Phenotypic and genotypic heterogeneity among closely related soil-borne N2 - and N2 O-producing Bacillus isolates harboring the nosZ gene

Little is known about the genetic and phenotypic diversity of Gram-positive denitrifying bacteria. We compared the production of gaseous denitrification products for 14 closely related Bacillus soil isolates at pH 6 and 7 during 48-h batch incubations using a robotic gas-sampling apparatus. Primers targeting the nosZ gene encoding the nitrous oxide reductase were designed to confirm the presence of this gene in the isolates. The variation in the production of gaseous nitrogen products was compared with the genetic variation based on 16S rRNA gene sequences, genomic fingerprinting and nosZ sequences. The nosZ gene was detected in all isolates and all produced N(2) as the dominant end product at pH 7. Production of gaseous nitrogen products was more variable at pH 6, with different levels of NO and N(2) O production among the isolates, although minimal variation was observed among the 16S rRNA and nosZ gene sequences. One isolate was more divergent from the others based on genomic fingerprinting, and had two different nosZ gene copies, which coincided with the highest production of N(2) at pH 7 and the lack of intermediates at pH 6. Overall, our analysis suggests that genetic variation plays a role in the variation in N(2) O and N(2) production, but the variation in activity caused by acidification can be substantially greater than genotypic variation among closely related Bacillus.     

Gaseous nitrogen losses from a soilless culture system in the greenhouse

Gaseous nitrogen losses from a closed-loop rockwool system were investigated during the vegetative growth and the stem fruit stage of cucumbers. On average 12.4% of the N input were released in form of N₂O and N₂. This was equivalent to a mean emission rate of 0.62 kg nitrogen per hectare greenhouse area and day. The highest emission rates occurred during the stem fruit development as an increased root decay and an intensive substrate respiration came on. The proportion of N₂O in the gaseous nitrogen losses decreased with increasing N₂O+N₂ evolution. On average it amounted to 9.6%.A comparison of different cucumber crops during the season showed that the gaseous nitrogen losses were nearly twice as high in the summer as in the autumn. Thus it proceeded almost parallel to the plant growth which also doubled. Furthermore, an effect of the substrate temperature is conceivable, since it was 3–4°C higher in the radiation-rich summer-time.With increasing root density in the substrate gaseous nitrogen losses increased while the N₂O/N₂ ratio declined. Possible reasons for this were a greater rhizodeposition of easily decomposable organic substances, an accelerated oxygen consumption by root respiration and a high density of microorganisms in close vicinity to the roots. The growth of green algae on the substrate surface stimulated the production of N₂O.     

Effect of N concentration and N source on root colonization by Pseudomonas fluorescens 2-79RLI

Wheat (Triticum aestivum L.) was grown in nutrient solution with low or high N supply (NH₄NO₃ as N source). To further evaluate the influence of N form and its interaction with the nutrient solution pH, wheat plants were grown with NH ₄ ⁺ or NO ₃ ^- either in an conventional nutrient solution or in a nutrient solution in which the pH was maintained at pH 6.5 using a pH-stat system. The nutrient solution was inoculated with Pseudomonas fluorescens 2-79RLI, a genetically modified bacterium that contains lux genes activated by a ribosomal promoter. Cell numbers and physiological status of P. fluorescens 2-79RLI (length of the lag phase of bioluminescence) in the rhizosphere were determined at the root tip and in the lateral root zone. Nitrogen deficiency decreased both plant growth and root colonization by P. fluorescens 2-79RLI at the root tip while it had no effect on root colonization in the lateral root zone. The physiological status of P. fluorescens 2-79RLI was not affected by nitrogen deficiency. Ammonium nutrition increased root colonization by P. fluorescens 2-79RLI at the root tip and in the lateral root zone when the pH of the nutrient solution was allowed to change according to the N form provided. Under these conditions, the physiological status of P. fluorescens 2-79RLI was higher in the lateral root zone than at the root tip. In contrast, N source had no effect on root colonization or physiological status of P. fluorescens 2-79RLI in the nutrient solution maintained at pH 6.5. It is concluded that the stimulation of root colonization by NH ₄ ⁺ in the nutrient solution, not maintained at a constant pH, may be due to increased leakage of solutes into the rhizosphere as a result of impaired exudate retention by high H⁺ concentration in the rhizosphere or the apoplast. This revised version was published online in June 2006 with corrections to the Cover Date.     

Denitrifying Bacteria in the Earthworm Gastrointestinal Tract and In Vivo Emission of Nitrous Oxide (N(inf2)O) by Earthworms

Earthworms (Lumbricus rubellus and Octolasium lacteum) and gut homogenates did not produce CH(inf4), and methanogens were not readily culturable from gut material. In contrast, the numbers of culturable denitrifiers averaged 7 x 10(sup7) and 9 x 10(sup6) per g (dry weight) of gut material for L. rubellus and O. lacteum, respectively; these values were 256- and 35-fold larger than the numbers of culturable denitrifiers in the soil from which the earthworms were obtained. Anaerobically incubated earthworm gut homogenates supplemented with nitrate produced N(inf2)O at rates exceeding that of soil homogenates. Furthermore, living earthworms emitted N(inf2)O under aerobic conditions, and N(inf2)O emission was stimulated by acetylene. For earthworms collected from a mildly acidic (pH 6) beech forest soil, the rates of N(inf2)O emission for earthworms and soil averaged 884 and 2 pmol per h per g (fresh weight), respectively. In contrast, for earthworms collected from a more acidic (pH 4.6) oak-beech forest soil, N(inf2)O emission by earthworms and soil averaged 145 and 45 pmol per h per g (fresh weight), respectively. Based on the extrapolation of this data, earthworms accounted for an estimated 16 and 0.25% of the total N(inf2)O produced at the stand level of these beech and oak-beech forest soils, respectively.     

Simultaneous quantification of N2, NH3 and N2O emissions from a flooded paddy field under different N fertilization regimes

Gaseous nitrogen (N) emissions, especially emissions of dinitrogen (N₂) and ammonia (NH₃), have long been considered as the major pathways of N loss from flooded rice paddies. However, no studies have simultaneously evaluated the overall response of gaseous N losses to improved N fertilization practices due to the difficulties to directly measure N₂ emissions from paddy soils. We simultaneously quantified emissions of N₂ (using membrane inlet mass spectrometry), NH₃ and nitrous oxide (N₂O) from a flooded paddy field in southern China over an entire rice‐growing season. Our field experiment included three treatments: a control treatment (no N addition) and two N fertilizer (220 kg N/ha) application methods, the traditional surface application of N fertilizer and the incorporation of N fertilizer into the soil. Our results show that over the rice‐growing season, the cumulative gaseous N losses from the surface application treatment accounted for 13.5% (N₂), 19.1% (NH₃), 0.2% (N₂O) and 32.8% (total gaseous N loss) of the applied N fertilizer. Compared with the surface application treatment, the incorporation of N fertilizer into the soil decreased the emissions of NH₃, N₂ and N₂O by 14.2%, 13.3% and 42.5%, respectively. Overall, the incorporation of N fertilizer into the soil significantly reduced the total gaseous N loss by 13.8%, improved the fertilizer N use efficiency by 14.4%, increased the rice yield by 13.9% and reduced the gaseous N loss intensity (gaseous N loss/rice yield) by 24.3%. Our results indicate that the incorporation of N fertilizer into the soil is an effective agricultural management practice in ensuring food security and environmental sustainability in flooded paddy ecosystems.     

The dynamics of nitrous oxide emission from the use of mineral fertilizers in Russia

The intensity of nitrous oxide (N2O) emission was considered based on literature data on the single input of mineral N (nitrogen) fertilizers into different agricultural soil types in Russia. Ambient environmental factors exert a combined effect on the process of gaseous nitrogen formation from fertilizers applied. To reduce the uncertainty of estimates as much as possible, only experimental results obtained under conditions similar to natural were selected for the assessments. Mineral nitric fertilizers were applied to soil at a rate of 40 to 75 kg/ha and the N2O emissions were measured for approximately 140 days. Daily average emission values varied from 0.08 to 0.45% of fertilizer nitrogen. Correspondingly, 1.26 and 2.38% of fertilizer nitrogen were emitted as N2O from chernozems and soddy podzols. In 1990, the use of fertilizers in Russian agricultural practices for 53 Gg N2O-N, which equates to approximately 6.1% of global nitrous oxide emissions from nitric fertilizers. Later, the emission dropped because of a decrease in the input of nitric fertilizers to agricultural crops, and in 1998, it constituted just 20.5% of the 1990 level. In the period from 2008 to 2012, the nitrous oxide emission is expected to vary from 0.5 to 65.0 Gg N2O-N due to possible changes in national agricultural development. In the most likely scenario, the use of mineral fertilizers in Russia will account for approximately 34 to 40 Gg N2O-N emissions annually from 2008-2012.     

N(2) fixation by bacteria associated with maize roots at a low partial o(2) pressure

Nitrogen fixation by bacteria associated with roots of intact maize plants was measured by exposing the roots to N(2) at a partial O(2) pressure (pO(2)) of 2 or 10 kPa. The plants were grown in a mixture of Weswood soil and sand and then transferred to plastic cylinders containing an N-free plant nutrient solution. The solution was sparged continuously with a mixture of air and N(2) at a pO(2) of 2 or 10 kPa. Acetylene reduction was measured after the roots were exposed to the low pO(2) overnight. The air-N(2) atmosphere in the cylinders was then replaced with an O(2)-He atmosphere at the same pO(2), and the roots were exposed to 20 kPa of N(2) for 20 to 22 h. Incorporation of N into the roots was 200 times greater at 2 kPa of O(2) than at 10 kPa of O(2). Adding l-malate (1 g of C liter) to the nutrient solution increased root-associated nitrogenase activity, producing a strong N label which could be traced into the shoots. Fixed N was detected in the shoots within 5 days after the plants were returned to unfertilized soil. In a similar experiment with undisturbed plants grown in fritted clay, movement of fixed N into the shoots was evident within 4 days after the roots were exposed to N(2) at 2 kPa of O(2). Inoculation with Azospirillum lipoferum yielded no significant differences in shoot dry weight, total nitrogen content, percent nitrogen, or N enrichment of plant tissues. Inoculated plants did exhibit greater root dry weight than uninoculated plants, however.     

Decreased N2O reduction by low soil pH causes high N2O emissions in a riparian ecosystem

Quantification of harmful nitrous oxide (N(2)O) emissions from soils is essential for mitigation measures. An important N(2)O producing and reducing process in soils is denitrification, which shows deceased rates at low pH. No clear relationship between N(2)O emissions and soil pH has yet been established because also the relative contribution of N(2)O as the denitrification end product decreases with pH. Our aim was to show the net effect of soil pH on N(2)O production and emission. Therefore, experiments were designed to investigate the effects of pH on NO(3)(-) reduction, N(2)O production and reduction and N(2) production in incubations with pH values set between 4 and 7. Furthermore, field measurements of soil pH and N(2)O emissions were carried out. In incubations, NO(3)(-) reduction and N(2) production rates increased with pH and net N(2)O production rate was highest at pH 5. N(2)O reduction to N(2) was halted until NO(3)(-) was depleted at low pH values, resulting in a built up of N(2)O. As a consequence, N(2)O:N(2) production ratio decreased exponentially with pH. N(2)O reduction appeared therefore more important than N(2)O production in explaining net N(2)O production rates. In the field, a negative exponential relationship for soil pH against N(2)O emissions was observed. Soil pH could therefore be used as a predictive tool for average N(2)O emissions in the studied ecosystem. The occurrence of low pH spots may explain N(2)O emission hotspot occurrence. Future studies should focus on the mechanism behind small scale soil pH variability and the effect of manipulating the pH of soils.     

过量施肥对设施菜田土壤菌群结构及N2O产生的影响

【背景】N_2O是一种很强的温室气体,其温室效应强度大约是CO_2的265倍。土壤氮肥施加量是影响N_2O排放的重要因素,而厌氧条件下微生物反硝化则是N_2O产生的重要途径。【目的】研究过量施肥条件下蔬菜大棚土壤菌群结构变化及其对N_2O气体排放的影响。【方法】利用自动化培养与实时气体检测系统(Robot)监测土壤厌氧培养过程中N_2O和N_2排放通量,比较过量施肥和减氮施肥模式下土壤N_2O排放模式的差异。通过Illumina二代测序平台对这2种不同施肥处理的土壤微生物群落进行高通量测序,研究不同施肥量对土壤菌群组成的影响。【结果】过量施肥土壤中硝酸盐的含量大约是减氮施肥土壤的2倍,通过添加硝酸盐使2种土壤的硝酸盐含量均为60 mg/kg或为200 mg/kg时,过量施肥土壤在厌氧培养前期N_2O气体的产生量及产生速度都明显高于减氮施肥土壤。另外,过量施肥导致土壤菌群结构发生显著改变,并且降低了土壤微生物的多样性。相对于减氮施肥,过量施肥方式富集了Rhodanobacter属的微生物。PICRUSt预测结果显示,传统施肥没有显著改变反硝化功能基因相对丰度。【结论】长期过量氮肥施用显著增加了土壤N_2O的排放,可能原因是施肥改变了包括氮转化相关微生物在内的土壤菌群组成,从而影响了土壤N_2O气体的形成与还原过程。     

N and P Cycling in Tanzanian Humid Savanna: Influence of Herbivores, Fire, and N2-Fixation

Availabilities of nitrogen (N) and phosphorus (P) have a strong influence on plant growth and the species composition of savannas, but it is not clear how these availabilities depend on factors such as fire, N₂-fixation, and activities of wild herbivores and cattle. We quantified soil N and P availabilities in various ways (extractable pools, mineralization, resin adsorption) along vegetation gradients within a recently abandoned cattle ranch and a former game reserve in Tanzania (both areas now part of the Saadani National Park). We also assessed annual N and P balances to evaluate how long-term availabilities of N and P are affected by large herbivores, symbiotic N₂-fixation, and fire. The results show that cattle ranching led to a spatial re-distribution of nutrients, with the local accumulation of P being stronger and more persistent than that of N. In the former game reserve, intensively grazed patches of short grass tended to have elevated soil N and P availabilities; however, because quantities of nutrients removed through grazing exceeded returns in dung and urine, the nutrient balances of these patches were negative. In dense Acacia stands, N₂-fixation increased N availability and caused a net annual N input. Fire was the major cause for nutrient losses from tallgrass savanna, and estimated N inputs from the atmosphere and symbiotic N₂-fixation were insufficient to compensate for these losses. Our results call into question the common assumption that N budgets in annually burned savanna are balanced; rather, these ecosystems are a mosaic of patches with both N enrichment and impoverishment, which vary according to the vegetation type.     

Contributions of Autotrophic and Heterotrophic Nitrifiers to Soil NO and N(2)O Emissions

Soil emission of gaseous N oxides during nitrification of ammonium represents loss of an available plant nutrient and has an important impact on the chemistry of the atmosphere. We used selective inhibitors and a glucose amendment in a factorial design to determine the relative contributions of autotrophic ammonium oxidizers, autotrophic nitrite oxidizers, and heterotrophic nitrifiers to nitric oxide (NO) and nitrous oxide (N(2)O) emissions from aerobically incubated soil following the addition of 160 mg of N as ammonium sulfate kg. Without added C, peak NO emissions of 4 mug of N kg h were increased to 15 mug of N kg h by the addition of sodium chlorate, a nitrite oxidation inhibitor, but were reduced to 0.01 mug of N kg h in the presence of nitrapyrin [2-chloro-6-(trichloromethyl)-pyridine], an inhibitor of autotrophic ammonium oxidation. Carbon-amended soils had somewhat higher NO emission rates from these three treatments (6, 18, and 0.1 mug of N kg h after treatment with glucose, sodium chlorate, or nitrapyrin, respectively) until the glucose was exhausted but lower rates during the remainder of the incubation. Nitrous oxide emission levels exhibited trends similar to those observed for NO but were about 20 times lower. Periodic soil chemical analyses showed no increase in the nitrate concentration of soil treated with sodium chlorate until after the period of peak NO and N(2)O emissions; the nitrate concentration of soil treated with nitrapyrin remained unchanged throughout the incubation. These results suggest that chemoautotrophic ammonium-oxidizing bacteria are the predominant source of NO and N(2)O produced during nitrification in soil.     

全球森林土壤N2O排放通量的影响因子

森林生态系统在全球变暖格局下的地位和作用,尤其是土壤氮库对大气氮沉降增加的响应逐渐成为全球变化研究的热点。本文通过对已有文献资料的调研和整理,分析了1984—2009年间全球38个森林土壤N2O排放通量的野外原位观测结果的分布特征,评估了森林土壤N2O年排放累积通量对大气氮素沉降量和水热条件等因子变化的响应。结果表明,全球森林土壤N2O排放通量的平均值为0.47kgN·hm-2·a-1,而且土壤N2O释放通量随着纬度增加逐渐降低。作为一个复杂的生态过程,土壤N2O累积释放量同样受到年均温、年降水量以及土壤属性的显著影响。其中全球森林土壤N2O释放温度敏感性系数(Q10值)约为1.5。另外,森林土壤N2O排放通量也随着氮沉降量的增加而显著增大,大气氮沉降量可解释土壤N2O排放通量在不同区域之间53%的差异;土壤pH、年均温和大气氮沉降量可以解释区域森林土壤N2O排放通量变化的55%。     

Linking Annual N2O Emission in Organic Soils to Mineral Nitrogen Input as Estimated by Heterotrophic Respiration and Soil C/N Ratio

Organic soils are an important source of N₂O, but global estimates of these fluxes remain uncertain because measurements are sparse. We tested the hypothesis that N₂O fluxes can be predicted from estimates of mineral nitrogen input, calculated from readily-available measurements of CO₂ flux and soil C/N ratio. From studies of organic soils throughout the world, we compiled a data set of annual CO₂ and N₂O fluxes which were measured concurrently. The input of soil mineral nitrogen in these studies was estimated from applied fertilizer nitrogen and organic nitrogen mineralization. The latter was calculated by dividing the rate of soil heterotrophic respiration by soil C/N ratio. This index of mineral nitrogen input explained up to 69% of the overall variability of N₂O fluxes, whereas CO₂ flux or soil C/N ratio alone explained only 49% and 36% of the variability, respectively. Including water table level in the model, along with mineral nitrogen input, further improved the model with the explanatory proportion of variability in N₂O flux increasing to 75%. Unlike grassland or cropland soils, forest soils were evidently nitrogen-limited, so water table level had no significant effect on N₂O flux. Our proposed approach, which uses the product of soil-derived CO₂ flux and the inverse of soil C/N ratio as a proxy for nitrogen mineralization, shows promise for estimating regional or global N₂O fluxes from organic soils, although some further enhancements may be warranted.     

Gaseous nitrogen emmissions from undisturbed terrestrial ecosystems: An assessment of their impacts on local and global nitrogen budgets

There is increasing interest in the importance of nitrogen gas emissions from natural (non-agricultural) ecosystems with respect to local as well as global nitrogen budgets and with respect to the effects of nitrogen oxides on atmospheric ozone levels and global warming. The volatile forms of nitrogen of common interest are ammonia (NH₃), nitrous oxide, (N₂O), dinitrogen (N₂), and NO_x (principally NO + NO₂). It is often difficult to attribute emissions of these compounds from soils to a single process because they are produced by a variety of common biogeochemical mechanisms. Although environmental conditions in the soil often appear to favor nitrogen gas emissions, the potential nitrogen gas emission rate from undisturbed ecosystems is rarely approached. The best estimates to date suggest that nitrogen gas emission rates from undisturbed ecosystems typically range from > 1 to perhaps 10 or 20 kg N ha^-1 yr^-1. Under certain conditions, however, emission rates may be much higher. For example, excreta from animals in grasslands may elevate ammonia volatilization up to 100 kg N ha^-1 yr^-1 depending on grazer density; tidal input of nutrients to coastal wetlands may support denitrification rates of several hundred kg N ha^-1 yr^-1 . Excepting such cases, gaseous nitrogen losses are probably a small component of the local nitrogen budget in most undisturbed ecosystems. However, emissions from undisturbed soils are an important component of the global source strengths for (N₂O + N₂), N₂O and NO_x (50%, 21%, and 10% respectively). Emission rates of N₂O from natural ecosystems are higher than assumed previously by perhaps 10 times. Large-scale disturbance may have a stimulatory effect on nitrogen emission rates which could have important effects on global nitrogen budgets. There is a need for more sophisticated methods to account for natural temporal and spatial variations of emissions rates, to more accurately and precisely assess their global source strengths.     

Elevated CO2 and nutrient addition after soil N cycling and N trace gas fluxes with early season wet-up in a California annual grassland

We examined the effects of growth carbon dioxide (CO₂)concentration and soil nutrient availability on nitrogen (N)transformations and N trace gas fluxes in California grasslandmicrocosms during early-season wet-up, a time when rates of Ntransformation and N trace gas flux are high. After plant senescenceand summer drought, we simulated the first fall rains and examined Ncycling. Growth at elevated CO₂ increased root productionand root carbon:nitrogen ratio. Under nutrient enrichment, elevatedCO₂ increased microbial N immobilization during wet-up,leading to a 43% reduction in gross nitrification anda 55% reduction in NO emission from soil. ElevatedCO₂ increased microbial N immobilization at ambientnutrients, but did not alter nitrification or NO emission. ElevatedCO₂ did not alter soil emission of N₂O ateither nutrient level. Addition of NPK fertilizer (1:1:1) stimulatedN mineralization and nitrification, leading to increased N₂Oand NO emission from soil. The results of our study support a mechanisticmodel in which elevated CO₂ alters soil N cycling and NOemission: increased root production and increased C:N ratio in elevatedCO₂ stimulate N immobilization, thereby decreasingnitrification and associated NO emission when nutrients are abundant.This model is consistent with our basic understanding of how C availabilityinfluences soil N cycling and thus may apply to many terrestrial ecosystems.     

Mineralization and gaseous losses of nitrogen from urea and ammonium sulphate in salt-affected soils

Summary An incubation study on mineralization and gaseous losses of nitrogen was conducted on three soils with increasing levels (1.1 to 50 mmhos/cm) of salinity and two levels of urea and ammonium sulphate upto 6 weeks. Mineralization of nitrogen increased with time and decreased with the increase of salinity. It was more from ammonium sulphate than urea, and relatively more from the lower dose. The gaseous losses of NH₄-N increased with salinity. About 35±5 per cent of added N was lost in the gaseous form at maximum (ECe=45 to 50 mmhos/cm) salinity and losses were more from light than heavier soils. Salinity and pH, both were correlated negatively with the N mineralisation and positively with the gaseous losses of ammonia in these salt-affected soils. re]19751105     

我国北方几种玉米和设施菜地土壤的N2O和N2排放特征

为了探究旱地土壤施入氮肥后的气态氮(N₂O和N₂)损失规律,本研究通过室内好氧培养试验(60 d,25 ℃,80%孔隙含水量),运用¹⁵N同位素示踪技术,研究了4个玉米地土壤(哈尔滨、沈阳、栾城、寿光)和2个设施菜地土壤(沈阳、寿光)在施入尿素后的氮转化、N₂O和N₂排放动态。试验中尿素添加量为167 mg N·kg^-1,以模拟田间氮肥施用量200 kg N·hm^-2。结果表明: 在4个玉米地土壤中,尿素施用60 d内N₂O累积排放量为寿光(20 mg N·kg^-1)>栾城(14 mg N·kg^-1)>沈阳(5 mg N·kg^-1)>哈尔滨(0.5 mg N·kg^-1),N₂累积排放量为栾城(176 mg N·kg^-1)>沈阳(106 mg N·kg^-1)>寿光(75 mg N·kg^-1)>哈尔滨(12 mg N·kg^-1);在2个设施菜地土壤中,寿光土壤N₂O累积排放量(21 mg N·kg^-1)是沈阳(2 mg N·kg^-1)的10倍,而两个站点N₂累积排放量分别为28和24 mg N·kg^-1。不同土壤N₂O排放占两种气体排放总量的5%～40%,其中寿光土壤(30%～40%)显著高于其他样地土壤(1%～10%)。在土壤排放的N₂O和N₂中,土壤氮库分别贡献了56%和61%,高于添加当季氮肥的贡献率。相关分析表明,N₂O累积排放量与本底土壤pH呈正相关,说明土壤本底pH可能是调控不同旱地土壤N₂O和N₂排放的重要环境因子。在华北碱性土壤区,采用能降低土壤pH值的措施可能具有较好的气态氮减排效果。     

Prevention and control of losses of gaseous nitrogen compounds in livestock operations: a review

Nitrogen (N) losses from livestock houses and manure storage facilities contribute greatly to the total loss of N from livestock farms. Volatilisation of ammonia (NH3) is the major process responsible for the loss of N in husbandry systems with slurry (where average dry matter content varies between 3 and 13%). Concerning this volatilisation of NH3, the process parameters of pH and air temperature are crucial. During a period of approximately 10 years, systematic measurements of NH3 losses originating from a large variety of different livestock houses were made. One of the problems with NH3 emissions is the large variation in the measured data due to the season, the production of the animals, the manure treatment, type of livestock house, and the manure storage. Generally speaking, prevention and control of NH3 emission can be done by control of N content in the manure, moisture content, pH, and temperature. In houses for growing pigs, a combination of simple housing measures can be taken to greatly reduce NH3 emissions. In houses for laying hens, the control of the manure drying process determines the emission of NH3. Monteny has built an NH3 production model with separate modules for the emission of the manure storage under the dairy house and the floor in the house. Manure spreading is also a major source of NH3 emission and is dependent on slurry composition, environmental conditions, and farm management. The effects of these factors have been employed in a model. Losses via NO, N2O, and N2 are important in husbandry systems with solid manure and straw. The number of experimental data is, however, very limited. As N2O is an intermediate product of complex biochemical processes of nitrification and denitrification, optimal conditions are the key issues in N2O reduction strategies. We may expect that in the near future the emission of greenhouse gases will get the same attention from policy makers as NH3. Sustainable livestock production has to combine low emissions of gaseous N compounds with acceptable odour emissions, low emissions of greenhouse gases, and acceptable standards of animal welfare. For the entrepreneur, the strategy must be built on the regulations, the special conditions of his farm, and what is reasonably achievable.