N600（600 kg/hm2）最高,比处理N1200（1 200 kg/hm2）增加了6.52%。综合考虑氨挥发损失量、黄瓜产量及施氮量,在河北省的温室冬春季黄瓜生产中,比农民习惯氮用量（1 200 kg/hm2）减少25%～50%的措施是可行的。     

保护地菜田土壤氨挥发损失及影响因素研究

保护地过量施用氮肥是造成氮素氨挥发损失的主要原因。本文采用"密闭室间歇通气法"研究了常规施肥、常规+C/N、推荐施肥和单施有机肥4种施肥措施下保护地菜田土壤的氨挥发特性。结果表明:减少施肥量和秸秆还田技术能有效降低氨挥发损失;整个监测周期内,不同处理氨挥发量均较小,常规施肥处理损失量最高,占总施氮量的0.73%,化肥氮对氨挥发的贡献率较大(大于70%),不同处理氨挥发损失量大小顺序为常规施肥常规+C/N推荐施肥单施有机肥;氨挥发监测周期内表层土壤(0—1cm)pH值呈先下降后上升的趋势,下降幅度以常规施肥处理最大,约0.5个pH值单位;土壤pH值、0—1cm土层铵态氮含量与氨挥发速率呈显著正相关(P0.05)。     

尿素与缓释尿素配施添加DMPP对砂姜黑土氮素转化的影响

研究尿素与缓释尿素配施添加硝化抑制剂3,4-二甲基吡唑磷酸（DMPP）对砂姜黑土氮素转化的影响，为田间速效与缓释氮的合理配施提供理论依据。采用室内恒温、恒湿培养试验方法，试验设不施肥（CK）、单施尿素（N）、单施缓释尿素（S）、60%尿素+40%缓释尿素（NS）、尿素+DMPP（ND）、缓释尿素+DMPP（SD）、60%尿素+40%缓释尿素+DMPP（NSD）共七个处理，通过测定不同处理土壤中不同形态氮素含量，探究添加DMPP在单施尿素、单施缓释尿素及尿素与缓释尿素配施上对土壤氮素转化的不同影响。ND处理在培养第1~35 d内铵态氮含量均显著高于N处理（P<0.05），并有效延缓了铵态氮向硝态氮转化的时间。SD处理较之S处理在显著提高土壤中铵态氮含量的同时（P<0.05），也能有效抑制硝化作用，其硝化抑制有效作用时间在49 d左右，并且在此期间内能降低表观硝化率，提高硝化抑制率。与NS处理相比，NSD处理不仅能够显著提高土壤铵态氮含量（P<0.05），使铵态氮半衰期延长至18.6 d，硝化抑制率显著提高（P<0.05），表观硝化作用有效抑制时间延长了32 d左右。综合分析表明，尿素与缓释尿素配施添加DMPP在抑制氨氧化作用中效果明显，显著提高硝化抑制率（P<0.05），降低表观硝化率，有效延长了铵态氮在土壤中停留的时间，该措施为有效阻控农田氮素损失提供了科学依据。     

不同施氮量及施氮方式对水稻田氨挥发及氮肥利用率的影响

施用缓控释氮肥是降低稻田土壤氨挥发损失的常用措施之一。将缓控释氮肥与速效氮肥配施,可以解决水稻对氮素的需求与降低氮素损失之间的矛盾。在保证水稻产量的前提下,以减少稻田氨挥发损失、提高氮肥利用效率以及降低环境污染为目的,采用大田裂区试验的方法,设置不施氮肥和施氮量分别为60(N60)、120(N120)、180(N180)、240(N240)kg·hm-2 5个施氮水平,以及氮肥一次性施用(SF)及氮肥一基二追(TF)2种施肥方式,研究不同氮肥用量及运筹模式对水稻田氨挥发、氮肥利用率以及水稻产量的影响:结果表明,氮肥施用方式和施氮量对水稻田氨挥发损失量影响显著,同一施氮方式下,稻田土壤氨挥发损失量随着施氮量增加而增加,SF各处理氨挥发损失量为14.46～23.74 kg·hm-2,TF各处理的氨挥发损失量则为23.3～47.74 kg·hm-2,SF氨挥发损失量比TF降低37.9%～50.3%;氮肥施用方式显著影响氮肥表观利用率和氮肥偏生产力,SF和TF的最大氮肥表观利用率均出现在N180,分别为50.02%和38.68%;低施氮量(N60)和高施氮量(N240)时,TF氮肥偏生产力高于SF,而施氮量为120(N120)kg·hm-2、180(N180)kg·hm-2时,SF比TF氮肥偏生产力分别高出3.32和5.58 kg·kg-1;施氮量极显著影响水稻的氮素吸收量和氮肥农学利用率;SF和TF的最高产量分别出现在N180和N240,且SF高于TF,两者相差465.3 kg·hm-2。缓控释氮肥与速效氮肥配施一次性施肥可以有效降低稻田氨挥发损失,同时提升氮肥表观利用率和偏生产力,且能在施氮量较低的情况下获得较高产量,在水稻氮肥管理上具有应用价值。     

华北农田土壤氨挥发原位测定研究

通过系数矫正后的双层海绵吸收法对不同N肥处理和NPK配施下氨气挥发损失特征研究结果表明,N肥施用方式、土壤温度以及灌溉是影响氨挥发的重要因素。施肥后氨挥发损失量为0.67~9.91kg/hm2,占施N量的0.41%~5.0%。玉米季氨挥发量占全年挥发损失的80%以上。尿素与过磷酸钙配施可显著降低氨挥发,在此基础上施用KCl,尿素氨挥发损失变化不明显。     

东北黑土玉米单作体系氨挥发特征研究

采用通气法测定了东北黑土玉米单作体系田间土壤的原位氨挥发。试验设5个氮肥用量处理,即:施氮量（N）分别为0、150、225和300 kg/hm2（用N0、N1、N2 和N3表示）,基施氮肥和拔节期追肥各1/2,其中N3为习惯施肥;同时设置优化施肥处理N4,用量为N 225 kg/hm2,基施氮肥、拔节期和孕穗期追肥各1/3。结果表明,来自肥料的氨挥发持续时间较短,一般发生在施肥后的7 d内。由于追肥期高温低湿,追肥期氨挥发量显著高于基施氮肥。随施氮量增加,氨挥发损失增加;优化施肥（N4）的氨挥发损失量明显低于习惯施肥,N1、N2、N3和N4处理来自氮肥的氨挥发依次为N 5.09、9.18、13.47和7.14 kg/hm2,相当于施氮量的3.39%、4.08%、4.49%和3.17%。可见,优化施肥对于我国东北集约化农区节省氮肥和提高氮肥利用率有重要意义。     

秸秆全量还田与氮肥用量对水稻产量、 氮肥利用率及氮素损失的影响

【目的】在我国水稻生产中探讨秸秆全量还田与氮肥配施的理论与技术,阐明秸秆还田对水稻产量、 氮素利用率及氮素损失的影响,对于提高水稻产量和氮素利用效率、 减少氮污染具有重要意义。【方法】2009~2011年,以水稻南粳46为材料,在江苏常熟农业生态实验站进行原状土柱模拟试验。试验采用裂区设计,主区为秸秆全量还田(S)和无秸秆还田(S0); 副区为氮肥用量(N),设置N 120、 180、 240和300 kg/hm2 4个氮水平,以不施氮肥(N0)为对照。分析了水稻基肥期、 分蘖期、 穗肥期的氨挥发量和土壤80 cm处渗漏水全氮含量,土壤0—15 cm全氮含量,水稻产量,以及水稻籽粒和秸秆氮含量,计算水稻生育期氮肥的氨挥发损失率、 淋溶损失率、 土壤残留率以及水稻的氮肥利用效率。【结果】水稻产量随氮肥适宜用量增加而增加,与单施氮肥相比,秸秆还田下水稻平均增产6.3%,其中N 240 kg/hm2 处理产量最高; 水稻的氮肥利用率随施氮量的增加呈下降趋势,秸秆还田能够提高水稻的氮肥利用率,氮肥农学效率和氮肥表观利用率较单施氮肥分别提高1.4~3.4 kg/kg和1.8%~4.2%; 水稻田氨挥发损失量、 氮肥淋溶损失量和土壤残留氮量均随施氮量的增加而增加,在N 240 kg/hm2水平下,秸秆还田氨挥发损失量增加18.2%、 土壤残留氮量增加10.1 kg/hm2,减少氮素淋溶损失量30.9%,氮肥总损失率降低6.0%。【结论】在秸秆全量还田下,配施适量的氮肥,可以提高水稻对氮肥的利用率,增加产量,同时减少氮肥损失。本试验中,以麦秸全量还田配施N 240 kg/hm2为最优组合。     

种稻下氮肥的氨挥发及其在氮素损失中的重要性的研究

在特制密闭盆钵甲,研究了¹⁵N标记氮肥作水稻基肥混施时,氨的挥发及其在氮素损失中的重要性,随着通气速率的增高,氨的挥发及其在氮素损失中的重要性也增大,至换气频率达15-20次/分时即接近或达到最大值.在酸性水稻土上,硫铵的氮素损失的主要途径是反硝化作用,特别是气温较低的月份;尿素的氮素损失途径,在气温较低的月份中以反硝化作用为主,在温度较高的月份中,则氨的挥发与反硝化作用都是重要的;对碳铵来说,氨的挥发和反硝化作用都是氮素损失的重要途径.在石灰性土壤上,碳铵的氮素损失的主要途径是氨的挥发,而在硫铵和尿素的氮素损失中,氨的挥发和反硝化作用则都是重要的.     

有机无机肥长期定位试验土壤小麦季氨挥发损失及其影响因素研究

氨挥发是肥料氮素损失的重要途径之一,损失率因土壤类型、气候条件、肥料用量、施肥时间和方式等不同而存在很大差异。为了筛选提高氮肥利用率的肥料运筹方式,本文利用长期定位试验平台,采用间歇密闭通气法,研究了有机无机肥长期施用条件下小麦季土壤氨挥发损失及其影响因素。结果表明,不同肥料种类和配施强烈地影响着土壤氨挥发,在150kgN·hm^-2用量下小麦季氨挥发损失量以NK和有机肥处理为最高,分别达到17．89和15．70kgN·hm^-2,占氮肥用量的10．47％-11．93％,显著高于NPK、NP和有机无机肥配施（1／20M）处理。土壤氨挥发速率与气温呈显著正相关,基肥施用后灌水可以有效地降低氨挥发损失。NPK肥料平衡施用或者有机无机肥配施可以减少氨挥发损失。     

Effects of nitrification inhibitors on transformations of urea nitrogen in soils

The effects of three patented nitrification inhibitors on transformations of urea N in soils were studied by determining the effects of these compounds (10 μg/g of soil) on urea hydrolysis, ammonia volatilization. and production of ammonium, nitrite, and nitrate in soils incubated under aerobic conditions (30°C, 60% WHC) after treatment with urea (400 μg of urea N/g of soil). The inhibitors used (N-Serve, ATC, and CL-1580) had little, if any, effect on urea hydrolysis, but they retarded nitrification of the ammonium formed by urea hydrolysis and increased gaseous loss of urea N as ammonia. They also decreased the amount of (urea + exchangeable ammonium + nitrite + nitrate) — N found in urea-treated soils after various times.Two of the soils used accumulated substantial amounts of nitrite(> 160 μg of nitrite N/g of soil) when incubated under aerobic conditions after treatment with urea. Addition of nitrification inhibitors to these soils eliminated or substantially reduced nitrite accumulation and greatly retarded nitrate formation, but had little, if any, effect on the recovery of urea N as (urea + exchangeable ammonium + nitrite + nitrate + ammonia) — N after various times. This finding and other observations reported indicate that the “nitrogen deficits” observed in studies of urea N transformations in soils may not largely be due to gaseous loss of urea N through chemodenitrification and are at least partly due to volatilization and fixation of the ammonium formed by urea hydrolysis in soils. The work reported also indicates that N-Serve and other nitrification inhibitors may prove useful for reduction of the nitrite toxicity problems associated with the use of urea as a fertilizer but that application of such inhibitors in conjunction with fertilizer urea, when surface applied, may promote gaseous loss of urea N as ammonia.     

碳酸氢铵和尿素在山东省主要土壤类型上的氨挥发特性研究

采用全程密闭通气法研究了山东省四种主要土壤类型 (棕壤 ,褐土 ,潮土和砂姜黑土 ) ,尿素和碳酸氢铵表施后的氨挥发特点。结果表明 :碳酸氢铵初始的氨挥发强度大于尿素 ,而氨挥发总量小于尿素 ,尿素在四种类型土壤上铵挥发强度次序为 :褐土 >潮土≈砂姜黑 >棕壤 ,氨挥发总量次序为 :褐土 >潮土≈砂姜黑土 >棕壤 ;碳酸氨氢在四种类型土壤上氨挥发强度次序为 :褐土 >潮土≈砂姜黑土 >棕壤 ,挥发总量次序为 :褐土 >棕壤 >潮土≈砂姜黑土。影响氨挥发的因素主要有 :氮素形态 ,土壤 pH、CEC、粘粒含量和粘土矿物类型、有机质含量等 ,但在不同土壤中其影响的主导因素又有较大差异。     

Applied Model for Estimating Potential Ammonia Loss from Surface-Applied Urea

Ammonia loss from urea fertilizer is a major concern to farmers all over the world. Various environmental factors such as temperature, soil water content, wind speed, pH, rainfall, relative humidity, cation exchange capacity (CEC), soil organic matter, and others influence ammonia volatilization loss. The objective of this work was to establish a model for estimating ammonia loss utilizing published data. Also, using current day inputs (temperature, wind speed, and known soil pH) estimates could relate risk to producers considering surface applications of urea fertilizer without incorporation. Linear models for soil pH and ammonia loss, ambient temperature and ammonia loss, and wind speed and ammonia loss were determined based on more than 40 published articles. Final estimates of ammonia loss from surface applications of urea employed an additive effects model using inputs for pH, temperature, and wind speed. Web access to this model can be located at www.nue.okstate.edu/ammonia_loss.htm.     

氮肥用量对太湖水稻田间氨挥发和氮素利用率的影响

Ammonia volatilization losses, nitrogen utilization efficiency, and rice yields in response to urea application to a rice field were investigated in Wangzhuang Town, Changshu City, Jiangsu Province, China. The N fertilizer treatments, applied in triplicate, were 0 （control）, 100, 200, 300, or 350 kg N ha^-1. After urea was applied to the surface water, a continuous airflow enclosure method was used to measure ammonia volatilization in the paddy field. Total N losses through ammonia volatilization generally increased with the N application rate, and the two higher N application rates （300 and 350 kg N ha^-1） showed a higher ratio of N lost through ammonia volatilization to applied N. Total ammonia loss by ammonia volatilization during the entire rice growth stage ranged from 9.0% to 16.7% of the applied N. Increasing the application rate generally decreased the ratio of N in the seed to N in the plant. For all N treatments, the nitrogen fertilizer utilization efficiency ranged from 30.9% to 45.9%. Surplus N with the highest N rate resulted in lodging of rice plants, a decreased rate of nitrogen fertilizer utilization, and reduced rice yields. Calculated from this experiment, the most economical N fertilizer application rate was 227 kg ha^-1 for the type of paddy soil in the Taihu Lake region. However, recommending an appropriate N fertilizer application rate such that the plant growth is enhanced and ammonia loss is reduced could improve the N utilization efficiency of rice.     

Ammonia Volatilization from Soil,Dry-Matter Yield,and Nitrogen Levels of Italian Ryegrass

Nitrogen (N) loss by ammonia (NH₃) volatilization is the main factor for poor efficiency of urea fertilizer applied to the soil surface. Losses can be suppressed by addition of zeolite minerals to urea fertilizer. The objective of this study was to evaluate ammonia volatilization from soil and dry-matter yield and nitrogen levels of Italian ryegrass. A greenhouse experiment was carried out with the treatments of urea, urea incorporated into soil, urea + urease inhibitor, urea + zeolite, ammonium nitrate, and unfertilized treatment. Ammonia was captured by a foam absorber with a polytetrafluoroethylene tape. There were few differences between zeolite and urease inhibitor amendments concerning NH₃ volatilization from urea. Results indicate that zeolite minerals have the potential to improve the N-use efficiency and contributed to increasing N uptake. Zeolite and urea mixture reduced 50% the losses by volatilization observed with urea.     

Ammonia volatilization from Vertisols

Farmers want to minimize losses of nitrogen (N) by volatilization of ammonia when adding fertilizers and improve fertilizer recovery of N by plants. We aimed to quantify the losses of N through NH₃ volatilization as affected by soil moisture content, type of fertilizer, and placement method in Vertisols in Kenya, and conducted three experiments for the purpose under controlled conditions in the laboratory. We found that NH₃-N losses were greatest at 80% water holding capacity, which we ascribed to the ready availability of water to dissolve the fertilizer at that water content. The soil's cation exchange capacity (CEC) did not influence volatilization, whereas the soil's pH indicated the potential of the soil to volatilize ammonia. Ammonia losses from the fertilizers were in the order urea > ammonium sulphate > ammonium nitrate applied. Incorporating fertilizer within the 0–5 cm soil layer more than halved NH₃ volatilization but did not prevent it completely. These results indicate that soil pH, rather than CEC, is the main inherent characteristic influencing ammonia volatilization from Vertisols. Ammonium-based fertilizers should be incorporated within the 0–5 cm soil layer, or preferably somewhat deeper, to avoid losses via NH₃ volatilization, particularly in alkaline soils. Nitrate fertilizers are preferable to urea where the risks of NH₃ volatilization are large, provided due consideration is given to denitrification risks.