Effects of straw returning and feeding on greenhouse gas emissions from integrated rice-crayfish farming in Jianghan Plain,China

Great efforts have been devoted to assessing the effects of straw managements on greenhouse gas (GHG) emissions, global warming potential (GWP), and net economic budget in rice monoculture (RM). However, few studies have evaluated the effects of straw managements on GHG emissions and net ecosystem economic budget (NEEB) in integrated rice-crayfish farming (RC). Here, a randomized block field experiment was performed to comprehensively evaluate the effects of aquatic breeding practices (feeding or no feeding of forage) and straw managements (rice straw returning or removal) on soil NH₄⁺–N and NO^?₃–N contents, redox potential (Eh), CH₄ and N₂O emissions, GWP, and NEEB of fluvo-aquic paddy soil in a rice-crayfish co-culture system in Jianghan Plain of China. We also compared the differences in CH₄ and N₂O emissions, GWP, and NEEB between RM and RC. Straw returning significantly increased CH₄ and N₂O emissions by 34.9–46.1% and 6.2–23.1% respectively compared with straw removal. Feeding of forage decreased CH₄ emissions by 13.9–18.7% but enhanced N₂O emissions by 24.4–33.2% relative to no feeding. Compared with RM treatment, RC treatment decreased CH₄ emissions by 18.1–19.6% but increased N₂O emissions by 16.8–21.0%. Moreover, RC treatment decreased GWP by 16.8–22.0% while increased NEEB by 26.9–75.6% relative to RM treatment, suggesting that the RC model may be a promising option for mitigating GWP and increasing economic benefits of paddy fields. However, the RC model resulted in a lower grain yield compared with the RM model, indicating that more efforts are needed to simultaneously increase grain yield and NEEB and decrease GWP under RC model.

     

Temporal variability of soil-atmospheric CO2 and CH4 fluxes from different land uses in mid-subtropical China

Different land uses in subtropics play an important role in regulating the global environmental changes. To reduce uncertainties of greenhouse gas (GHG) emissions of agricultural soils in subtropical ecosystem, a four years campaign was started to determine the temporal GHG (CO₂ and CH₄) fluxes from seven sites of four land use types (1 vegetable field, 3 uplands, 2 orchards, 1 pine forest). The mean annual budgets of CO₂, and CH₄ were 6.5～10.5 Mg CO₂ ha^?1 yr^?1, and +0.47 ～ ?2.37 kg CH₄ ha^?1 yr^?1, respectively. Pine forest had significantly lower CO₂ emission and higher CH₄ uptake than agriculture land uses. Tilled orchard emitted more CO₂ and oxidized less CH₄ than non-tilled orchard. Upland crops had higher CO₂ emissions than orchards, while abrupt differences of CH₄ uptake were observed between upland crops and orchards. Every year, the climate was warm and wet from April to September (the hot–humid season) and became cool and dry from October to March (the cool–dry season). Driven by seasonality of temperature and WFPS, CO₂ fluxes were significantly higher in the hot–humid season than in cool–dry season. Soil temperature, WFPS, NO₃^?–N and NH₄⁺–N contents interactively explained CH₄ uptake which was significantly higher in cool–dry season than in hot–humid season. We conclude that soil C fluxes from different land uses are strongly under control of different climatic predictors along with soil nutrient status, which interact in conjunction with each other to supply the readily available substrates.     

Estimating and comparing greenhouse gas emissions with their uncertainties using different methods: A case study for an energy supply utility

Energy supply utilities release significant amounts of greenhouse gases (GHGs) into the atmosphere. It is essential to accurately estimate GHG emissions with their uncertainties, for reducing GHG emissions and mitigating climate change. GHG emissions can be calculated by an activity-based method (i.e., fuel consumption) and continuous emission measurement (CEM). In this study, GHG emissions such as CO₂, CH₄, and N₂O are estimated for a heat generation utility, which uses bituminous coal as fuel, by applying both the activity-based method and CEM. CO₂ emissions by the activity-based method are 12–19% less than that by the CEM, while N₂O and CH₄ emissions by the activity-based method are two orders of magnitude and 60% less than those by the CEM, respectively. Comparing GHG emissions (as CO₂ equivalent) from both methods, total GHG emissions by the activity-based methods are 12–27% lower than that by the CEM, as CO₂ and N₂O emissions are lower than those by the CEM. Results from uncertainty estimation show that uncertainties in the GHG emissions by the activity-based methods range from 3.4% to about 20%, from 67% to 900%, and from about 70% to about 200% for CO₂, N₂O, and CH₄, respectively, while uncertainties in the GHG emissions by the CEM range from 4% to 4.5%. For the activity-based methods, an uncertainty in the Intergovernmental Panel on Climate Change (IPCC) default net calorific value (NCV) is the major uncertainty contributor to CO₂ emissions, while an uncertainty in the IPCC default emission factor is the major uncertainty contributor to CH₄ and N₂O emissions. For the CEM, an uncertainty in volumetric flow measurement, especially for the distribution of the volumetric flow rate in a stack, is the major uncertainty contributor to all GHG emissions, while uncertainties in concentration measurements contribute a little to uncertainties in the GHG emissions.

Implications:Energy supply utilities contribute a significant portion of the global greenhouse gas (GHG) emissions. It is important to accurately estimate GHG emissions with their uncertainties for reducing GHG emissions and mitigating climate change. GHG emissions can be estimated by an activity-based method and by continuous emission measurement (CEM), yet little study has been done to calculate GHG emissions with uncertainty analysis. This study estimates GHG emissions and their uncertainties, and also identifies major uncertainty contributors for each method.     

Evaluating recycling fertilizers for tomato cultivation in hydroponics,and their impact on greenhouse gas emissions

Soilless culture systems offer an environmentally friendly and resource-efficient alternative to traditional cultivation systems fitting within the scheme of a circular economy. The objective of this research was to examine the sustainable integration of recycling fertilizers in hydroponic cultivation—creating a nutrient cycling concept for horticultural cultivation. Using the nutrient film technique (NFT), three recycling-based fertilizer variants were tested against standard synthetic mineral fertilization as the control, with 11 tomato plants (Solanum lycopersicum L. cv. Pannovy) per replicate (n = 4) and treatment: two nitrified urine-based fertilizers differing in ammonium/nitrate ratio (NH₄⁺:NO₃^?), namely (1) “Aurin” (AUR) and (2) “Crop” (CRO); as well as (3) an organo-mineral mixture of struvite and vinasse (S+V); and (4) a control (NPK). The closed chamber method was adapted for gas fluxes (N₂O, CH₄, and CO₂) from the root zone. There was no indication in differences of the total shoot biomass fresh matter and uptake of N, P and K between recycling fertilizers and the control. Marketable fruit yield was comparable between NPK, CRO and S+V, whereas lower yields occurred in AUR. The higher NH₄⁺:NO₃^? of AUR was associated with an increased susceptibility of blossom-end-rot, likely due to reduced uptake and translocation of Ca. Highest sugar concentration was found in S+V, which may have been influenced by the presence of organic acids in vinasse. N₂O emissions were highest in S+V, which corresponded to our hypothesis that N₂O emissions positively correlate with organic-C input by the fertilizer amendments. Remaining treatments showed barely detectable GHG emissions. A nitrified urine with a low NH₄⁺:NO₃^– (e.g., CRO) has a high potential as recycling fertilizer in NFT systems for tomato cultivation, and S+V proved to supply sufficient P and K for adequate growth and yield. Alternative cultivation strategies may complement the composition of AUR.

     

Greenhouse gas production and efficiency of planted and artificially aerated constructed wetlands

Greenhouse gas (GHG) emissions by constructed wetlands (CWs) could mitigate the environmental benefits of nutrient removal in these man-made ecosystems. We studied the effect of 3 different macrophyte species and artificial aeration on the rates of nitrous oxide (N₂O), carbon dioxide (CO₂) and methane (CH₄) production in CW mesocosms over three seasons. CW emitted 2-10 times more GHG than natural wetlands. Overall, CH₄ was the most important GHG emitted in unplanted treatments. Oxygen availability through artificial aeration reduced CH₄ fluxes. Plant presence also decreased CH₄ fluxes but favoured CO₂ production. Nitrous oxide had a minor contribution to global warming potential (GWP < 15%). The introduction of oxygen through artificial aeration combined with plant presence, particularly Typha angustifolia, had the overall best performance among the treatments tested in this study, including lowest GWP, greatest nutrient removal, and best hydraulic properties.     

A comparison of CH4, N2O and CO2 emissions from three different cover types in a municipal solid waste landfill

High-density polyethylene (HDPE) membranes are commonly used as a cover component in sanitary landfills, although only limited evaluations of its effect on greenhouse gas (GHG) emissions have been completed. In this study, field GHG emission were investigated at the Dongbu landfill, using three different cover systems: HDPE covering; no covering, on the working face; and a novel material-Oreezyme Waste Cover (OWC) material as a trial material. Results showed that the HDPE membrane achieved a high CH₄ retention, 99.8% (CH₄ mean flux of 12 mg C m^-2 h^-1) compared with the air-permeable OWC surface (CH4 mean flux of 5933 mg C m^-2 h^-1) of the same landfill age. Fresh waste at the working face emitted a large fraction of N₂O, with average fluxes of 10 mg N m^-2 h^-2, while N₂O emissions were small at both the HDPE and the OWC sections. At the OWC section, CH₄ emissions were elevated under high air temperatures but decreased as landfill age increased. N₂O emissions from the working face had a significant negative correlation with air temperature, with peak values in winter. A massive presence of CO₂ was observed at both the working face and the OWC sections. Most importantly, the annual GHG emissions were 4.9 Gg yr^-1 in CO₂ equivalents for the landfill site, of which the OWC-covered section contributed the most CH₄ (41.9%), while the working face contributed the most N₂O (97.2%). HDPE membrane is therefore, a recommended cover material for GHG control.

Implications: Monitoring of GHG emissions at three different cover types in a municipal solid waste landfill during a 1-year period showed that the working face was a hotspot of N₂O, which should draw attention. High CH₄ fluxes occurred on the permeable surface covering a 1- to 2-year-old landfill. In contrast, the high-density polyethylene (HDPE) membrane achieved high CH₄ retention, and therefore is a recommended cover material for GHG control.     

Mitigating Global Warming Potentials of Methane and Nitrous Oxide Gases from Rice Paddies under different irrigation regimes

A field experiment was conducted in Bangladesh Agricultural University Farm to investigate the mitigating effects of soil amendments such as calcium carbide, calcium silicate, phosphogypsum, and biochar with urea fertilizer on global warming potentials (GWPs) of methane (CH₄) and nitrous oxide (N₂O) gases during rice cultivation under continuous and intermittent irrigations. Among the amendments phosphogypsum and silicate fertilizer, being potential source of electron acceptors, decreased maximum level of seasonal CH₄ flux by 25–27 % and 32–38 % in continuous and intermittent irrigations, respectively. Biochar and calcium carbide amendments, acting as nitrification inhibitors, decreased N₂O emissions by 36–40 % and 26–30 % under continuous and intermittent irrigations, respectively. The total GWP of CH₄ and N₂O gases were decreased by 7–27 % and 6–34 % with calcium carbide, phosphogypsum, and silicate fertilizer amendments under continuous and intermittent irrigations, respectively. However, biochar amendments increased overall GWP of CH₄ and N₂O gases.     

Greenhouse gas emissions from dairy open lot and manure stockpile in northern China: A case study

The open lots and manure stockpiles of dairy farm are major sources of greenhouse gas (GHG) emissions in typical dairy cow housing and manure management system in China. GHG (CO₂, CH₄ and N₂O) emissions from the ground level of brick-paved open lots and uncovered manure stockpiles were estimated according to the field measurements of a typical dairy farm in Beijing by closed chambers in four consecutive seasons. Location variation and manure removal strategy impacts were assessed on GHG emissions from the open lots. Estimated CO₂, CH₄ and N₂O emissions from the ground level of the open lots were 137.5±64.7 kg hd^-1 yr^-1, 0.45±0.21 kg hd^-1 yr^-1 and 0.13±0.08 kg hd^-1 yr^-1, respectively. There were remarkable location variations of GHG emissions from different zones (cubicle zone vs. aisle zone) of the open lot. However, the emissions from the whole open lot were less affected by the locations. After manure removal, lower CH₄ but higher N₂O emitted from the open lot. Estimated CO₂, CH₄ and N₂O emissions from stockpile with a stacking height of 55±12 cm were 858.9±375.8 kg hd^-1 yr^-1, 8.5±5.4 kg hd^-1 yr^-1 and 2.3±1.1 kg hd^-1 yr^-1, respectively. In situ storage duration, which estimated by manure volatile solid contents (VS), would affect GHG emissions from stockpiles. Much higher N₂O was emitted from stockpiles in summer due to longer manure storage.

Implications: This study deals with greenhouse gas (GHG) emissions from open lots and stockpiles. It’s an increasing area of concern in some livestock producing countries. The Intergovernmental Panel on Climate Change (IPCC) methodology is commonly used for estimation of national GHG emission inventories. There is a shortage of on-farm information to evaluate the accuracy of these equations and default emission factors. This work provides valuable information for improving accounting practices within China or for similar manure management practice in other countries.     

Life cycle energy use,costs, and greenhouse gas emission of broiler farms in different production systems in Iran—a case study of Alborz province

In order to achieve sustainable development in agriculture, it is necessary to quantify and compare the energy, economic, and environmental aspects of products. This paper studied the energy, economic, and greenhouse gas (GHG) emission patterns in broiler chicken farms in the Alborz province of Iran. We studied the effect of the broiler farm size as different production systems on the energy, economic, and environmental indices. Energy use efficiency (EUE) and benefit-cost ratio (BCR) were 0.16 and 1.11, respectively. Diesel fuel and feed contributed the most in total energy inputs, while feed and chicks were the most important inputs in economic analysis. GHG emission calculations showed that production of 1000 birds produces 19.13 t CO_2-eq and feed had the highest share in total GHG emission. Total GHG emissions based on different functional units were 8.5 t CO_2-eq per t of carcass and 6.83 kg CO_2-eq per kg live weight. Results of farm size effect on EUE revealed that large farms had better energy management. For BCR, there was no significant difference between farms. Lower total GHG emissions were reported for large farms, caused by better management of inputs and fewer bird losses. Large farms with more investment had more efficient equipment, resulting in a decrease of the input consumption. In view of our study, it is recommended to support the small-scale broiler industry by providing subsidies to promote the use of high-efficiency equipment. To decrease the amount of energy usage and GHG emissions, replacing heaters (which use diesel fuel) with natural gas heaters can be considered. In addition to the above recommendations, the use of energy saving light bulbs may reduce broiler farm electricity consumption.     

Note on In-Traffic Measurement of Airborne Tire-Wear Participate Debris

Measuring greenhouse gas (GHG) source emissions provides data for validation of GHG inventories, which provide the foundation for climate change mitigation. Two Toyota RAV4 electric vehicles were outfitted with high-precision instrumentation to determine spatial and temporal resolution of GHGs (e.g., nitrous oxide, methane [CH₄], and carbon dioxide [CO₂]), and other gaseous species and particulate metrics found near emission sources. Mobile measurement platform (MMP) analytical performance was determined over relevant measurement time scales. Pollutant residence times through the sampling configuration were measured, ranging from 3 to 11 sec, enabling proper time alignment for spatial measurement of each respective analyte. Linear response range for GHG analytes was assessed across expected mixing ratio ranges, showing minimal regression and standard error differences between 5, 10, 30, and 60 sec sampling intervals and negligible differences between the two MMPs. GHG instrument drift shows deviation of less than 0.8% over a 24-hr measurement period. These MMPs were utilized in tracer-dilution experiments at a California landfill and natural gas compressor station (NGCS) to quantify CH₄ emissions. Replicate landfill measurements during October 2009 yielded annual CH₄ emissions estimates of 0.10 ± 0.01, 0.11 ± 0.01, and 0.12 ± 0.02 million tonnes of CO₂ equivalent (MTCO₂E). These values compare favorably to California GHG Emissions Inventory figures for 2007, 2008, and 2009 of 0.123, 0.125, and 0.126 MTCO₂E/yr, respectively, for this facility. Measurements to quantify NGCS boosting facility-wide emissions, during June 2010 yielded an equivalent of 5400 ± 100 TCO₂E/yr under steady-state operation. However, measurements during condensate transfer without operational vapor recovery yield an instantaneous emission rate of 2–4 times greater, but was estimated to only add 12 TCO₂E/yr overall. This work displays the utility for mobile GHG measurements to validate existing measurement and modeling approaches, so emission inventory values can be confirmed and associated uncertainties reduced.

Implications:?Measuring greenhouse gas (GHG) source emissions provides data and validation for GHG inventories, the foundation for climate change mitigation. Mobile measurement platforms with robust analytical instrumentation completed tracer-dilution experiments in California at a landfill and natural gas compressor station (NGCS) to quantify CH₄ emissions. Data collected for landfill CH₄ agree with the current California emissions inventory, while NGCS data show the possible variability from this type of facility. This work displays the utility of mobile GHG measurements to validate existing measurement and modeling approaches, such that emission inventory values can be confirmed, associated uncertainties reduced, and mitigation efforts quantified.     

An estimate of the contribution of outdoor concrete yards used by livestock to the UK inventories of ammonia, nitrous oxide and methane

Many farms have unroofed concrete yards used by livestock. These concrete yards have received little attention as sources of gaseous emissions. From 1997 to 1999 measurements were made of emissions of ammonia (NH₃), nitrous oxide (N₂O) and methane (CH₄) from 11 concrete yards used by livestock. A postal survey was carried out to assess the areas of yards on farms in England and Wales to enable the measurements to be scaled up to estimate national emissions. Using the results of this study NH₃-N emissions from farm concrete yards were calculated to be ca. 35×10³ t annually. This is 13% of the current estimated total NH₃-N emission from UK livestock. Concrete yards were an insignificant source of N₂O and CH₄ which were both <0.01% of current estimates of agricultural emissions.     

Greenhouse gas emissions from penguin guanos and ornithogenic soils in coastal Antarctica: Effects of freezing–thawing cycles

In coastal Antarctica, freezing and thawing influence many physical, chemical and biological processes for ice-free tundra ecosystems, including the production of greenhouse gases (GHGs). In this study, penguin guanos and ornithogenic soil cores were collected from four penguin colonies and one seal colony in coastal Antarctica, and experimentally subjected to three freezing–thawing cycles (FTCs) under ambient air and under N₂. We investigated the effects of FTCs on the emissions of three GHGs including nitrous oxide (N₂O), carbon dioxide (CO₂) and methane (CH₄). The GHG emission rates were extremely low in frozen penguin guanos or ornithogenic soils. However, there was a fast increase in the emission rates of three GHGs following thawing. During FTCs, cumulative N₂O emissions from ornithogenic soils were greatly higher than those from penguin guanos under ambient air or under N₂. The highest N₂O cumulative emission of 138.24 μg N₂O–N kg^?1 was observed from seal colony soils. Cumulative CO₂ and CH₄ emissions from penguin guanos were one to three orders of magnitude higher than those from ornithogenic soils. The highest cumulative CO₂ (433.0 mgCO₂–C kg^?1) and CH₄ (2.9 mgCH₄–C kg^?1) emissions occurred in emperor penguin guanos. Penguin guano was a stronger emitter for CH₄ and CO₂ while ornithogenic soil was a stronger emitter for N₂O during FTCs. CO₂ and CH₄ fluxes had a correlation with total organic carbon (TOC) and soil/guano moisture (M_c) in penguin guanos and ornithogenic soils. The specific CO₂–C production rate (CO₂–C/TOC) indicated that the bioavailability of TOC was markedly larger in penguin guanos than in ornithogenic soils during FTCs. This study showed that FTC-released organic C and N from sea animal excreta may play a significant role in FTC-related GHG emissions, which may account for a large proportion of annual fluxes from tundra ecosystems in coastal Antarctica.     

Chemical amendment of pig slurry: control of runoff related risks due to episodic rainfall events up to 48 h after application

Losses of phosphorus (P) from soil and slurry during episodic rainfall events can contribute to eutrophication of surface water. However, chemical amendments have the potential to decrease P and suspended solids (SS) losses from land application of slurry. Current legislation attempts to avoid losses to a water body by prohibiting slurry spreading when heavy rainfall is forecast within 48 h. Therefore, in some climatic regions, slurry spreading opportunities may be limited. The current study examined the impact of three time intervals (TIs; 12, 24 and 48 h) between pig slurry application and simulated rainfall with an intensity of 11.0?±?0.59 mm h^?1. Intact grassed soil samples, 1 m long, 0.225 m wide and 0.05 m deep, were placed in runoff boxes and pig slurry or amended pig slurry was applied to the soil surface. The amendments examined were: (1) commercial-grade liquid alum (8 % Al₂O₃) applied at a rate of 0.88:1 [Al/ total phosphorus (TP)], (2) commercial-grade liquid ferric chloride (38 % FeCl₃) applied at a rate of 0.89:1 [Fe/TP] and (3) commercial-grade liquid poly-aluminium chloride (10 % Al₂O₃) applied at a rate of 0.72:1 [Al/TP]. Results showed that an increased TI between slurry application and rainfall led to decreased P and SS losses in runoff, confirming that the prohibition of land-spreading slurry if heavy rain is forecast in the next 48 h is justified. Averaged over the three TIs, the addition of amendment reduced all types of P losses to concentrations significantly different (p?<?0.05) to those from unamended slurry, with no significant difference between treatments. Losses from amended slurry with a TI of 12 h were less than from unamended slurry with a TI of 48 h, indicating that chemical amendment of slurry may be more effective at ameliorating P loss in runoff than current TI-based legislation. Due to the high cost of amendments, their incorporation into existing management practices can only be justified on a targeted basis where inherent soil characteristics deem their usage suitable to receive amended slurry.     

Spatial and temporal trend of Chinese manure nutrient pollution and assimilation capacity of cropland and grassland

Dynamics of livestock and poultry manure nutrient was analyzed at a provincial scale from 2002 to 2008. The nutrient capacity of 18 kinds of croplands and grasslands to assimilate nutrients was assessed in the same temporal–spatial scale. Manure nitrogen (N) had increased from 5.111 to 6.228 million tons (MT), while manure phosphorus (P) increased from 1.382 to 1.607 MT. Manure N and P share similar spatial patterns of yields, but proportion of specialized livestock husbandry and contribution of leading livestock categories (swine, cattle, cow, sheep, layer chicken, broiler chicken) were different. The nutrients generated from dominant seven provinces took more than about half of total manure N in China. After subtracting the chemical fertilizers, there were some manure nutrient capacities in western part of China. Risk analysis of manure nutrient pollution overload in eastern and southern parts of China was serious, which should restrict livestock's developments. Amount of chemical fertilizers applied should be reduced to make room for manure nutrients. For the sake of greenhouse effects, the emission of methane (CH₄) and nitrous oxide (NO _x ) emissions in China is serious for the global change, thus merits further statistics and studies. The spatial and temporal pattern of Chinese manure nutrient pollution from livestock and the assimilation capacity of cropland and grassland can provide useful information for policy development on Chinese soil environment and livestock.     

Impacts of feedlot floor condition,deposition frequency,and inhibitors on N2O and CH4 emissions from feedlot dung and urine patches

Patches of dung and urine are major contributors to the feedlot gas emissions. This study investigated the impacts of dung deposition frequency (partly reflecting animal stocking density of a feedlot), dairy feedlot floor conditions (old floor indicated with the presence of consolidated manure pad [CMP] vs. new floor with the absence of consolidated manure pad [CMPn]), and application of dicyandiamide (DCD) and hydroquinone (HQ) on nitrous oxide (N₂O) and methane (CH₄) emissions from patches in the laboratory, and the integrative impacts were expressed in terms of global warming potential (CO₂-equivalent). Dung deposition frequency, feedlot floor condition, and application of inhibitors showed inverse impacts on N₂O and CH₄ emissions from patches. Greenhouse gas (GHG) emissions from the dung, urine, and dung+urine patches on the CMP feedlot surface were approximately 7.48, 87.35, and 7.10 times those on the CMPn feedlot surface (P < 0.05). Meanwhile, GHG emissions from CMP and CMPn feedlot surfaces under high deposition frequency condition were approximately 10 and 1.7 times those under low-frequency condition. Moreover, application of HQ slightly reduced the GHG emission from urine patches, by 14.9% (P > 0.05), while applying DCD or DCD+HQ significantly reduced the GHG, by 60.3% and 65.0%, respectively (P < 0.05). Overall, it is necessary to include feedlot management such as animal stocking density and feedlot floor condition to the process of determining emission factors for feedlots. In the future, field measurements to quantitatively evaluate the relative contribution of nitrification and denitrification to the N₂O emissions of feedlot surfaces are highly required for effective N₂O control.

Implications: This study shows that feedlot CH₄ and N₂O emissions inversely respond to the dicyandiamide (DCD) application. Applying DCD significantly reduces GHG emissions of feedlot urine patches. Feedlot floor condition and stocking density strongly impact feedlot GHG emissions. Including feedlot floor condition and stocking density in the feedlot EF determining process is necessary.     

Regional and sectoral assessment of greenhouse gas emissions in India

In this paper the authors have estimated for 1990 and 1995 the inventory of greenhouse gases CO₂, CH₄ and N₂O for India at a national and sub-regional district level. The district level estimates are important for improving the national inventories as well as for developing sound mitigation strategies at manageable smaller scales. Our estimates indicate that the total CO₂, CH₄ and N₂O emissions from India were 592.5, 17, 0.2 and 778, 18, 0.3 Tg in 1990 and 1995, respectively. The compounded annual growth rate (CAGR) of these gases over this period were 6.3, 1.2 and 3.3%, respectively. The districts have been ranked according to their order of emissions and the relatively large emitters are termed as hotspots. A direct correlation between coal consumption and districts with high CO₂ emission was observed. CO₂ emission from the largest 10% emitters increased by 8.1% in 1995 with respect to 1990 and emissions from rest of the districts decreased over the same period, thereby indicating a skewed primary energy consumption pattern for the country. Livestock followed by rice cultivation were the dominant CH₄ emitting sources. The waste sector though a large CH₄ emitter in the developed countries, only contributed about 10% the total CH₄ emission from all sources as most of the waste generated in India is allowed to decompose aerobically. N₂O emissions from the use of nitrogen fertilizer were maximum in both the years (more than 60% of the total N₂O). High emission intensities, in terms of CO₂ equivalent, are in districts of Gangetic plains, delta areas, and the southern part of the country. These overlap with districts with large coal mines, mega power plants, intensive paddy cultivation and high fertilizer use. The study indicates that the 25 highest emitting districts account for more than 37% of all India CO₂ equivalent GHG emissions. Electric power generation has emerged as the dominant source of GHG emissions, followed by emissions from steel and cement plants. It is therefore suggested, to target for GHG mitigation, the 40 largest coal-based thermal plants, five largest steel plants and 15 largest cement plants in India as the first step.     

Ammonia abatement and its impact on emissions of nitrous oxide and methane—Part 2: application for Europe

Agriculture is an important source of NH₃, which contributes to acidification and eutrophication, as well as emissions of the greenhouse gases CH₄ and N₂O. Because of their common sources, emission reduction measures for one of these gases may affect emissions of others. These interrelations are often ignored in policy making. This study presents an analysis of the effects of measures to reduce NH₃ emissions on emissions of N₂O and CH₄ from agriculture in Europe. The analysis combines information from the NH₃ module of the Regional Air pollution INformation and Simulation (RAINS) model for Europe with the IPCC method for national greenhouse gas inventories. The IPCC method for estimating agricultural emissions of N₂O and CH₄ is adjusted in order to use it in combination with the RAINS database for the European agricultural sector. As an example, we applied the adjusted method to the agricultural sector in the Netherlands and found that application of several NH₃ abatement options may result in a substantial increase in N₂O emissions while the effect on CH₄ emissions is relatively small. In Part 2 of this paper we focus on the resulting emissions for all European countries for 1990 and 2010.     

Gaseous emission during the composting of pig feces from Chinese Ganqinfen system

The Ganqinfen system – a process of manually cleaning animal feces by means of a shovel – is a widely used manure separating method in Chinese pig farms. Ganqinfen pig feces and chopped corn stalks were mixed at the ratio of 7:1, and composted in 1.5 m³ rotting boxes for 70 d. Evolution of CH₄, N₂O and NH₃ during composting, and the effects of turning and covering, were studied in this research. Results showed that 20–39% and 0.5–4% of total nitrogen were lost in the form of NH₃ and N₂O respectively, and 0.1–0.9% of initial organic carbon was emitted as CH₄. Turning enhanced air exchange in the piles, thus decreasing CH₄ emission by 83–93% and shortening the maturing period. When trials were finished, all non-turned piles were separated to three layers by moisture content. This structure caused the N₂O losses of non-turning treatments to be 6–12.7 times higher than that of turning treatments. Covering materials reduced air exchange at the surface of the pile, thus decreasing the O₂ supply and consequently increasing CH₄ production by 33–45%. Covering also reduced NH₃ emission by 4–34%. For the composting of Ganqinfen pig feces, we suggest that a program of turning twice weekly without covering will result in compost that is sufficiently matured after 6 wk with the lowest resultant greenhouse gas emission.     

Characterisation of soil emissions of nitric oxide at field and laboratory scale using high resolution method

Agricultural soils may account for 10% of anthropogenic emissions of NO, a precursor of tropospheric ozone with potential impacts on air quality and global warming. However, the estimation of this biogenic source strength and its relationships to crop management is still challenging because of the spatial and temporal variability of the NO fluxes.Here, we present a combination of new laboratory- and field-scale methods to characterise NO emissions and single out the effects of environmental drivers.First, NO fluxes were continuously monitored over the growing season of a maize-cropped field located near Paris (France), using 6 automatic chambers. Mineral fertilizer nitrogen was applied from May to October 2005. An additional field experiment was carried out in October to test the effects of N fertilizer form on the NO emissions. The automatic chambers were designed to measure simultaneously the NO and N₂O gases. Laboratory measurements were carried out in parallel using soil cores sampled at same site to test the response of NO fluxes to varying soil N–NH₄ and water contents, and temperatures. The effects of soil core thickness were also analysed.The highest NO fluxes occurred during the first 5 weeks following fertilizer application. The cumulative loss of NO–N over the growing season was estimated at 1.5 kg N ha^?1, i.e. 1.1% of the N fertilizer dose (140 kg N ha^?1). All rainfall events induced NO peak fluxes, whose magnitude decreased over time in relation to the decline of soil inorganic N. In October, NO emissions were enhanced with ammonium forms of fertilizer N. Conversely, the application of nitrate-based fertilizers did not significantly increase NO emissions compared to an unfertilized control. The results of the subsequent laboratory experiments were in accordance with the field observations in magnitude and time variations. NO emissions were maximum with a water soil content of 15% (w w^?1), and with a NH₄–N content of 180 mg NH₄–N kg soil^?1. The response of NO fluxes to soil temperature was fitted with two exponential functions, involving a Q₁₀ of 2.0 below 20 °C and a Q₁₀ of 1.4 above. Field and laboratory experiments indicated that most of the NO fluxes originated from the top 10 cm of soil. The characterisation of this layer in terms of mean temperature, NH₄ and water contents is thus paramount to explaining the variations of NO fluxes.     

A field trial of nutrient stimulation of methanotrophs to reduce greenhouse gas emissions from landfill cover soils

Landfills are among the major sources of anthropogenic methane (CH₄) estimated to reach 40?×?10⁹kg per year worldwide by 2015 (IPCC, 2007 IPCC. 2007. Intergovernmental Panel on Climate Change, Synthesis Report on Contributions of Work Groups 1, 2, and 3 to the Fourth Assessment Report Core Writing Team, Edited by: Pauchar, R.K. and Reisinger, A. Geneva, Switzerland: IPCC.  [Google Scholar]). A 2½-year field experiment was conducted at a closed landfill in western Michigan where methanotrophs, methane-consuming bacteria, were stimulated by nutrient addition to the soil without significantly increasing biogenic nitrous oxide (N₂O) production. The effects of the nitrogen amendments (KNO₃ and NH₄Cl), phenylacetylene (a selective inhibitor of nitrifying bacteria that contribute to N₂O production), and a canopy (to reduce direct water infiltration) on the vertical soil gas profiles of CH₄, CO₂, and O₂ were measured in the top meter of the soil. Methane and nitrous oxide fluxes were calculated from the corresponding soil gas concentration gradients with respect to depth and a Millington–Quirk diffusivity coefficient in soil derived empirically from soil porosity, water content, and diffusivity coefficients in air from the literature. Methane flux estimates were as high as 218.4 g m^?2 day^?1 in the fall and 12.8 g/m^?2 day^?1 in the summer. During the spring and summer, CH₄ fluxes were reduced by more than half by adding KNO₃ and NH₄Cl into the soil as compared to control plots, while N₂O fluxes increased substantially. The concurrent addition of phenylacetylene to the amendment decreased peak N₂O production by half and the rate of peak methane oxidation by about one-third. The seasonal average methane and N₂O flux data were extrapolated to estimate the reduction of CH₄ and N₂O fluxes into the atmosphere by nitrogen and inhibitor addition to the cover soils. The results suggest that such additions coupled with soil moisture management may provide a potential strategy to significantly reduce greenhouse gas emissions from landfills.

Implications The results of a 2½-year study of effects of nutrient stimulation on methane oxidation in landfill cover soils demonstrates that nutrient addition does decrease methane emissions. The work further underscores the control which soil moisture exerts on methane oxidation. Water management is critical to the success of methane oxidation strategies.