添加不同辅料对污泥堆肥腐熟度及气体排放的影响

选择玉米秸秆和木本泥炭两种辅料添加至脱水污泥中进行联合好氧堆肥,研究了秸秆和木本泥炭作为添加剂对污泥堆肥腐熟度和堆肥过程中气体排放(NH_3、CH_4和N_2O)的影响。两种辅料添加量均为初始物料的15%,堆肥在60 L的密闭反应器中共持续35 d。研究结果表明,秸秆作为添加剂与污泥联合堆肥,堆肥产品可以达到卫生标准和腐熟标准。添加秸秆处理整个堆肥过程中累积NH_3、CH_4和N_2O排放量分别为2.2、0.14和0.09 g/kg,NH_3和CH_4排放主要发生在堆肥的升温期和高温期,N_2O排放主要发生在堆肥的后腐熟阶段。添加木本泥炭作为添加剂不能成功启动堆肥,整个堆置过程中未检测到NH_3和CH_4排放,但是在堆肥前期有大量N_2O产生。对于添加秸秆的处理,CH_4、N_2O和NH_3对总温室气体排放的贡献率分别为45%,36%和19%,CH_4所占比重最高。     

Effects of activated charcoal and tannin added to compost and to soil on carbon dioxide,nitrous oxide and ammonia volatilization

Given high mineralization rates of soil organic matter addition of organic fertilizers such as compost and manure is a particularly important component of soil fertility management under irrigated subtropical conditions as in Oman. However, such applications are often accompanied by high leaching and volatilization losses of N. Two experiments were therefore conducted to quantify the effects of additions of activated charcoal and tannin either to compost in the field or directly to the soil. In the compost experiment, activated charcoal and tannins were added to compost made from goat manure and plant material at a rate of either 0.5 t activated charcoal ha^?1, 0.8 t tannin extract ha^?1, or 0.6 t activated charcoal and tannin ha^?1 in a mixed application. Subsequently, emissions of CO₂, N₂O, and NH₃ volatilization were determined for 69 d of composting. The results were verified in a 20‐d soil incubation experiment in which C and N emissions from a soil amended with goat manure (equivalent to 135 kg N ha^?1) and additional amendments of either 3 t activated charcoal ha^?1, or 2 t tannin extract ha^?1, or the sum of both additives were determined. While activated charcoal failed to affect the measured parameters, both experiments showed that peaks of gaseous CO₂ and N emission were reduced and/or occurred at different times when tannin was applied to compost and soil. Application of tannins to compost reduced cumulative gaseous C emissions by 40% and of N by 36% compared with the non‐amended compost. Tannins applied directly to the soil reduced emission of N₂O by 17% and volatilization of NH₃ by 51% compared to the control. However, emissions of all gases increased in compost amended with activated charcoal, and the organic C concentration of the activated charcoal amended soil increased significantly compared to the control. Based on these results, tannins appear to be a promising amendment to reduce gaseous emissions from composts, particularly under subtropical conditions.     

Effect of the long-term application of organic matter on soil carbon accumulation and GHG emissions from a rice paddy field in a cool-temperate region,Japan-II. Effect of different compost applications-

ABSTRACT

The influence of long-term application of different types of compost on rice grain yield, CH₄ and N₂O emissions, and soil carbon storage (0 ? 30 cm) in rice paddy fields was clarified. Two sets of paddy fields applied with rice straw compost or livestock manure compost mainly derived from cattle were used in this study. Each set comprised long-term application (LT) and corresponding control (CT) plots. The application rates for rice straw compost (42 years) and livestock manure compost (41 years in total with different application rates) were 20 Mg fresh weight ha^–1. Soil carbon storage increased by 33% and 37% with long-term application of rice straw compost and livestock manure compost, respectively. The soil carbon sequestration rate by the organic matter application was 23% higher with the livestock manure compost than with the rice straw compost. The rice grain yield in the LT plot was significantly higher than that in the corresponding CT plot with both types of compost. Although the difference was not significant in the rice straw compost, cumulative CH₄ emissions increased with long-term application of both composts. Increase rate of CH₄ emission with long-term application was higher in the livestock manure compost (99%) than that in the rice straw compost (26%). In both composts, the long-term application did not increase N₂O emission significantly. As with the rice straw compost, the increase in CH₄ emission with the long-term application of livestock manure compost exceeded the soil carbon sequestration rate, and the change in the net greenhouse gas (GHG) balance calculated by the difference between them was positive, indicating a net increase in the GHG emissions. The increase in CH₄ and net GHG emissions owing to the long-term application of the livestock manure compost could be higher than that of the rice straw compost owing to the amount of applied carbon, the quality of compost and the soil carbon accumulation. The possibility that carbon sequestration in the subsoil differs depending on the type of composts suggests the importance of including subsoil in the evaluation of soil carbon sequestration by long-term application of organic matter.     

Nitrous oxide, methane and ammonia emissions following slurry spreading on grassland

In Sweden, 90% of ammonia (NH₃) emissions to the atmosphere originate from agriculture, predominantly from animal manure handling. It is well known that incorporation of manure into soil can reduce NH₃ emissions after spreading. However, there is a risk of increased nitrous oxide (N₂O) and methane (CH₄) emissions caused by bacterial activity and limited oxygen availability under these conditions. A full‐scale injector was developed and evaluated in a field experiment on grassland. Cattle slurry was either injected in closed slots 5 cm below ground or band spread on the soil surface above the crop canopy at a rate of 25 t ha^?1. In a control treatment, no slurry was applied. During a 5‐day period after application, NH₃ emissions were measured using an equilibrium concentration method. Gas samples for estimating CH₄ and N₂O emissions were also collected during 7 weeks following slurry application. Injection in closed slots resulted in no detectable NH₃ emissions. After band spreading, however, NH₃ emissions corresponded to nearly 40% of the total ammoniacal nitrogen in the applied slurry. The injection of slurry gave rise to a broad peak of N₂O emissions during the first 3 weeks after application. In total, for the measuring period, N₂O emissions corresponded to 0.75 kg N ha^?1. Band spreading resulted in only a very small N₂O release of about 0.2 kg N ha^?1 during the same period. Except for the first sampling occasion, the soil was predominantly a sink for CH₄ in all the treatments. The use of the injector without slurry application reduced grass yield during unfavourable growing conditions. In conclusion, shallow injection in closed slots seems to be a promising technique to reduce negative environmental impacts from NH₃ emissions with a limited release of N₂O and CH₄.     

Temperature response of ammonia and greenhouse gas emission from manure amended silty clay soil

Soil temperature plays an important role in organic matter decomposition, thus likely to affect ammonia and gaseous emission from land application of manure. An incubation experiment was conducted to quantify ammonia and greenhouse gas (GHG) (N₂O, CO₂ and CH₄) emissions from manure and urea applied at 215?kg N ha^?1 to Fargo-Ryan silty clay soil. Soil (250?g) amended with solid beef manure (SM), straw-bedded solid beef manure (BM), urea only (UO), and control (CT) were incubated at 5, 10, 15, and 25 °C for 31 days at constant 60% water holding capacity (WHC). The cumulative GHGs and NH₃ emission generally increased with temperature and highest emission observed at 25 °C. Across temperature levels, 0.11–1.3% and 0.1–0.7% of the total N was lost as N₂O and NH₃, respectively. Cumulative CO₂ emission from manure was higher than UO and CT at all temperatures (P?<?0.05). Methane accounted for <0.1% of the total C (CO₂?+?CH₄) emission across temperatures. The Q₁₀ values (temperature sensitivity coefficient) derived from Arrhenius and exponential models ranged 1.5–3.7 for N₂O, 1.4–6.4 for CO₂, 1.6–5.8 for CH₄, and 1.4–5.0 for NH_3. Our results demonstrated that temperature significantly influences NH₃ and GHG emissions irrespective of soil amendment but the magnitude of emission varied with soil nutrient availability and substrate quality. Overall, the highest temperature resulted in the highest emission of NH₃ and GHGs.     

Effect of nitrite accumulation on nitrous oxide emission and total nitrogen loss during swine manure composting

Abstract

The present study investigated the nitrogen balance in swine manure composting to evaluate the effect of nitrite (NO^? ₂) accumulation, which induces nitrogenous emissions, such as N₂O, during compost maturation. During active composting, most N losses result from NH₃ emission, which was 9.5% of the initial total nitrogen (TN_initial), after which, NO^? ₂ began to accumulate as only ammonia-oxidizing bacteria proliferated. After active composting, the addition of mature swine compost (MSC), including nitrite-oxidizing bacteria (NOB), could prevent NO^? ₂ accumulation and reduce N₂O emission by 70% compared with the control in which NO^? ₂ accumulated as a result of delayed growth of indigenous NOB. Total N₂O emissions in the control and in the treatment of MSC addition (MA) were 9.3% and 3.0% of TN_initial, respectively, whereas N losses as the sum total of NH₃ and N₂O over the whole period were 19.0% (control) and 12.8% (MA) of TN_initial, respectively. However, the difference in total N losses was markedly greater than that measured as NH₃ and N₂O, which were 27.8% (control) and 13.3% (MA) of TN_initial, respectively. These results demonstrated that the magnitude of nitrogen losses induced by NO^? ₂ accumulation is too large to ignore in the composting of swine manure.     

The Maturity and CH4, N2O,NH3 Emissions from Vermicomposting with Agricultural Waste

This study investigated the maturity and gaseous emissions from vermicomposing with agricultural waste. A vermicomposting treatment (inoculated Eisenia fetida) was conducted over a 50-day period, taking tomato stems as the processing object and using cow dung as the nutrient substrate. A thermophilic composting treatment without earthworm inoculation was operated as a control treatment. During the experiment, maturity indexes such as temperature, pH, C/N ratio, and germination index (GI) were determined and continuous measurements of earthworm biomass and CH₄, N₂O, and NH₃ emissions were carried out. The results showed that the temperature during vermicomposting was suitable for earthworm survival, and the earthworm biomass increased from 10.0 to 63.1 kg m^?3. Vermicomposting took less time on average to reach the compost maturity standard (GI 80%), and reached a higher GI (132%) in the compost product compared with the thermophilic composting treatment. Moreover, the decrease of the C/N ratio in vermicompost indicated stabilization of the waste. The activities of earthworms played a positive role in reducing gaseous emissions in vermicompost, resulting in less emissions of NH₃ (12.3% NH₃-N of initial nitrogen) and total greenhouse gases (8.1 kg CO₂-eq/t DM) than those from thermophilic compost (24.9% NH₃-N of initial nitrogen, 22.8 kg CO₂-eq/t DM). Therefore, it can be concluded that vermicomposting can shorten the period required to reach compost maturity, can obtain better maturity compost, and at the same time reduce gaseous emissions. As an added advantage, the earthworms after processing could have commercial uses.     

Nitrous oxide and methane emissions from grassland treated with bark- or sawdust-containing manure at different rates

On the main Japanese island of Honshu, bark or sawdust is often added to cattle excreta as part of the composting process. Dairy farmers sometimes need to dispose of manure that is excess to their requirements by spreading it on their grasslands. We assessed the effect of application of bark- or sawdust-containing manure at different rates on annual nitrous oxide (N₂O) and methane (CH₄) emissions from a grassland soil. Nitrous oxide and CH₄ fluxes from an orchardgrass (Dactylis glomerata L.) grassland that received this manure at 0, 50, 100, 200, or 300?Mg?ha^?1?yr^?1 were measured over a two-year period by using closed chambers. Two-way analysis of variance (ANOVA) was employed to examine the effect of annual manure application rates and years on annual N₂O and CH₄ emissions. Annual N₂O emissions ranged from 0.47 to 3.03?kg?N?ha^?1?yr^?1 and increased with increasing manure application rate. Nitrous oxide emissions during the 140-day period following manure application increased with increasing manure application rate, with the total nitrogen concentration in the manure, and with cumulative precipitation during the 140-day period. However, manure application rate did not affect the N₂O emission factors of the manure. The overall average N₂O emission factor was 0.068%. Annual CH₄ emissions ranged from ?1.12 to 0.01?kg?C?ha^?1?yr^?1. The annual manure application rate did not affect annual CH₄ emissions.     

Influence of water depth and soil amelioration on greenhouse gas emissions from peat soil columns

Recently, large areas of tropical peatland have been converted into agricultural fields. To be used for agricultural activities, peat soils need to be drained, limed and fertilized due to excess water, low nutrient content and high acidity. Water depth and amelioration have significant effects on greenhouse gas (GHG) production. Twenty-seven soil samples were collected from Jabiren, Central Kalimantan, Indonesia, in 2014 to examine the effect of water depth and amelioration on GHG emissions. Soil columns were formed in the peatland using polyvinyl chloride (PVC) pipe with a diameter of 21 cm and a length of 100 cm. The PVC pipe was inserted vertically into the soil to a depth of 100 cm and carefully pulled up with the soil inside after sealing the bottom. The treatments consisting of three static water depths (15, 35 and 55 cm from the soil surface) and three ameliorants (without ameliorant/control, biochar+compost and steel slag+compost) were arranged using a randomized block design with two factors and three replications. Fluxes of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) from the soil columns were measured weekly. There was a linear relationship between water depth and CO₂ emissions. No significant difference was observed in the CH₄ emissions in response to water depth and amelioration. The ameliorations influenced the CO₂ and N₂O emissions from the peat soil. The application of biochar+compost enhanced the CO₂ and N₂O emissions but reduced the CH₄ emission. Moreover, the application of steel slag+compost increased the emissions of all three gases. The highest CO₂ and N₂O emissions occurred in response to the biochar+compost treatment followed by the steel slag-compost treatment and without ameliorant. Soil pH, redox potential (Eh) and temperature influenced the CO₂, CH₄ and N₂O fluxes. Experiments for monitoring water depth and amelioration should be developed using peat soil as well as peat soil–crop systems.     

How do greenhouse gas emissions vary with biofertilizer type and soil temperature and moisture in a tropical grassland?

Greenhouse gases are known to play an important role in global warming. In this study, we determined the effects of selected soil and climate variables on nitrous oxide (N₂O), methane (CH₄), and carbon dioxide (CO₂) emissions from a tropical grassland fertilized with chicken slurry, swine slurry, cattle slurry, and cattle compost. Cumulative N₂O emissions did not differ between treatments and varied from 29.26 to 32.85 mg N m^-2. Similarly, cumulative CH₄ emissions were not significantly different among the treatments and ranged from 6.34 to 57.73 mg CH₄ m^-2. Slurry and compost application induced CO₂ emissions that were significantly different from those in the control treatment. The CH₄ conversion factors measured were 0.21%, 1.39%, 4.39%, and 5.07% for cattle compost, chicken slurry, swine slurry, and cattle slurry, respectively, differing from the recommendations of the Intergovernmental Panel on Climate Change (IPCC). The fraction of added N emitted as N₂O was 0.39%, which was lower than the IPCC default value of 2%. Our findings suggest that N₂O emissions could be mitigated by replacing synthetic fertilizer sources with either biofertilizer or compost. Our results indicate the following:N₂O emission was mainly controlled by soil temperature, followed by soil moisture and then soil NH₄⁺ content; CH₄ fluxes were mainly controlled by soil moisture and chamber headspace temperature; and CO₂ fluxes were mainly controlled by chamber headspace temperature and soil moisture.     

二氧化锰对微好氧堆肥腐熟、温室气体及臭气排放的影响

为探究锰矿物添加对微好氧堆肥过程腐熟、温室气体和臭气排放的影响,以由厨余垃圾、水稻秸秆、羊粪和尾菜组成的多元混合物料堆肥为研究对象,共设3个处理,采用间歇通风方式,将通风速率为0.14 L/（kg·min）设置为好氧堆肥对照（CK）,速率为0.06 L/（kg·min）为微好氧处理（T1）,添加二氧化锰（MnO₂）的微好氧处理为T2。结果表明：多元废弃物好氧或微好氧堆肥在堆制70 d后均能腐熟,但T2处理腐熟度显著高于T1。微好氧处理T1、T2减少了26.47%～30.29%的NH₃和33.19%～38.60%的N₂O的排放,总温室效应减少了29.26%～31.38%。臭气的排放集中在前14 d,T1、T2处理的H₂S和VOCs的释放量显著增加了320.35%～501.04%和39.82%～53.63%。因此,微好氧堆肥可达到减排目的,但却加剧臭气的排放;MnO₂可提高促进堆肥腐熟,降低温室气体和臭气的排放。     

Composting and Value-Added Utilization of Manure From a Swine Finishing Facility

Swine manure and wood shavings used as a drying bed were removed from a High-Rise? hog facility following two production cycles. The manure was composted in aerated pilot-scale vessels for four weeks or a mechanically turned windrow for ten weeks. Total dry matter losses during the pilot-scale studies were 30 and 32.5 % for continuously and intermittently aerated systems, respectively. Compost from both systems was stable with emission rates of 0.07-0.11 mgCO₂ h^?1 g_vs^?1. Moisture, O₂, CO₂ and NH₃ use/losses during the process as well as chemical properties of the initial and composted manure are presented. Incorporation of the compost at a 5% amendment rate (v/v) into a standard pine bark container medium significantly (P = 0.05) increased growth of two woody plant species. Higher amendment rates were toxic to some plants due to high initial NH₄⁺ concentrations in the medium. The compost significantly (P=0.05) increased growth and suppressed Pythium root rot of poinsettia when incorporated at 10% (v/v) into a standard sphagnum peat mix. The compost can be utilized as a value-added disease-suppressive product in the ornamentals industry.     

木本泥炭添加比例对猪粪堆肥腐熟度和污染及温室气体排放的影响

针对当前猪粪好氧堆肥过程中存在的腐熟度低、氮素损失严重、污染气体排放量大等问题,该研究以木本泥炭作为添加剂与猪粪进行联合堆肥,研究了不同木本泥炭添加量(添加比例依次为占物料湿基质量的5%、10%、15%和20%的4个处理)对猪粪好氧堆肥产品腐熟度和堆肥过程中CH4、NH3和H2S等污染气体排放变化的影响。结果表明:在猪粪堆肥中添加木本泥炭作为调理材料,堆体可成功启动升温,在第2~4天堆体可进入高温期,并持续7 d以上,达到无害化卫生标准;经28 d好氧堆肥以后,堆肥产品p H值为8.0左右,电导率值为1.47~1.82 m S/cm,发芽指数均大于80%,达到腐熟标准;木本泥炭添加量增加至15%以上时,有机质分解程度高,物料干质量降解率达22%左右,28 d堆体含水率下降35%左右,CH4、NH3和H2S排放量分别减少82.12%~89.48%、53.47%~63.31%、50.98%~62.76%,总温室气体排放当量减少70.34%~83.26%,堆体总氮损失减少率达44%~63%,保氮效果显著。因此,建议木本泥炭用作猪粪堆肥添加剂的最优添加量为15%~20%(以物料总湿重计)。     

NH3 Volatilization,N2O Emission and Microbial Biomass Turnover from 15N-Labeled Manure Under Laboratory Conditions

On irrigated agricultural soils from semi-arid and arid regions, ammonia (NH₃) volatilization and nitrous oxide (N₂O) emission can be a considerable source of N losses. This study was designed to test the capture of ¹⁵N loss as NH₃ and N₂O from previous and recent manure application using a sandy, calcareous soil from Oman amended one or two times with ¹⁵N labeled manure to elucidate microbial turnover processes under laboratory conditions. The system allowed to detect ¹⁵N enrichments in evolved N₂O-N and NH₃-N of up to 17% and 9%, respectively, and total N, K₂SO₄ extractable N and microbial N pools from previous and recent ¹⁵N labeled manure applications of up to 7%, 8%, and 15%. One time manured soil had higher cumulative N₂O-N emissions (141 µg kg^?1) than repeatedly manured soil with 43 µg kg^?1 of which only 22% derived from recent manure application indicating a priming effect.     

Impacts of pellet pH on nitrous oxide emission rates from cattle manure compost pellets

Previous reports indicated that the emission of nitrous oxide (N₂O) when manure compost pellets (MCP) were applied to soil was greater than when ordinary manure compost or inorganic fertilizer was applied, but that applying pellets of nitrogen-enriched manure compost, a by-product of deodorizing manure during composting, resulted in N₂O emission rates less than those from MCPs. To investigate the mechanism by which N₂O emission rates and cumulative emissions were reduced in nitrogen-enriched manure composts pellets (N+MCP), we studied the impact of pellet pH on N₂O emission, because pH is different between MCP (pH 8.6) and N+MCP (pH 5.3). In an incubation experiment, the pH of pellets was adjusted to five levels (5.3, 6.0, 7.0, 8.0 and 8.6) with acid or alkaline solutions, and the pellets were incubated without soil in a beaker at 30°C for 90 d (MCP) or 42 d (N+MCP). A large peak in N₂O emission rate was observed soon after beginning the incubation (within 1–3 d) in the neutral and alkaline treatments for both MCP and N+MCP, and these peaks corresponded to a rise in the pellet nitrite contents. Thus, this N₂O emission peak might have been generated by the denitrification of nitrite in the pellets. In the acid treatments of MCP, the N₂O emission was distributed more in the later incubation period (14–90 d), when the reduction of nitrate in MCP occurred. This led to a significant increase in cumulative N₂O emission as compared with the alkaline treatments for MCP. Regarding the mechanism by which N₂O emission was reduced in N+MCP, although larger cumulative N₂O emission rates in the earlier stage (0–14 d for MCP and 0–7 d for N+MCP) were observed when the pellet pH was adjusted close to 7.0, lowering the pH of MCP to 5.3 (the pH of N+MCP) did not demonstrate a significant decrease in cumulative N₂O emission as compared with the original pH treatment (pH 8.6). These results indicate that pellet pH might not relate directly to the mechanism by which N₂O emission was reduced in N+MCP.     

Use of nitrogen process inhibitors for reducing gaseous nitrogen losses from land-applied farm effluents

Applications of dairy farm effluents to land may lead to ammonia (NH₃) volatilization and nitrous oxide (N₂O) emissions. Nitrogen (N) transformation process inhibitors, such as urease inhibitors (UIs) and nitrification inhibitors (NIs), have been used to reduce NH₃ and N₂O losses derived from agricultural N sources. The objective of this study was to examine the effects of amending dairy effluents with UI (N-(n-butyl) thiophosphoric triamide (NBTPT)) and NI (dicyandiamide (DCD)) on NH₃ and N₂O emissions. Treatments included either fresh or stored manure and either fresh or stored farm dairy effluent (FDE), with and without NBTPT (0.25 g kg^?1 N) or DCD (10 kg ha^?1), applied to a pasture on a free-draining volcanic parent material soil. The nutrient loading rate of FDE and manure, which had different dry matter contents (about 2 and 11 %, respectively) was 100 kg N ha^?1. Application of manure and FDE led to NH₃ volatilization (15, 1, 17 and 0.4 % of applied N in fresh manure, fresh FDE, stored manure and stored FDE, respectively). With UI (NBTPT), NH₃ volatilization from fresh manure was significantly (P?<?0.05) decreased to 8 % from 15 % of applied N, but the UI did not significantly reduce NH₃ volatilization from fresh FDE. The N₂O emission factors (amount of N₂O–N emitted as a percentage of applied N) for fresh manure, fresh FDE and stored FDE were 0.13?±?0.02, 0.14?±?0.03 and 0.03?±?0.01 %, respectively. The NI (DCD) was effective in decreasing N₂O emissions from stored FDE, fresh FDE and fresh manure by 90, 51 and 46 % (P?<?0.05), respectively. All types of effluent increased pasture production over the first 21 days after application (P?<?0.05). The addition of DCD resulted in an increase in pasture production at first harvest on day 21 (P?<?0.05). This study illustrates that UIs and NIs can be effective in mitigating NH₃ and N₂O emissions from land-applied dairy effluents.     

Effects of green manure storage and incorporation methods on nitrogen release and N2O emissions after soil application

More efficient use of green manure-derived nitrogen (N) may improve crop yields and reduce environmental impacts in stockless organic arable farming. In this 3-month incubation study, we tested a new strategy where green manure leys are harvested and preserved until the following spring either as compost mixed with straw or as silage of harvested ley biomass. Grass-clover compost or silage was soil-incorporated by either simulated ploughing (green manure placed at 15 cm depth) or harrowing (green manure mixed into the upper 5-cm soil horizon) in order to assess treatment effects on net release of plant-available N, nitrous oxide (N₂O) fluxes and soil respiration. Grass-clover silage provided the highest net N release with similar results for the two incorporation methods. Up to one third of the total N content in silage became plant-available during the 3 months. In contrast, no net N release was observed for the composted grass-clover and straw mixture. In fact, soil incorporation of compost by harrowing caused temporal immobilization of soil mineral N. Silage incorporated by ploughing gave rise to the largest N₂O effluxes with silage-induced emissions corresponding to 0.3 % of applied total N. Possibly N₂O production via denitrification was stimulated by oxygen-limited conditions near the decomposing silage. In contrast, compost incorporated by harrowing caused net N₂O uptake, presumably an effect of reduced mineral N availability in this treatment. Overall, our study revealed that ensiled grass-clover was the best fertilizer product and that the method chosen for incorporation of green manure is likely to influence N₂O emissions.     

Ammonia and Nitrous Oxide Emissions after Landspreading of Slurry as Influenced by Application Technique and Dry Matter-Reduction. II. Short Term Nitrous Oxide Emissions

Strategies reducing NH₃ volatilisation from slurry include separation of slurry, special application techniques and additives. We studied the impact of manure separation and application technique on N₂O release after manure application. Untreated and separated cattle slurry (dry matter content of 7.1% and 4.4%, respectively) was applied to winter wheat using broadcast and banded application and injection. The N₂O emissions were measured at high frequency for 14 to 20 days after slurry treatment by the closed chamber method. Manured plots showed significantly higher N₂O emissions than the control plots but neither dry matter reduction of slurry nor application technique significantly influenced the N₂O emissions. The variability of N₂O emission was influenced by the application technique and increased in the order: banded application – injection – broadcast application. There was no correlation between NH₃ losses from applied slurry and N₂O emissions. Thus reducing ammonia volatilisation will not necessarily increase N₂O emissions.     

碳氮比对鸡粪堆肥腐熟度和臭气排放的影响

为确定鸡粪堆肥最优碳氮比（C/N比）,该研究以新鲜鸡粪为堆肥原料,添加玉米秸秆调节初始C/N比为14、18和22进行好氧堆肥,研究不同C/N比对鸡粪堆肥腐熟度和臭气排放（NH3和H2S）的影响。结果表明：C/N比为14的处理堆肥产品未腐熟,C/N比为18和22的处理均达到腐熟。C/N比为18的处理NH3累积排放量和总氮（TN）损失率最高;C/N比为18～22时,C/N比越高,NH3累积排放量和TN损失率越低。C/N比为14的处理H2S累积排放量和总硫（TS）损失率最高;C/N比为18和22的两个处理,H2S累积排放量显著降低,且无显著差异。此外,C/N比为18处理的微生物群落多样性在整个堆肥过程中显著高于C/N比为14和22处理。堆肥的理化指标、臭气排放与微生物群落之间的相关性分析表明,高温、高pH和缺氧环境会增加Firmicutes丰度,进而促进NH3和H2S的排放,相反地,低温、低pH和氧气充足的环境更有利于Actinobacteria增殖,有利于减少NH3和H2S的排放。综合考虑堆肥产品腐熟度和臭气减排效果,建议低C/N比鸡粪堆肥的初始C/N比为18～22。当秸秆资源不足时,建议初始C/N比为18;秸秆资源充足时,建议初始C/N比为22。     

Carbon dioxide, nitrous oxide and methane dynamics in boreal organic agricultural soils with different soil characteristics

The annual carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄) dynamics were measured with static chambers on two organic agricultural soils with different soil characteristics. Site 1 had a peat layer of 30 cm, with an organic matter (OM) content of 74% in the top 20 cm. Site 2 had a peat layer of 70 cm but an OM content of only 40% in the top 20 cm. On both sites there were plots under barley and grass and also plots where the vegetation was removed. All soils were net sources of CO₂ and N₂O, but they consumed atmospheric CH₄. Soils under barley had higher net CO₂ emissions (830 g CO₂-C m⁻² yr⁻¹) and N₂O emissions (848 mg N₂O-N m⁻² yr⁻¹) than those under grass (395 g CO₂-C m⁻³ yr⁻¹ and 275 mg N₂O-N m⁻² yr⁻¹). Bare soils had the highest N₂O emissions, mean 2350 mg N₂O-N m⁻² yr⁻¹. The mean CH₄ uptake rate from vegetated soils was 100 mg CH₄-C m⁻³ yr⁻¹ and from bare soils 55 mg CH₄-C m⁻² yr⁻¹. The net CO₂ emissions were higher from Site 2, which had a high peat bulk density and a low OM content derived from the addition of mineral soil to the peat during the cultivation history of that site. Despite the differences in soil characteristics, the mean N₂O emissions were similar from vegetated peat soils from both sites. However, bare soils from Site 2 with mineral soil addition had N₂O emissions of 2-9 times greater than those from Site 1. Site 1 consumed atmospheric CH₄ at a higher rate than Site 2 with additional mineral soil. N₂O emissions during winter were an important component of the N₂O budget even though they varied greatly, ranging from 2 to 99% (mean 26%) of the annual emission.