Ammonia Volatilization from Winter Wheat Field Top Dressed with Urea

Ammonia volatilization was measured with a continuous air flow enclosure method from a winter wheat field in the Experimental Farm of Jurong Agricultural School to investigate its main influencing factors. The experiment with five treatments in triplicate, no N (control), 100, 200 and 300 kg N ha-1 with rice straw cover at a rate of 1500 kg ha-1 and 200 kg N ha-1 without rice straw, started when the winter wheat was sown in 1994. Sixty percent of the total amount of N applied was hasal and 40% was top-dressed. The measurement of ammonia volatilization was immediately conducted after urea was top-dressed on soil surface at wheat elongation stage in spring of 1996 and 1997. The results showed that there was a diurnal variation of ammonia volatilization rate from the winter wheat field, which synchronized with air temperature. N losses through ammonia volatilization increased with increasing N application rate, but the ratio of N lost through ammonia volatilization to applied N was not significantly affected by N application rate. The coverage of rice straw had no significant effect on ammonia volatilization. Soil moisture and rain events after urea was top-dressed affected ammonia volatilization significantly.

Ammonia Volatilization Losses from Urea Applied to Wheat on a Paddy Soil in Taihu Region, China

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.

Ammonia Volatilization from Urea Applied to Acid Paddy Soil in Southern China and Its Control

Results showed that ammonia loss from urea broadcast into floodwater and incorporated into soil at transplanting was as high as 40% of applied N,and the corresponding total nitrogen (N) loss was 56%.Ammonia loss was measured with simplified micrometeorological method (ammonia sampler),and total N loss was concurrently measured using ^15N balance technique.The experiment was conducted under strong sunshine conditions on acid paddy soil derived from Quaternary red clay.The ammonia loss in this particular condition was much greater than those obtained from previous studies when urea was also applied to acid paddy soil but under cloudy conditions.It is concluded that the strong sunshine conditions with high temperature and shallow floodwater during the period of present experiment favoured ammonia volatilization.Application of stearyl alcohol on the surface of the floodwater reduced ammonia loss to 23% of applied N.However,the effect of stearyl alcohol was short-lived,probably due to the microbiological decomposition.

Ammonia volatilization losses and ^(15)N balance from urea applied to rice on a paddy soil

Ammonia volatilization loss and 15N balance were studied in a rice fie ld at three different stages after urea application in Taihu Lake area with a mi crometeorological technique. Factors such as climate and the NH4+-N concentratio n in the field floodwater affecting ammonia loss were also investigated. Results show that the ammonia loss by volatilization accounted for 18.6%—38.7% of urea applied at different stages, the greatest loss took place when urea was applied at the tillering stage, the smallest at the ear bearing stage, and the intermed iate loss at the basal stage. The greatest loss took place within 7 d following the fertilizer application. Ammonia volatilization losses at three fertilization stages were significantly correlated with the ammonium concentration in the fie ld floodwater after the fertilizer was applied. 15N balance experiment indicated that the use efficiency of urea by rice plants ranged between 24.4% and 28.1%. At the early stage of rice growth, the fertilizer nitrogen use efficiency was ra ther low, only about 12%. The total amount of nitrogen lost from different ferti lization stages in the rice field was 44.1%—54.4%, and the ammonia volatilizati on loss was 25.4%—33.3%. Reducing ammonia loss is an important treatment for im proving N use efficiency.

Kinetic and thermodynamic effects of moisture content and temperature on the ammonia volatilization of soil fertilized with urea

The traditional qualitative analysis of the individual factors on the kinetic and thermodynamic parameters cannot sufficiently reveal the mechanism underlying ammonia volatilization in soil.This study aimed to determine the effects of temperature,moisture content,and their interaction on the kinetic and thermodynamic parameters,which revealed the key control mechanism underlying ammonia volatilization,modified the traditional Arrhenius model,and established a quantitative prediction model of cumulative NH_(3)-N loss(CNL).Laboratory culture experiments were conducted under different temperatures(T)(15℃,20℃,25℃and 35℃)and moisture contents(θ)(60%,80%,and 100%field capacities).Soil ammonia volatilization was also measured every 2 d.Results showed that the effects of individual factors and their interaction on the values of reaction rate(K_(N)),Activation free energy(ΔG),and activation entropy(ΔS)followed the descending order of T>θ>T·θ,whereas those of activation enthalpy(ΔH)and activation degree(lgN)followed the descending order ofθ>T>T·θ.The interaction showed significant effect on K_(N)value and insignificant effect on all the thermodynamic parameters.The effects of water and temperature were mainly observed during the preparatory stage and the most critical transition state stage of the chemical reaction,respectively.Given thatΔH>0,ΔG>0,andΔS>0,ammonia volatilization is found to be an endothermic reaction controlled by enthalpy.The new K_(N)(T)-2 model with the determination coefficient(R^(2))of 0.999 was more accurate than the traditional Arrhenius model with the R^(2)of 0.936.The new NH_(3)(T,θ)model with the mean absolute percentage error(MAPE)of 4.17%was more accurate than the traditional NH_(3)(T)model with the MAPE of 7.11%.These results supplemented the control mechanism underlying ammonia volatilization in soil fertilized with urea and improved the prediction accuracy of CNL.

Nitrogen Cycling and Losses Under Rice-Wheat Rotations with Coated Urea and Urea in the Taihu Lake Region

A lysimeter experiment with undisturbed soil profiles was carried out to study nitrogen cycling and losses in a paddy soil 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.

NH3 Volatilization from Aboveground Plants of Winter Wheat During Late Growing Stages

Ammonia volatilized from aboveground parts of winter wheat was collected with an enclosuregrowth chamber and measured from jointing to maturing stage. The results showed that ammonia releasedfrom unfertilized plants grown in high and low fertility soils remained at low rates of 2.3 and 0.9 μg NH3 40plant-1 h-1 respectively at late filling stage. However, fertilized plants rapidly increased the rates to 43.4 and52.2 μg NH3 40 plant-1 h-1 in the high and low fertility soils, respectively, at the same period. The released a-mount was different in different parts of plants. At filling stage, lower senescing stems and leaves volatilizedmore ammonia than upper parts, i.e. , ears and flag leaves that grew normally, with an average of 1.4 and0.7 μg NH3 20 plant-1 h-1 respectively, strongly suggesting that it was the senile organs that released largeamounts of ammonia. At the grain filling stage, shortage of water supply (drought stress) reduced ammoniavolatilization. The average rate of ammonia released under water stress was 0.9 μg NH3 40 plant-1 h-1 , but 1.2μg NH3 40 plant-1 h-1 with moderate water supply. Application of N together with P fertilizer resulted in ahigher ammonia volatilization than N fertilization alone at the maturing stage. The average rate released was135.3 μg NH3 40 plant-1 h-1 when 0.4 g N and 0.13 g P had been added to per kg soil, while 33.7 μg when0.4 g N added alone. Ammonia volatilization from plants was closely related with plant biomass and N up-take; P fertilization increased plant biomass and N uptake and therefore increased its release.

Ammonia Volatilization from Soils Fertilized with Different Nitrogen Type and Application Method in Germination and Early Seedling Stages from the Radish Field

Ammonia volatilization(AV) from basal fertilizer with different nitrogen(N) types and application methods was investigated by the ventilation method in germination and early seedling stages during radish growth seasons in 2014. Four N fertilizer types, urea(U), ammonium bicarbonate(AB), ammonia sulfate(AS), and controlled urea formaldehyde(CUF) were applied through 5 cm depth placement(I) and 10 cm depth placement(II). The results showed that the N fertilizer type was the main factor that caused AV loss in germination and early seedling stages from the radish field. The highest and the lowest cumulative AV losses in germination and early seedling stages from the radish fields were 33.23 and 11.21 N kg/hm^2 for the treatments of AB+I and CUF+II, respectively, accounting for 60.40 and 26.40% of the N application for each treatment. The 10 cm deep placement of N reduced AV rates and lagged the AV process, and CUF significantly reduced ammonia volatilization. The data showed that the suitable N fertilizer type and application method for basal fertilizer were CUF and deep placement, respectively.Therefore, fertilizing with proper N fertilizer types and methods should be the efficient measures to mitigate AV losses from the radish field and will alleviate environment problems.

Ammonia volatilization and availability of Cu,Zn induced by applications of urea with and without coating in soils

Ammonia volatilization and the distribution of Cu and Zn were investigated in two types of soil treated with coated and uncoated urea.The rate of ammonia volatilization in two weeks after fertilizing with coated urea was 8% in soil 1 (soil derived from river alluvial deposits in Dongting Lake Plain) and 5.15% in soil 2 (red soil derived from quaternary red clay),about half the rates observed when fertilizing with common urea,implying that the hydrolysis speed of the coated urea was lower than for common urea,and that the coated urea can increase nitrogen use efficacy.As for the availability of Cu and Zn,their concentrations decreased in the first week after fertilization,and then increased,which was contrary to the effect of treatment on soil pH.For example,when the pH was 7.99,there was 0.79mg/kg exchangeable Cu and 0.85mg/kg exchangeable Zn in the soil derived from river alluvial deposits in Dongting Lake Plain.However,the concentrations of exchangeable Cu and Zn were generally lower for the common urea treatments than those with the coated urea because the peak pH for the common urea treatment was greater.The concentrations of these elements correlated well with pH in the range 4-8 in second order polynomial fits.

Evaluation of Pathway of Nitrogen Loss in Winter Wheat and Summer Maize Rotation System

The nitrogen loss pathway in winter wheat and summer maize rotation system was studied based on field experimental data. The results showed that nitrogen recovery rate was significantly decreased with nitrogen fertilization rate increased, while residual rate and losses rate had an increasing trend. Accumulated ammonia volatilization loss in winter wheat and summer maize rotation was 12. 8(N0), 22. 0(N120), 33. 0(N240) and 64. 5 kg N ha-1(N360) respectively and rate of ammonia volatilization loss was 3.8, 4.2 and 7. 2 % respectively while urea was mixed with 0 - 10 cm soil or spread before irrigation. Denitrification loss with acetylene-soil core incubation method in winter wheat was lower than 1 kg N ha-1 and rate of denitrification loss was 0. 21 - 0. 26% or trace. Denitrification loss in summer maize was 1 - 14 kg N ha-1 and rate of denitrification loss was 1 - 5 %. The total gaseous loss in winter wheat and summer maize rotation system was less than 10 %, and the main nitrogen fertilizer loss way was leaching below 0 - 100 cm soil profile and accumulated in deeper soil.

Gaseous Loss of Nitrogen from Fertilizers Applied to Wheat on a Calcareous Soil in North China Plain

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 difference 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.

树脂包膜尿素配施普通尿素对直播稻田氨挥发、氮素径流和渗漏损失及产量的影响

为探究树脂包膜尿素与普通尿素配施对直播稻田氮素损失的影响,于2021年开展大田试验,在施氮180 kg·hm^(-2)水平下,设置8个氮肥处理:树脂包膜尿素(基肥)∶普通尿素(分蘖肥)=4∶6(CRF4U6)、6∶4(CRF6U4)、8∶2(CRF8U2),一次性基施树脂包膜尿素(CRF10U0);普通尿素(基肥)∶普通尿素(分蘖肥)=4∶6(C4U6)、6∶4(C6U4)、8∶2(C8U2);以不施氮处理为对照(CK)。结果表明:施树脂包膜尿素处理(CRFU系列)基肥期氨挥发通量峰值显著低于施普通尿素处理(U系列),水稻整个生育期氨挥发损失量以CRF10U0最低,CRF8U2次之,其氨挥发损失率分别为7.35%和8.92%。CRFU系列水稻生育期总氮(TN)径流流失率均显著低于U系列,以CRF10U0最低,CRF8U2次之,其流失率仅为1.69%和2.04%,原因是直播稻田径流主要发生在施基肥后,而CRFU系列基肥期(5月22日、5月26日)径流TN浓度显著低于U系列。直播稻田30 cm处渗漏水中氮素以NH^(+)_(4)-N为主,基肥期CRFU系列30 cm处渗漏水中TN、NH^(+)_(4)-N浓度峰值显著低于U系列,水稻整个生育期氮素渗漏损失量CRFU系列显著低于U系列,以CRF10U0最低,CRF8U2次之,其渗漏淋失率分别为2.90%、3.18%。CRF8U2与C4U6产量显著高于其他处理(CRF10U0除外),而CRF8U2产投比仅比C4U6低4.90%。综合考虑氮素损失、产量和产投比等多方面因素,CRF8U2施肥模式更加贴合直播稻实际生产。

不同施肥方式对再生稻田氨挥发及氮肥利用率的影响

【目的】探究控释尿素和普通尿素配施及控释尿素一次性深施技术对再生稻田氨挥发和氮肥利用率的影响,以期为我国再生稻田增产减排措施的制定提供科学指导。【方法】以水稻品种丰两优香1号和甬优4949为试验材料,设不施氮对照(CK)、常规分次施普通尿素(FFP)、普通尿素组配控释尿素一基一追(CRU+U)和一次性根区10 cm深施控释尿素(CRUR)4个处理。测定不同施肥处理下再生稻田氨挥发变化趋势、两季产量及氮肥利用率。【结果】与FFP处理相比,CRUR和CRU+U处理降低了再生稻生育期内的氨挥发通量,CRUR处理氨挥发损失量和氨挥发损失率分别显著降低77.01%~78.10%和92.17%~95.35%(P<0.05,下同),CRU+U处理的氨挥发损失量和氨挥发损失率分别显著降低53.60%~55.75%和65.45%~66.72%;甬优4949和丰两优香1号的平均氨挥发损失量无显著差异(P>0.05)。与FFP处理相比,CRUR和CRU+U处理显著降低了田面水铵态氮(NH4+-N)和硝态氮(NO3--N)浓度;与FFP处理相比,CRUR处理再生稻头季产量、再生季产量和氮肥吸收利用率分别增加30.00%~30.38%、12.10%~20.28%和84.31%~87.37%,CRU+U处理再生稻头季产量、再生季产量和氮肥吸收利用率分别增加10.00%~16.46%、10.60%~18.84%和35.14%~36.13%;甬优4949的头季和再生季的平均产量分别比丰两优香1号高12.50%和13.11%。相关分析结果表明,再生稻氨挥发通量与田面水的NH4+-N浓度极呈显著正相关(P<0.01)。【结论】与常规分次施普通尿素相比,普通尿素组配控释尿素一基一追和一次性根区10 cm深施控释尿素均能显著降低稻田氨挥发损失,增加再生稻两季产量,提高氮肥利用率,且根区一次性深施控释尿素的增产减排效果优于普通尿素组配控释尿素一基一追施肥处理。

氮肥增效剂对石灰性潮土氨挥发及冬小麦产量的影响

石灰性土壤由于偏碱性的特点容易发生氨挥发,严重的氨挥发会导致氮肥资源的浪费,而且会污染大气环境。在河南省许昌市的石灰性潮土上开展小麦季氮肥增效剂应用效果试验,氮肥用量180 kg/hm^(2),研究4个肥料处理:无化肥氮(CK)、常规尿素(U)、脲酶抑制剂尿素(URI)和硝化抑制剂尿素(NIF)对华北典型石灰性潮土冬小麦整个生育期氨挥发及小麦产量的影响。结果表明,各处理土壤氨挥发速率峰值均出现在小麦播种施肥后第3周,其大小顺序为:U>NIF>URI>CK。U处理下的土壤氨挥发速率峰值比NIF处理和URI处理分别高2.27%和21.84%,NIF处理比URI处理土壤氨挥发速率峰值高19.13%;而小麦整个生育期氨挥发累积量的大小顺序为:NIF>U>URI>CK。整个小麦生育期,3个施氮处理氨挥发损失量均较低,仅为施氮量的1.18%~1.58%。与常规尿素U处理相比,URI处理与NIF处理氨挥发均无显著降低或增加,但NIF比URI显著增加了氨挥发量。与U处理相比,URI处理和NIF处理显著提高小麦的穗数、千粒重和产量,其中URI处理比U处理产量和氮肥利用率分别显著提升14.9%和19.7%,NIF处理分别显著提升25.9%和28.6%。在本研究土壤及施肥管理条件下,虽然硝化抑制剂比脲酶抑制剂促进了氨挥发,但整个冬小麦生育期各处理氨挥发总量都较低,氨挥发量占施肥量的比例均不足2%;硝化抑制剂(CP)尿素在小麦增产中的效益显著高于脲酶抑制剂(NBPT),具有推广应用价值。

南京两种菜地土壤氨挥发的研究

在南京雨花区武警农场和栖霞区东阳科技站先后进行了秋季小青菜和秋冬季大白菜田间试验,研究菜地土壤施用氮肥后的氨挥发及其影响因素,氨挥发采用密闭室间歇密闭通气法测定。结果表明,小青菜试验地的pH为5 .4 ,施肥后土壤pH值也未高于6 .0 ,故氨挥发损失低(<0 .4 % ) ;而在pH为7.7的大白菜试验地上,控释尿素、低氮和高氮3个处理(施氮量分别为N 180、30 0和6 0 0kghm-2 )氨挥发率分别为0 .97%、12 .1%和17 1%。以上结果表明,土壤pH是影响菜地土壤氨挥发的主要因素,降低氮肥用量能明显减少氨挥发,而施用控释尿素是一种有效控制氨挥发损失的措施。大白菜不同施肥期的结果还表明,施尿素后降雨通过降低表层土壤氮的浓度而影响氨挥发,降雨离施肥期越近,雨量越大。

冬小麦/夏玉米轮作体系中氮素的损失途径分析

根据田间试验结果对冬小麦 /夏玉米轮作体系中氮素的损失途径进行了分析。结果表明 ,随施氮量的增加 ,氮肥利用率显著下降 ,而氮肥的损失率和土壤残留率有升高的趋势。以尿素作氮源将肥料混施入 0～ 10cm土壤或撒施后立即灌水的条件下 ,冬小麦 /夏玉米轮作体系中氨挥发的累积损失量分别为每公顷 12 .8(N0 )、2 2 .0(N12 0 )、33.0 (N2 4 0 )和 6 4 .5kgN(N36 0 ) ,氨挥发损失率依次为 3.8%、4 .2 %和 7.2 %。用乙炔抑制 土柱培养法测定的冬小麦生育期氮肥的反硝化损失量每公顷小于 1kgN ,氮肥的硝化 反硝化损失率仅为 0 .2 1%～ 0 .2 6 %或痕量。夏玉米季硝化 反硝化总损失量为每公顷 1～ 14kgN ,相当于当季施氮量的 1%～ 5 %。在北京冬小麦 /夏玉米轮作体系中 ,氮素的气体损失不超过总施氮量的 10 % ,氮肥的主要损失途径是淋洗出 0～ 10 0cm土体 ,在下层土壤中累积。

太湖地区稻田氨挥发及影响因素的研究

应用微气象学方法研究太湖地区水稻三个不同施肥期施用尿素后的氨挥发损失 ,并对其影响因素 (气候、田面水中NH+4 N浓度和作物覆盖等 )的作用进行了分析研究。结果表明 ,水稻施用尿素后的氨挥发损失为各时期施氮量的 18 6 %～ 38 7% ,其中以分蘖肥时期损失最大 ,其次为基肥 ,穗肥氨挥发损失最小。氨挥发损失主要时期是在施肥后 7d内。在水稻不同生长期 ,各因素对氨挥发的影响能力大小并不一样 ,三个施肥期的氨挥发损失通量与施肥后田面水中铵态氮浓度呈显著正相关。

江苏南部地区稻麦两熟土壤中尿素的氨挥发损失

采用连续气流密闭室法研究了江苏南部丘陵地区稻麦两熟农田施用尿素后的氨挥发损失及其年际变化。结果表明 ,不同年份间麦田的氨挥发量 (N)占施氮量的比例变化在 4 0 7%～ 14 8%之间。尿素作水稻基肥时 ,氨挥发量为1 77%～ 5 5 7% ,分蘖期为 10 7%～ 16 % ,而孕穗期为 5 3 %～ 8 6 %。无论是麦田还是稻田 ,施用尿素后 ,年际间氨挥发量相差显著。高温、长日照和低降雨量促进氨挥发。土壤水分含量对麦田的尿素氨挥发的作用可能大于温度对它的影响。稻田高郁闭度和尿素混入土壤均能明显减少氨挥发。

北方冬小麦/夏玉米轮作体系土壤氨挥发的原位测定

采用通气法测定了北方冬小麦 /夏玉米轮作体系田间土壤的原位氨挥发。结果表明 ,与冬小麦施用基肥相比 ,夏玉米追肥后土壤的氨挥发速率很快升高 ,但挥发高峰期持续时间较短 ,最大氨挥发速率亦低于冬小麦。冬小麦拨节期追肥 ,氨挥发速率低且呈波动变化 ,未出现高峰值。从整个生长季节来看 ,冬小麦不施氮和每公顷施氮 1 2 0、2 4 0、36 0 kg时的累计挥发量分别为 4 .4、6 .9、1 3.0、38.4 kg N/hm2 ,夏玉米为 8.4、1 5 .1、2 0 .0、2 6 .1 kg N/hm2。按我国北方冬小麦 /夏玉米播种面积 1 86 4 .4万 hm2 计 ,每年由氨挥发向大气排放的氮素达 2 3.8～ 1 2 0 .2万 t,其中 1 7.2～ 96 .4万 t来自氮肥 ,相当于氮肥投入的 2 .1 %～ 9.5 %。

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。