太湖水稻土麦季尿素氨挥发损失

Ammonia volatilization losses from urea applied as a basal fertilizer and a top dressing at tillering stage in a wheat field of Taihu Region, China, were measured with a micrometeorological technique. Urea as fertilizer was surface broadcast at 81 (low N) and 135 (high N) kg N ha-1 as basal at the 3-leaf stage of the wheat seedling on December 2002, and 54 (low N) and 90 (high N) kg N ha-1 as top dressing on February 2003. Ammonia volatilization losses occurred mainly in the first week after applying N fertilizer and mainly during the period after basal fertilizer application, which accounted for more than 80% of the total ammonia volatilization over the entire wheat growth period. Regression analysis showed that ammonia volatilization was affected mainly by pH and NH4^ -N concentration of the surface soil and air temperature.Ammonia volatilization flux was significantly correlated with pH and NH4^ -N concentration of the surface soil and with daily air average temperature and highest temperature. Thus, application of urea N fertilizer to wheat should consider the characteristics of ammonia volatilization in different periods of N application so as to reduce ammonia losses.     

中国西北旱地小麦和玉米提高产量与水分利用率的氮肥管理效果

A field experiment with four treatments and four replicates in a randomized complete block design was conducted at the Changwu Experimental Station in Changwu County, Shaanxi Province, of Northwest China from 1998 to 2002. The local cropping sequence of wheat, wheat-beans, maize, and wheat over the 4-year period was adopted. A micro-plot study using ^15N-lahelled fertilizer was carried out to determine the fate of applied N fertilizer in the first year. When N fertilizer was applied wheat （years 1, 2 and 4） and maize （year 3） grain yield increased significantly （P 〈 0.05） （〉 30%）, with no significant yield differences in normal rainfall years （Years 1, 2 and 3） for N application at the commonly application rate and at 2/3 of this rate. Grain yield of wheat varied greatly between years, mainly due to variation in annual rainfall. Results of ^15N studies on wheat showed that plants recovered 36.6%-38.4% of the N applied, the N remained in soll （0-40 cm） ranged from 29.2% to 33.6%, and unaccounted-for N was 29.5%-34.2%. The following crop （wheat） recovered 2.1%- 2.8% of the residual N from N applied to the previous wheat crop with recovery generally decreasing in the subsequent three crops （beans, maize and wheat）.     

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.     

镉、铅、锌对红壤微生物生物量的影响

Nitrogen(N)losses from ammonium bicarbonate or urea applied to wheat and then followed immediately by irrigation were investigated.Ammonia volatilization was determined by a micrometeorological method (ammonia sampler),total N loss was estimated by the ^15N mass balance method ,and denitrification loss was measured by the diference method(calculated from the difference between the total N loss and ammonia loss) and a direct method (measuring the emission of (N2 N2O)-^15N).Total ammonia losses from ammonium bicarbonate and urea in 33 days were 8.7% and 0.9% of the applied nitrogen ,respectively.The corresponding total N losses were 21.6% and 29.5%,Apparent denitrification losses(by the difference method) were rather high,being 12.9% from ammonium bicarbonate and 28.6% from urea .However,no emission of (N2 N2O)-^15N was detected using the direct method.     

Fate of Fertilizer Nitrogen Applied to Crops Grown on Fluvo-Aquic Soil in Huang-Huai-Hai Plain

The fate of urea-and ammonium bicarbonate(ABC)-nitrogen (N) applied by prevailing traditional techniques to winter wheat (Triticum aestivum L.)or maize (Zea mays L.)grown in the fields of Fluvo-aquic soil was investigated using ^15N tracer-micro-plot technique.Results show that:(1) at maturity of wheat,N recovery in plants and N losses of urea and ABC applied at seeding in autumn were 31-39%,and 34-46%,respextively,while the corresponding figures for side-banding at 10 cm depth in early spring were 51-57%,and 5-12%;surface-broadcast of urea followed by irrigation at early spring was as efficient as the side-banding in improving N recovery in plants and reducing N loss,however,such techuique was found less satisfactory with ABC.(2)At the maturity of maize,N recovery in the plants and N loss of urea and ABC sidebanded at seedling stage or prior to tasseling ranged from 23% to 57%,and 9% to 26%,respectively.(3) Either in Wheat or in maize experiment,the majority of residual fertilizer N in soil profile (0-60cm) was in the form of biologically immobilized organic N,however,the contribution of ammonium fixation by clay minerals increased markedly nwith depth in soil profile.(4) Though the proportion of residual fertilizer N was generally highest in the top 20 cm soil layer,considerable reaidual N (nostly 6-11% of the N applied)was found in 60-100 cm soil layers.     

Leaching and Transformation of Nitrogen Fertilizers in Soil After Application of N with Irrigation： A Soil Column Method

A soil column method was used to compare the effect of drip fertigation （the application of fertilizer through drip irrigation systems, DFI） on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation （SFI）, and to study the leaching loss and transformation of three kinds of nitrogen fertilizers （nitrate fertilizer, ammonium fertilizer, and urea fertilizer） in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N （NH4^＋-N ＋ NO3^--N） in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control （without urea addition）, on the first day when soils were fertigated with urea, there were increases in NH4^＋-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH4^＋-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH4^＋-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH4^＋-N fixation or volatilization in the soil during the fertigation process.     

基于傅里叶变换中红外光声光谱的土壤顶空氨浓度的原位测定

Ammonia(NH3) volatilization is one of the important pathways of nitrogen loss in alkaline soil, and the NH3 concentration in soil headspace is directly linked with the NH3 volatilization. Ammonia was characterized by Fourier transform mid-infrared photoacoustic spectroscopy(FTIR-PAS) and two typical absorption bands in the region of 850–1 200 cm-1were observed, which could be used for the prediction of NH3 concentration in the soil headspace. An alkaline soil from North China was involved in the soil incubation, pot and field experiments under three fertilization treatments(control without N input(CK), urea and coated urea). Ammonia concentrations in the soil headspace were determined in each experiment. In the soil incubation experiment, the NH3 emissions were initiated by the N input, reached the highest concentration on day 2, and decreased to the level as measured in CK after 8 d, with significantly higher NH3 emissions in the urea treatment compared to coated urea treatment, especially during the first 4 d. The NH3 concentration in soil headspace of the pot experiment showed the similar dynamics as that in the incubation experiment; however, the NH3 concentration in the soil headspace in the field experiment demonstrated a significantly different emission pattern with those of the incubation and pot experiments, and there was a 4-d delay for the NH3 concentration. Therefore, the NH3 concentration in the incubation and pot experiments could not be directly used to model the real NH3 emission in the field due to the differences in fertilization method and application rate as well as soil temperature and soil disturbance. It was recommended that light irrigation in the second week after fertilization and involvement of controlled release coated urea could be used to significantly decrease N loss from the perspective of NH3 volatilization.     

太湖地区稻麦轮作下氮素径流和淋洗损失

Although nitrogen （N） loss through runoff and leaching from croplands is suspected to contribute to the deterioration of surrounding water systems, there is no conclusive evidence for paddy soils to prove this hypothesis. In this study, field plot experiments were conducted to investigate N losses through runoff and leaching for two consecutive years with 3 N fertilization rates in rice （Oryza sativa L.）-wheat （Triticum aestivum L.） rotations in the Taihu Lake region, China. A water collection system was designed to collect runoff and leachates for both the rice and wheat seasons. Results showed that dissolved N （DN）, rather than particulate N （PN）, was the main form of N loss by runoff. The NO3^--N concentration in runoff was between 0.1 and 43.7 mg L^-1, whereas the NH4^＋-N concentration ranged from below detection limit to 8.5 mg L^-1. Total N （TN） loads by runoff were 1.0-17.9 and 5.2-38.6 kg ha^-1 during rice and wheat seasons, respectively, and the main loss occurred at the early growing stage of the crops. Nitrogen concentrations in leachates during the rice seasons were below 1.0 mg L^-1 and independent of the N application rate, whereas those during the wheat season increased to 8.2 mg L^-1 and were affected by the fertilizer rate. Annual losses of TN through runoff and leaching were 13.7-48.1 kg ha^-1 from the rice-wheat cropping system, accounting for 5.6%-8.3% of the total applied N. It was concluded that reduction in the N fertilization rate, especially when the crop was small in biomass, could lower the N pollution potential for water systems.     

中国南方大棚蔬菜地氮平衡与损失

High rates of fertilizer nitrogen (N) are applied in greenhouse vegetable fields in southeastern China to maximize production;however,the N budgets of such intensive vegetable production remain to be explored.The goal of this study was to determine the annual N balance and loss in a greenhouse vegetable system of annual rotation of tomato,cucumber,and celery at five N (urea) application rates (0,348,522,696,and 870 kg N ha-1 year-1).Total N input to the 0-50 cm soil layer ranged from 531 to 1 053 kg ha-1,and N fertilizer was the main N source,accounting for 66%-83% of the total annual N input.In comparison,irrigation water,wet deposition,and seeds in total accounted for less than 1% of the total N input.The fertilizer N use efficiency was only 18% under the conventional application rate of 870 kg N ha-1 and decreased as the application rate increased from 522 to 870 kg N ha-1.Apparent N losses were 196-201 kg N ha-1,of which 71%-86% was lost by leaching at the application rates of 522-870 kg N ha-1.Thus,leaching was the primary N loss pathway at high N application rates and the amount of N leached was proportional to the N applied during the cucumber season.Moreover,dissolved organic N accounted for 10% of the leached N,whereas NH3 volatilization only contributed 0.1%-0.6% of the apparent N losses under the five N application rates in this greenhouse vegetable system.     

基施磷肥对石灰性土壤上番茄产量的影响

A lysimeter experiment with undisturbed soil profiles was carried out to study nitrogen cycling and losses in a paddy soll with applications of coated urea and urea under a rice-wheat rotation system in the Taihu Lake region from 2001 to 2003. Treatments for rice and wheat included urea at conventional, 300 （rice） and 250 （wheat） kg N ha^-1, and reduced levels, 150 （rice） and 125 （wheat） kg N ha^-1, coated urea at two levels, 100 （rice） and 75 （wheat） kg N ha^-1, and 150 （rice） and 125 （wheat） kg N ha^-1, and a control with no nitrogen arranged in a completely randomized design. The results under two rice-wheat rotations showed that N losses through both NH3 volatilization and runoff in the coated urea treatments were much lower than those in the urea treatments. In the urea treatments N runoff losses were significantly （P 〈 0.001） positively correlated （r = 0.851） with applied N. N concentration in surface water increased rapidly to maximum two days after urea application and then decreased quickly. However, if there was no heavy rain within five days of fertilizer application, the likelihood of N loss by runoff was not high. As the treatments showed little difference in N loss via percolation, nitrate N in the groundwater of the paddy fields was not directly related to N leaching. The total yield of the two rice-wheat rotations in the treatment of coated urea at 50% conventional level was higher than that in the treatment of urea at the conventional level. Thus, coated urea was more favorable to rice production and environmental protection than urea.     

基于DNDC模型的华北典型农田氮素损失分析及综合调控途径

氮素损失对农业生产造成的影响已成为当前研究的热点,模型是对氮素损失影响评价及定量化研究的有效手段。利用华北典型农田冬小麦-夏玉米轮作种植模式的作物产量、氮素淋失量等田间观测数据对DNDC模型进行了验证,并采用验证后的DNDC模型对该种植模式的氮素损失进行了定量评价,提出了综合考虑作物产量、氮素淋失量、N2O排放量以及NH3挥发损失的综合调控途径。结果表明,DNDC模型较好地模拟了冬小麦-夏玉米轮作系统作物的产量、氮素淋失的动态变化规律,以及土壤中NO3--N和NH4+-N的残留量,说明DNDC已具备模拟农田生态系统中土壤氮素生物地球化学过程的能力。模型模拟结果表明,在传统农业管理措施下,氮素通过淋失、N2O排放以及NH3挥发损失的量分别达到49.4 kg(N).hm-2.a-1、17.71kg(N).hm-2.a-1和144.8 kg(N).hm-2.a-1。综合考虑氮素损失途径,提出了适合当地农业生产条件的最优化管理措施,即减小当前常规施氮量到340 kg(N).hm-2.a-1,提高玉米秸秆还田率到100%,并保持灌溉量不变。相比常规管理措施,最优化管理措施氮素淋失量为14.1 kg(N).hm-2.a-1,降低71.5%,N2O排放量为14.91kg(N).hm-2.a-1,降低15.8%,NH3挥发损失量为117.2 kg(N).hm-2.a-1,降低19.1%,而对作物产量基本不造成明显影响。该评价结果可直接用于农业生产实践。     

露地种植大白菜的氮肥效应与氮素损失研究

采用田间小区和微区试验,研究了施用化学氮肥在露地大白菜上的氮肥效应和氮素损失。氮素总损失用15N示踪法测定,氨挥发用通气密闭室法测定,反硝化损失用乙炔抑制原状土柱培养法测定,不加乙炔测定N2O排放。结果表明,施用化学氮肥增产显著,用差值法计算得到的氮肥利用率在25.3%4～7.2%之间,相应的示踪法氮肥利用率为18.1%2～4.6%。化学氮肥显著增加了氨挥发、反硝化和N2O排放等气态氮损失;其中氨挥发占施氮量的0.97%1～7.1%,反硝化占4.33%8～.55%,N2O排放在1.09%1～.63%之间变化。大白菜收获时9.2%～10.9%的标记尿素被淋洗到40.cm以下土层。试验期间尿素的氮素总损失达41.1%4～8.1%,以表观淋洗损失最为严重,其次是氨挥发,而反硝化损失最低。与普通尿素相比,包衣尿素明显降低了氨挥发。     

硝化抑制剂影响小麦产量、N2O与NH3排放的研究

通过田间小区试验研究不同施氮水平下,施用硝化抑制剂CP对小麦产量、氮素利用率、氧化亚氮(N_2O)排放与氨(NH_3)挥发的综合影响规律。结果表明:在施氮水平为140 kg/hm2与180 kg/hm2时,施用CP促使小麦产量分别显著增加17.8%和15.4%,在同一施氮水平下,施用CP促进小麦氮素利用率提高11.3%~25.2%。施用硝化抑制剂CP可以降低麦季(特别是基肥与穗肥施用时期)土壤N_2O的排放速率,并显著减少39.3%~53.7%的累积N_2O排放量。但是在两个施氮水平下,施用CP导致麦季NH_3挥发量增加1.46~1.75倍,而且此效应主要发生于基肥与穗肥观测期。本研究说明:在麦季施用硝化抑制剂CP可以提高氮素利用率,从而提高小麦产量,并且能减少N_2O排放,但同时会导致一定程度的NH_3挥发增加,需加以控制。     

太湖地区冬小麦季土壤氨挥发与一氧化氮排放研究

采用密闭室连续抽气法和静态箱法同步研究了太湖地区冬小麦季田间小区试验中不同施氮处理的氨挥发与一氧化氮（NO）排放的规律。结果表明,麦季氨挥发主要发生在施肥后 7～10d,以基肥期挥发量最大,为NH3-N 0.49～9.36 kg/hm2,占整个麦季观测期间挥发量的60.4%～74.7 %;NO的排放则主要发生在施用基肥后的30d 内,量虽小但持续时间较长,排放速率为NO-N 0.009～0.304 mg/(m2.h),该时期总损失量为NO-N 0.68～1.23 kg/hm2,约占整个麦季观测期排放量的 93%。氨挥发和 NO 排放均随施氮量的增加而增加。各施氮处理麦季观测期的氨挥发总损失量为NH3-N 7.6～12.6 kg/hm2,损失率4.62%～5.26%;NO排放总量为NO-N 0.73～1.3 kg/hm2,损失率0.27%～0.41%。研究结果对综合评价太湖地区麦季氮肥的气态损失及其环境效应、指导合理施肥都具有重要意义。     

利用膜进样质谱法测定不同氮肥用量下反硝化氮素损失

利用膜进样质谱仪(MIMS)测定了太湖流域典型稻田不同氮肥施用梯度下,土壤反硝化氮素损失量,同时也对氨挥发通量进行了观测。根据两年的田间试验结果得到:在常规施氮处理(N300)下,每年平均有54.8 kg/hm~2 N通过反硝化损失,有约54.0 kg/hm~2 N通过氨挥发损失,分别占肥料施用量的18.3%和18.0%,两者损失量相当。通过反硝化和氨挥发损失的氮素量随着氮肥用量增加而增加,田面水的NH_4~+-N、NO_3~–-N、DOC和pH浓度影响稻田土壤反硝化速率。在保产增效施氮处理(N_270)下,氮肥施用量比常规减少10%,水稻产量增加了5.5%,而通过反硝化和氨挥发损失的氮素量分别下降了1.1%和3.1%,氮肥利用率提高了约5.5%。在增施氮肥处理(N375)下,因作物产量增加使得氮肥利用率比N300增加,但通过氨挥发和反硝化的氮素损失量也最大。因此,通过综合集约优化田间管理措施,降低氮肥用量,可实现增产增效的目的。     

稻草还田对烟田追肥气态氮损失及相关微生物的影响

研究不同农业措施下N2O和NH3的排放，对减缓温室效应及雾霾治理有重要意义。针对烟田追肥浇施的特殊管理方式，以水稻烤烟轮作定位试验为平台，于2017年选择单施化肥（NPK）、化肥+稻草还田（NPKS）、化肥+稻草还田+饼肥（NPKSB）3个处理，研究稻草还田对追肥气态氮损失及其相关微生物群落结构的影响。研究显示，烤烟追肥后土壤NH3挥发和N2O排放速率开始上升，2～3d达到最大，之后开始下降。NPK处理追肥氨挥发氮量为1.45±0.04 kg/hm2、N2O排放氮量为2.49±0.23 kg/hm2，气态氮损失中以N2O排放为主。与单施化肥相比，稻草还田配施化肥提高了土壤含水量、改变了氧化亚氮还原酶基因（nosZ）和氨氧化细菌（AOB，Ammonia Oxidizing Bacteria）的微生物群落结构，其根瘤菌目相对丰度显著降低、红螺菌目相对丰度显著升高；同时N2O排放量增加了55.35%、氨挥发氮量显著降低了11.43%，气态氮损失显著增加。与单施化肥相比，化肥+稻草还田+饼肥处理提高了土壤含水量、改变了nosZ和AOB基因的微生物群落结构，其伯克尔霍尔德氏菌目相对丰度显著提高。化肥+稻草还田+饼肥处理N2O排放量与单施化肥差异不显著，氨挥发氮量显著降低了8.91%，但两者气态氮损失差异不显著。化肥+稻草还田+饼肥处理N2O排放量较化肥+稻草还田处理降低27.82%，但两者氨挥发量差异不显著。综上所述，秸秆还田抑制了土壤氨挥发、激发了N2O排放，稻草还田配施饼肥能够降低土壤氨挥发、抑制稻草还田引起的N2O排放。     

传统和优化施氮对春玉米产量、氨挥发及氮平衡的影响

【目的】本文通过在陕西省长武县(CW)和吉林省梨树县(LS)的春玉米田间试验,研究了传统和优化施氮对春玉米产量、土壤氨挥发及氮平衡的影响,以探讨春玉米氮肥优化的潜力及其对农田氨减排的效果。【方法】试验设对照、传统施氮(长武N 250 kg/hm2,梨树N 300 kg/hm2)及优化施氮(N 200 kg/hm2)3个处理,分别以N0、Ncon、Nopt表示。氨挥发采用德尔格氨管法(简称DTM法)进行原位测定,通过田间气象因素的校正计算氨挥发累积量。【结果】长武和梨树点不同施氮处理下春玉米的产量结果表明,除对照(长武7.9 t/hm2、梨树3.8 t/hm2)外,传统和优化施氮处理间均无显著差异(长武10.6 10.8 t/hm2,梨树9.5 9.6 t/hm2)。玉米氮肥利用率表现为优化施氮(44.3%44.5%)显著高于传统施氮(33.6%36.4%),其中长武点氮肥利用率提高了8.1个百分点,梨树点氮肥利用率增加了10.7个百分点。氨挥发田间监测结果显示,基肥翻耕入土后,伴随降雨的产生,长武和梨树点均未产生氨挥发。喇叭口追肥期表施氮肥后,长武和梨树点均产生大量氨挥发(占追施尿素氮量的16%22%),减少追肥用量N 30 kg/hm2(长武点)和N 100 kg/hm2(梨树点)能显著减少氨挥发损失N 8和15 kg/hm2。土壤-春玉米系统氮平衡估算的结果显示,与长武点氮素表观矿化N 97 kg/hm2相比,梨树点仅为N 16 kg/hm2。优化施氮比传统施氮处理显著降低表观氮素盈余N 48 88 kg/hm2。长武点各施氮处理的表观氮素盈余中,约46%的氮素残留在0—1 m的土壤中,54%损失到环境中,氨挥发占总损失的15%30%;梨树点表观氮素盈余中,35%损失到环境中,其中氨挥发占总损失的54%75%,约有65%残留在0—1m的土壤中。梨树点传统施氮处理0—1 m土层的氮素残留达N 140 kg/hm2,部分残留在土壤中的氮素也将面临淋洗、硝化和反硝化等损失的风险。与优化施氮相比传统施氮氮素表观损失增加了约N 30 40 kg/hm2,除氨挥发损失外,淋洗和硝化/反硝化等也是土壤-春玉米系统中不可忽视的氮素损失途径。【结论】我国春玉米主产区农民传统的氮肥用量偏高,增产效应不明显,氮肥损失风险加剧,尤其是氨挥发损失较大,氮肥的优化潜力高达20%33%,相当于可减少施氮N 50 100kg/hm2。     

菜地追施猪粪沼液后NH3和N2O排放特征及氮损失率

将厌氧发酵残留物作为肥料还田是其资源化利用的有效途径,但国内外对其还田后氨气（NH3）和氧化亚氮（N2O）的排放特征及氮素利用率的报道较少。本研究通过微区试验,探讨了冬季和夏季大棚菜地追施猪粪沼液（DPS）后NH3和N2O的排放速率及氮素损失率。结果发现, 追施DPS后菜地NH3挥发激增,通常发生在施肥后的48 h 内;而N2O排放量在第一次施肥后大幅增加,随后逐步趋于稳定。追施DPS的处理其NH3和N2O的排放量均显著高于施用化肥的处理,冬季和夏季二者的损失量分别占肥料总量的16.4%～23.2%和24.7%～27.5%。土壤温度、水分和pH对沼液中氮素以NH3和N2O的形式损失的影响较大。