Ammonia Volatilization and Deriitrification Losses from an Irrigated Maize-Wheat Rotation Field in the North China Plain

Ammonia (NH3) volatilization, denitrification loss, and nitrous oxide (N2O) emission were investigated from an irrigated wheat-maize rotation field on the North China Plain, and the magnitude of gaseous N loss from denitrification and NH3 volatilization was assessed. The micrometeorological gradient diffusion method in conjunction with a Bowen Ratio system was utilized to measure actual NH3 fluxes over a large area, while the acetylene inhibition technique (intact soil cores) was employed for measurement of denitrification losses and N2O emissions. Ammonia volatilization loss was 26.62% of the applied fertilizer nitrogen (N) under maize, while 0.90% and 15.55% were lost from the wheat field at sowing and topdressing, respectively. The differences in NH3 volatilization between different measurement events may be due to differences between the fertilization methods, and to differences in climatic conditions such as soil temperature.Denitrification losses in the fertilized plots were 0.67%-2.87% and 0.31%-0.49% of the applied fertilizer N under maize and wheat after subtracting those of the controls, respectively. Nitrous oxide emissions in the fertilized plots were approximately 0.08%-0.41% and 0.26%-0.34% of the applied fertilizer N over the maize and wheat seasons after subtracting those of the controls, correspondingly. The fertilizer N losses due to NH3 volatilization were markedly higher than those through denitrification and nitrous oxide emissions. These results indicated that NH3 volatilization was an important N transformation in the crop-soil system and was likely to be the major cause of low efficiencies with N fertilizer in the study area. Denitrification was not a very important pathway of N fertilizer loss, but did result in important evolution of the greenhouse gas N2O and the effect of N2O emitted from agricultural fields on environment should not be overlooked.

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.

Translocation and recovery of 15N-labeled N derived from the foliar uptake of 15NH3 by the greenhouse tomato（Lycopersicon esculentum Mill.）

In order to completely evaluate ammonia emission from greenhouse vegetable fields,crop canopy absorption should not be neglected.The foliar uptake of NH3 applied at two growth stages and the subsequent 15N-labeled N translocation to other plant components were investigated under greenhouse conditions using chambers covered with the soil of a tomato field.Treatments comprised three NH3-N application rates(70,140,and 210 mg/plot) using 15N-labeled ammonium sulfate.Plants were harvested immediately after exposure for 24 h,and the total N concentrations and 15N/14 N ratios were determined.With increased NH3 concentration,total 15NH3-N absorption increased considerably,whereas the applied 15NH3-N uptake decreased gradually.The tomato plants absorbed 33-38% and 24-31% of the 15NH3-N generated at the anthesis and fruit growth stages,respectively.A total of 71-80% of the recovered NH3 was observed in the leaves and 20-30% of the recovered NH3 was remobilized to other components.Among them,an average of 10% of the absorbed 15NH3-N was transferred into the tomato fruits.All these results indicated the potential of the tested tomatoes for the foliar uptake of atmospheric 15NH3 and the distribution of 15N-labeled vegetative N among different plant components.The results are of great importance for the complete evaluation of nitrogen use efficiency in the greenhouse tomato fields.

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.

Simulation Study of Diesel Spray Tilt Angle and Ammonia Energy Ratio Effect on Ammonia-Diesel Dual-Fuel Engine Performance

Ammonia-diesel dual fuel(ADDF)engines for transportation applications are an important way to reduce carbon emissions.In order to achieve better combustion of ammonia in diesel engines.A small-bore single-cylinder engine was converted into an ADDF engine with the help of mature computational fluid dynamics(CFD)simulation software to investigate the performance of an engine with a high ammonia energy ratio(AER),and to study the effect of spray tilt angle on ADDF engine.The results showed that the increase in AER reduced nitric oxide(NO)and nitrogen dioxide(NO2)emissions but increased nitrous oxide(N2O)and unburned ammonia emissions.AER in the range of 50%-70%achieved lower greenhouse gases(GHG)emissions than the pure diesel mode.Relative to the pure diesel mode,when the AER was 60%,the indicated thermal efficiency(ITE)was increased by 0.2%and the GHG emissions were decreased by 22.3%,but carbon monoxide(CO)and Hydrocarbon(HC)emissions were increased.Increasing the in-cylinder combustion temperature or high-temperature region range of the ADDF engine could reduce GHG emissions.At an AER of 60%,an increase in the spray tilt angle helped the ammonia combustion in the residual gap to reduce the unburned ammonia emissions.Compared to the pure diesel mode with a spray tilt angle of 75°,an AER of 60%with a spray tilt angle of 77.5°improved the ITE by 1.5%,and reduced theGHGemissions by 25.7%.Adjusting the spray tilt angle of theADDFengine also reducedCOandHCemissions.This is an effective way to improve ADDF engine performance by adjusting the spray tilt angle.

Model Research on the Effect of Surface Film on Ammonia Volatilization from Rice Field

Pan and field experiments were conducted to investigate the effect of surface film on ammonia volatilization from water and paddy soil. The results showed that the addition of the surface film on floodwater reduced the rate of ammonia volatilization, however, the reduction of the latter varied greatly with its rates of addition. Jayaweera-Mikkelsen ammonia volatilization model with the introduction of a parameter Kf, a relative measure of the resistance of the surface film on ammonia volatilization, was used to elucidate the effectiveness of the surface film on lowering ammonia volatilization. The Kf value was calculated from the results ob-

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

Ammonia volatilization loss and ^15N balance were studied in a rice field at three different stages after urea application in Taihu Lake area with a micrometeorological technique. Factors such as climate and the NH4^＋-N concentration 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 intermediate 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 field 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 rather low, only about 12%. The total amount of nitrogen lost from different fertilization stages in the rice field was 44.1%-54.4%, and the ammonia volatilization loss was 25.4%-33.3%. Reducing ammonia loss is an important treatment for improving N use efficiency.

Ammonia Volatilization and Nitrogen Utilization Efficiency in Response to Urea Application in Rice Fields of the Taihu Lake Region,China

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 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 fert…

Gaseous Loss of Nitrogen from Fertilizers Applied to a Paddy Soil in Southeastern China

Total nitrogen (N) loss and ammonia volatilization from urea applied to flooded rice grown on a paddy soil in Zhejiang Province were measured by 15N balance and micro-meteorological methods, respectively. Floodwater properties and ammonia loss from the circular plot were compared with those from the microplots. And the effectiveness of urease inhibitor, NBPT [N-(n-butyl) thiophosphonc triamide], was also tested Results showed that the total losses from urea broadcast and incorporated at transplanting (basal dressing) were similar with those from urea broadcast 12 days after transplanting (top-dressing) (51.5% and 48%, respectively, of applied N), and ammonia losses were low, the corresponding figures were 10.8% and 7.0% of applied N, respectively. Thus, denitrification was a much more important pathway of nitrogen loss than ammonia volatilization under the particular conditions. Addition of NBPT retarded urea hydrolysis, reduced pHs and ammoniacal nitrogen concentrations of floodwater for either the application of urea as basal or as top-dressing, but these effects were not translated into the reduction of total nitrogen loss. Floodwater pHs and ammonia loss in the microplots were apparently lower than those in the circular plot from urea applied as basal dressing; however, such differences were not found when urea was top-dressed. The frequently raining days occurred after top-dressing may be responsible for the insignificant effect of plot size on floodwater pHs and ammonia volatilization. It seems that the effects of plot size on floodwater properties and ammonia loss mainly depend on weather conditions, in addition to the height and leaf area index of the crop.

Evaluation of Methods for Control of Ammonia Volatilization from Surface-Applied Nitrogen Fertilizers to Sugarcane Trash in North Queensland

Micrometeorological and microplot experiments were conducted in the field of freshly harvested green cane in Queensland, Australia. Results showed that high ammonia loss of fertilizer N could occur under relatively dry conditions when urea or commercial product of mixture of urea and muriate of potash were applied to the surface of sugarcane trash. The moisture content in the trash and the pH of fertilizer were two important factors controlling the processes of urea hydrolysis and ammonia volatilization. Most of the N in the soil was transformed to the nitrate+ nitrite from after 70 days of fertilizer application. No significant leaching was found. Urea-free N fertilizers had higher N recoveries compared to urea-containing fertilizers. .

Effects of different long-term crop straw management practices on ammonia volatilization from subtropical calcareous agricultural soil

Ammonia(NH3)volatilized from agricultural production and its secondary aerosols contribute greatly to air pollution.Different long-term crop straw management practices may significantly affect the soil fertility and soil nitrogen cycle,however,the effect on NH3 volatilization has not been well studied.Therefore,a one-year field experiment was conducted to evaluate the effect of straw incorporation on NH3 volatilization from subtropical calcareous agricultural soil from a longterm perspective,including four treatments:synthetic fertilizer(CK);synthetic fertilizer incorporation with 100%or 50%of the previous season’s crop straw(SI1 and SI2,respectively);and synthetic fertilizer incorporation with 50%burned crop straw(SI2B).Soil NH3 volatilizations were monitored through a wheat–maize rotation year by using a dynamic chamber method.The results demonstrated that NH3 volatilization primarily occurred within 38 days and 7–10 days following nitrogen fertilization events for the wheat and maize seasons,respectively.Different crop straw management practices mainly impacted the NH3 flux of the basal fertilization rather than the topdressing fertilization;long-term crop straw incorporation effectively lowered NH3 loss(35.1%for SI1 and 16.1%for SI2 compared to CK;and the inhibiting effect increased with increasing straw amount,possibly contributed by the high straw carbon/nitrogen ratio,and enhanced microbial activity,which contributed to inorganic nitrogen immobilization and lower ammonium content in the topsoil.However,SI2B significantly increased(29.9%)the annual NH3 flux compared with SI2,indicating that long-term 100%straw incorporation could be a promising straw management practice for mitigating NH3 loss and increasing soil fertility.

Nitrogen mobility,ammonia volatilization,and estimated leaching loss from long-term manure incorporation in red soil

Nitrogen（N） loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practices. The aim of this study was to evaluate the fate of N fertilizers applied to acidic red soil（Ferralic Cambisol） after 19 years of mineral（synthetic） and manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined： control（CK）, chemical nitrogen and potash fertilizer（NK）, chemical nitrogen and phosphorus fertilizer（NP）, chemical nitrogen, phosphorus and potash fertilizer（NPK） and the NPK with manure（NPKM, 70% N from manure）. Based on the soil total N storage change in 0–100 cm depth, ammonia（NH_3） volatilization, nitrous oxide（N_2O） emission, N plant uptake, and the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer treatments（NK, NP and NPK） showed increased nitrate（NO_3~–） concentration with increasing soil depth, indicating higher leaching potential. However, total NH_3 volatilization loss was much higher in the NPKM（19.7%） than other mineral fertilizer treatments（≤4.2%）. The N_2O emissions were generally low（0.2–0.9%, the highest from the NPKM）. Total gaseous loss accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH_3 volatilization, which could be reduced by improving the application method. This study confirms that manure incorporationis an essential strategy in N fertilization management in upland red soil cropping system.

Dry deposition of ammonia around paddy fields in the subtropical hilly area in southern China

This study measured the ammonia(NH3)concentration and dry deposition within 100 m around paddy fields(0.6 ha)with double rice cropping in the subtropical hilly area in southern China,with the aims to quantify the dry deposition of NH3 around the emission source and to clarify its temporal and spatial variability.The results showed that high NH3 concentrations were found during the 15 d after nitrogen(N)fertilizer application at downwind sites within 100maround the paddy fields,and the NH3 concentrations were 12–62,2.8–7.3,13–38,and 4.9–36μg N m−3 during the 15 d after basal fertilizer application and topdressing in the early rice season and after basal fertilizer application and topdressing in the late rice season,respectively.The NH3 concentrations were relatively low(1.5–-3.8μg N m−3)during other periods of the rice season at the downwind sites,which indicated that N fertilizer application in paddy fields highly affected the NH3 concentration at downwind sites.The NH3 concentrations at the downwind sites decreased significantly with the increase in distance from the paddy fields.The total NH3 dry deposition around 100 m of the paddy fields accounted for approximately 79%and 81%of the emitted NH3 from the paddy fields in the early and late rice seasons,respectively.The results indicate that dry deposition of NH3 around emission sources may be an important way to remove the NH3 volatilized from croplands in this subtropical hilly area.

减氮施炭对温室膜下滴灌黄瓜土壤呼吸和氮素气态损失的影响

为降低温室蔬菜过量施氮的不利影响,明确减氮施炭条件下温室膜下滴灌黄瓜土壤呼吸和氮素气态排放特征,以不覆膜不施炭(CK)为对照,设置覆膜(M)、覆膜施炭(MB)、覆膜施炭减氮(MBN_(80%))共4个处理,对覆膜条件下减氮施炭处理对黄瓜产量、耗水量、土壤养分动态、土壤呼吸、N_(2)O排放和氨挥发的影响进行探讨。结果表明:与CK相比,M可降低温室膜下滴灌黄瓜全生育期耗水量20.95%,提高水分利用效率41.03%,降低0~20 cm表层土铵态氮48.12%,降低全生育期氨挥发32.35%、N_(2)O排放量14.34%和CO_(2)排放量12.68%(<0.05)。施炭后,与CK相比,MB可降低耗水量28.37%,提高水分利用效率55.60%,降低表层土铵态氮30.0%,提升硝态氮12.37%,有机质56.28%,降低氨挥发36.68%、N_(2)O排放18.64%,但却显著增大了CO_(2)排放4.66%(p<0.05)。同M对比,MB可在M基础上,进一步提升表层土有机质和铵态氮含量,降低氨挥发,但促进了CO_(2)排放。覆膜施炭减氮20%后,与CK相比,MBN_(80%)可增产25.47%,降低耗水量32.43%,提升水分生产率72.67%,降低表层土铵态氮56.33%,增加有机质51.72%,降低氨挥发40.48%、N_(2)O排放20.79%(p<0.05)。CK全生育期全球增温潜势(global warming potential,GWP)和活性氮排放分别为13.57 t·CO_(2)-eq·hm^(-2)和6.54 kg·hm^(-2),M可显著降低GWP(14.15%)和活性氮排放(27.37%);在M基础上施炭,将进一步降低活性氮排放,但导致GWP显著增大;而在MB基础上减氮20%,可同时显著降低GWP和活性氮排放(p<0.05)。与CK相比,MBN80%在通过施炭20 t·hm^(-2),减氮20%条件下,实现增产25.47%,降低耗水量32.43%,增加有机质51.72%,增加收入17.52%,降低活性氮排放35.32%和GWP 2.28%,也可在MB的基础上,进一步实现增产,降低氨挥发,并破解M和MB处理CO_(2)排放增大的问题(p<0.05)。研究揭示了减氮施炭条件下温室膜下滴灌黄瓜土壤呼吸和氮素气态排放特征,为实现温室蔬菜节水增产固碳减排提供理论依据和技术支撑。

玉米基肥期农田土壤氨挥发量与近地表氨浓度相关性研究

农田氨排放量与近地表氨浓度密切相关,但两者能否相互转换还缺乏系统研究。基于此,以近地表氨浓度经典方法(被动法)为主要使用方法,以传统海绵法为对照方法,在豫南砂姜黑土开展5种典型施肥处理玉米季基肥期氨排放量与近地表氨浓度的相关性研究。结果发现,不同施肥处理的氨挥发峰值均出现在施肥后的2-4 d,第5天开始显著降低,第8天之后基本与对照无明显差异;不同处理的氨累计排放量差别较大,排序为TR>OPT>SOPT>HK>CK,累计排放量分别为7.68、5.48、3.37、2.78和0.22 kg·hm^(-2);同时发现,不同施肥处理近地表氨浓度也有相同趋势,峰值同样出现在施肥后的2-4 d,第5天开始显著降低,平均氨质量浓度排序为TR>OPT>SOPT>HK>CK,均值分别为17.5、11.6、10.7、8.21和1.70μg·m^(-3)。线性相关性分析表明,施肥后前8 d不同施肥处理的氨挥发量与近地表氨浓度的线性相关性较强,而8 d之后两者的相关性较弱,说明近地表氨浓度和农田氨挥发量的相关性与农田氨挥发量的高低有关。除此之外,不同方法中被动法对低施氮量和缓释肥的估算优于排放因子法,而排放因子法对高施肥条件下氨挥发量的估算优于被动法。整体而言,被动方法估算氨挥发量的相对误差介于-15.9%-17.5%之间,排放因子法相对误差介于-54.3%-81.8%之间,被动方法明显具备更高的估算精度。以上结果说明,被动方法可以潜在替代传统氨监测方法估算大区域农田氨挥发量,但估算精度主要集中在高氨排放期。

蝇蛆预处理及辅料添加对鸡粪堆肥氨挥发和温室气体排放的影响

为明确蝇蛆预处理及辅料添加对鸡粪堆肥过程中NH3挥发及温室气体排放的影响,本研究分别将风化褐煤、厨余垃圾、蘑菇渣与鸡粪混合,在进行蝇蛆预处理后堆肥,研究试验过程中NH3挥发和温室气体的排放规律。试验设置8个处理,分别为对照组(无蝇蛆预处理):纯鸡粪(CK1)、30%风化褐煤+70%鸡粪(CK2)、30%厨余垃圾+70%鸡粪(CK3)、30%蘑菇渣+70%鸡粪(CK4);试验组(蝇蛆预处理):纯鸡粪(T1)、30%风化褐煤+70%鸡粪(T2)、30%厨余垃圾+70%鸡粪(T3)、30%蘑菇渣+70%鸡粪(T4)。结果表明:蝇蛆预处理能够延长堆肥高温期,≥50℃天数均达到10 d以上,相比CK1增加5~9 d;在整个试验期间试验组NH3挥发集中在堆肥第2天,试验组NH3累积排放量显著低于对照组,降幅达到42.7%~61.1%,菇渣添加处理的NH3累积排放量在对照组中最低;风化褐煤的添加能够显著降低N2O排放,T2相比于T1降低84.2%,CK2相比于CK1降低51.7%。蝇蛆预处理能够显著降低CO_(2)排放当量,相比CK1降低32.1%~73.2%,其中,T4的CO_(2)排放当量最低。研究表明,蝇蛆预处理能够提高堆肥温度、延长堆肥高温期、显著降低NH3排放和CO_(2)排放当量,若从堆肥温度及CO_(2)排放当量方面考虑蝇蛆预处理和菇渣组合为最优处理。

灌溉量和氮肥增效剂对夏玉米产量及水肥利用的影响

为探究水分和氮肥增效剂对夏玉米生长及水肥利用的综合影响,通过设置40 mm(W1)和60 mm(W2)两个灌水水平下不施氮肥(N0)、施用氮肥(U)、氮肥+硝化抑制剂(U+DCD)、氮肥+脲酶抑制剂(U+NBPT)、氮肥+双效抑制剂(U+N+D)5种氮肥施用措施,开展夏玉米田间试验。结果表明:相较于施用氮肥处理,氮肥配施增效剂可以显著提高夏玉米产量、成熟期地上生物量、净收益、水分利用效率和氮肥偏生产力,增幅分别为5.92%~13.82%、5.85%~18.07%、11.12%~24.30%、12.35%~41.83%和5.93%~13.80%,其中氮肥配施双效抑制剂效果较优;氮肥配施脲酶抑制剂和双效抑制剂可以降低夏玉米农田土壤氨挥发累积量和成熟期土壤硝态氮残留量,前者效果最优。相比于W1,W2水平下氮肥配施双效抑制剂处理玉米产量、成熟期地上生物量、净收益、水分利用效率和氮肥偏生产力分别提高10.54%、15.51%、19.40%、20.31%和27.36%;氮肥配施脲酶抑制剂处理农田土壤氨挥发累积量和硝态氮残留量分别降低11.33%和48.46%。综合考虑夏玉米施肥灌水方案的经济效益、环境效益、水肥利用效率和玉米植株生长,构建模糊综合评价体系,得到最优处理为灌水量60 mm下氮肥配施双效抑制剂。

不同粪肥与黄腐酸配施对设施菜地NH3挥发及蔬菜产量的影响

为探究不同粪肥与黄腐酸配施对设施菜地NH3挥发及蔬菜产量的影响。采用小区试验的方法,共进行了2季上海青栽培试验。第1季设置了猪粪(P_(30)、P_(15)、P_(9))分别为30、15、9 t/hm^(2);鸡粪(C_(5)、C_(3))分别为5、3 t/hm^(2);羊粪(S_(11)、S_(6))分别为11、6 t/hm^(2);不施肥对照(CK)。在第1季试验的基础上开展了第2季试验,利用通气法采集NH_(3),粪肥添加处理均为等氮添加,猪粪、鸡粪、羊粪分别为31.9、25.4、31.3 t/hm^(2),设置了黄腐酸(H)、猪粪+黄腐酸(P_(31.9)H)、猪粪(P_(31.9))、鸡粪+黄腐酸(C_(25.4)H)、鸡粪(C_(25.4))、羊粪+黄腐酸(S_(31.3)H)、羊粪(S_(31.3)),不施肥对照(CK),2季试验的处理分别为猪粪30+黄腐酸(P_(30)-H)、猪粪15+猪粪31.9+黄腐酸(P_(15)-P_(31.9)H)、猪粪9+猪粪31.9(P_(9)-P_(31.9))、鸡粪5+鸡粪25.4+黄腐酸(C_(5)-C_(25.4)H)、鸡粪3+鸡粪25.4(C_(3)-C_(25.4)),羊粪11+羊粪31.3+黄腐酸(S_(11)-S_(31.3)H)、羊粪6+羊粪31.3(S_(6)-S_(31.3)),共计7个处理和不施肥对照(CK),监测了不同肥料施加下土壤NH3挥发速率、NH3累积挥发量、蔬菜产量及相关环境因子的变化。结果表明:高NH3挥发速率主要集中在施肥后的1~3 d,单施粪肥条件下,NH_(3)累积挥发量表现为P_(9)-P_(31.9)>(C_(3)-C_(25.4)≈S_(6)-S_(31.3)),粪肥配施黄腐酸条件下,NH3累积挥发量表现为C_(5)-C_(25.4)H>S_(11)-S_(31.3)H>P_(15)-P_(31.9)H;在产量方面,羊粪、猪粪的增产效果要优于鸡粪,羊粪配施黄腐酸的增产效果最好,为27.48 t/hm^(2);在环境因子方面,土壤铵态氮、硝态氮含量与土壤NH_(3)挥发呈显著正相关(分别为P<0.001、P<0.05)。粪肥配施黄腐酸具有降低土壤NH_(3)挥发及增加蔬菜产量的趋势,综合考虑蔬菜产量及NH3累积挥发量,认为羊粪配施黄腐酸的效果最优。