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Summary Anaerobic digesters produce biogas, a mixture of predominantly CH4 and CO2, which is typically incinerated to recover electrical and/or thermal energy. In a context of circular economy, the CH4 and CO2 could be used as chemical feedstock in combination with ammonium from the digestate. Their combination into protein‐rich bacterial, used as animal feed additive, could contribute to the ever growing global demand for nutritive protein sources and improve the overall nitrogen efficiency of the current agro‐ feed/food chain. In this concept, renewable CH4 and H2 can serve as carbon‐neutral energy sources for the production of protein‐rich cellular biomass, while assimilating and upgrading recovered ammonia from the digestate. This study evaluated the potential of producing sustainable high‐quality protein additives in a decentralized way through coupling anaerobic digestion and microbial protein production using methanotrophic and hydrogenotrophic bacteria in an on‐farm bioreactor. We show that a practical case digester handling liquid piggery manure, of which the energy content is supplemented for 30% with co‐substrates, provides sufficient biogas to allow the subsequent microbial protein as feed production for about 37% of the number of pigs from which the manure was derived. Overall, producing microbial protein on the farm from available methane and ammonia liberated by anaerobic digesters treating manure appears economically and technically feasible within the current range of market prices existing for high‐quality protein. The case of producing biomethane for grid injection and upgrading the CO2 with electrolytic hydrogen to microbial protein by means of hydrogen‐oxidizing bacteria was also examined but found less attractive at the current production prices of renewable hydrogen. Our calculations show that this route is only of commercial interest if the protein value equals the value of high‐value protein additives like fishmeal and if the avoided costs for nutrient removal from the digestate are taken into consideration., Anaerobic digesters are the core engine for a biorefinery producing microbial protein. Either the biogas can be used directly for its production, or via biogas upgrading the separate CO2 can be combined with electrolytic hydrogen to produce more protein.

In this study, the anaerobic performance and stability of coffee husk and pulp with and without trace element (TE) supplement was investigated, using 20 L mesophilic continuous stirred tank reactors for 140 days of experiment (DOE). The TE was cocktail of trace metals composed of Fe, Ni, Zn, Co, Mn, Mo, Se W and B. The organic loading rate (OLR) was increased stepwise from 2.5 (HRT = 40 d) to 6.0 kg VS m(−3) d(− 1)(HRT = 16.7 d). The highest methane productivity from pulp with and without TE was 1.272 and 0.965 m(3) m(−3) d(−1) at an OLR of 6.0 and 5.0 kg VS m(−3) d(−1); while the husks performed 0.895 and 0.795 m(3) m(−3) d(−1) respectively, both at an OLR of 6.0 kg VS m(−3) d(−1). The specific methane yield (SMY) of pulp (at OLR = 5 kg VS m(−3) d(−1)) with and without TEs was 217.9 ± 4.7 and 193.1 ± 8.2 L kg(−1 )VS; while husk yielded 149.2 ± 6.0 and 132.5 ± 4.9 L kg(−1 )VS, respectively. The effect of TEs on SMY was statistically significant (p

Composting of beef cattle manure using sawdust or recycled compost as a bulking agent was investigated for the management of clopyralid risk, such as changes in the clopyralid concentration and the mechanism of clopyralid accumulation caused by recycled compost. These raw materials were composted with laboratory equipment, which was controlled at 60℃ after the temperature peak by autothermal composting. Clopyralid concentration did not changed during composting in the thermophilic phase; on the contrary, it increased because clopyralid accumulated in compost when recycled compost was used repeatedly as a bulking agent. The clopyralid accumulation ratio (ratio of clopyralid concentration to that in the first compost) could be explained by a model using a recurrence formula, and a correlation existed between the calculated (model) accumulation ratios and measured accumulation ratios (R2 = 0.78). Using this model, the excessive accumulation of clopyralid could be controlled when using recycled compost as a bulking agent with lower moisture content or when part of the recycled compost was replaced by another bulking agent, even if recycled compost had high moisture content. In future work, the model and its considerations should be verified in a field test.

Ekinci, Kamil/0000-0002-7083-5199 Composting plants should be operated at a high degradation rate in order to lower their capital and operational costs. Initial C/N ratio is one of the most influential factors on the composting process. This study aimed to determine the impacts of initial C/N ratio on operational composting parameters of two-phase olive mill pomace with separated dairy manure. Five initial C/N ratios ranging from 29.43 to 43.33 were examined using fifteen 100 L cylindrical reactors. The highest decomposition rate was estimated at 0.02 day(-1)with the C/N ratio of 34.49. The maximum relative heat generation was obtained with the C/N ratio of 36.07. The C/N ratio of approximately equal to 33 reduced the composting cost of process-based total airflow supplied per dry matter and organic matter loss. The maximum throughput capacity was obtained when the compost blend had the C/N ratio of approximately equal to 37.24. It was concluded that operating the composting of two-phase olive mill waste, separated dairy manure, and straw with the boundary of the initial C/N ratios between 33 and 37 was recommended. Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [KAMAG111G055/111G149] Scientific and Technological Research Council of Turkey, Grant/Award Number: KAMAG111G055/111G149

Emission of odorous and toxic gases from stored livestock manure is well documented and poses a serious health risk to farmers and livestock. Hydrogen sulfide emissions have been sharply rising with increasingly intensive livestock production and are of particular concern because of the acute toxicity of this gas. Numerous strategies, technologies, and chemical treatments have been used to control hydrogen sulfide emissions, but none have worked particularly well because they are neither cost-effective nor environmentally sustainable, or they are too toxic for animals. The inhibitory effect of the sodium tetraborate decahydrate (i.e., borax) treatment to reduce hydrogen sulfide production using sulfate-reducing bacteria was examined in shallow manure pits in a starter-grower swine facility. Monitoring of air emissions and DNA analysis revealed that treatment of stored swine manure effectively reduced hydrogen sulfide production, and the reduction correlated to a decrease in the sulfate-reducing bacteria population in the stored swine manure.

peer-reviewed Carbon (C) losses from agricultural soils to surface waters can migrate through water treatment plants and result in the formation of disinfection by-products, which are potentially harmful to human health. This study aimed to quantify total organic carbon (TOC) and total inorganic C losses in runoff after application of dairy slurry, pig slurry, or milk house wash water (MWW) to land and to mitigate these losses through coamendment of the slurries with zeolite (2.36 3.35 mm clinoptilolite) and liquid polyaluminum chloride (PAC) (10% Al2O3) for dairy and pig slurries or liquid aluminum sulfate (alum) (8% Al2O3) for MWW. Four treatments under repeated 30-min simulated rainfall events (9.6 mm h-1) were examined in a laboratory study using grassed soil runoff boxes (0.225 m wide, 1 m long; 10% slope): control soil, unamended slurries, PAC-amended dairy and pig slurries (13.3 and 11.7 kg t-1, respectively), alum-amended MWW (3.2 kg t-1), combined zeolite and PAC-amended dairy (160 and 13.3 kg t-1 zeolite and PAC, respectively) and pig slurries (158 and 11.7 kg t-1 zeolite and PAC, respectively), and combined zeolite and alumamended MWW (72 and 3.2 kg t-1 zeolite and alum, respectively). The unamended and amended slurries were applied at net rates of 31, 34, and 50 t ha-1 for pig and dairy slurries and MWW, respectively. Significant reductions of TOC in runoff compared with unamended slurries were measured for PACamended dairy and pig slurries (52 and 56%, respectively) but not for alum-amended MWW. Dual zeolite and alum-amended MWW significantly reduced TOC in runoff compared with alum amendment only. We conclude that use of PAC-amended dairy and pig slurries and dual zeolite and alum-amended MWW, although effective, may not be economically viable to reduce TOC losses from organic slurries given the relatively low amounts of TOC measured in runoff from unamended slurries compared with the amounts applied. ACCEPTED peer-reviewed

Ulgudur, Nilufer/0000-0003-3410-0598 WOS: 000462970500008 PubMed: 30624833 Although anaerobic digestion is a well-established technology, the treatment and disposal of the digestate still presents a challenge due to lack of viable methods for processing. The residual organic matter in digestates also creates a significant residual biogas potential. This fact indicates that the digestates need further processing not only to reduce their organic content for disposal, but also to capture the biogas associated with this residual organic content. This study investigated anaerobic treatment and residual biogas potential of digestates obtained from five full-scale farm-based digesters. The results indicated that it was possible to reduce the total chemical oxygen demand (CODt) of the digestates with an efficiency of 21%-84%. The corresponding biogas yields of digestates ranged between 0.078 and 0.326 L-biogas/g VSadded. This level of biogas production is comparable to the biogas production potential of several commonly used raw substrates.(C) 2019 Water Environment Federation Office of Scientific Research Projects Coordination of Middle East Technical University [BAP-03-11-2016-002] This study was supported by Office of Scientific Research Projects Coordination of Middle East Technical University [BAP-03-11-2016-002].

Composting process parameters such as C/N ratio, moisture content, and temperature are well studied, but limited knowledge exists on energy consumption of the process itself. In this study, co-composting of rose oil-processing wastes (ROPW) with caged layer manure and straw was performed to optimize the system in terms of energy use. Intermittent aeration applied to the five compost mixtures with initial C/N ratios of 12.81, 21.37, 24.66, 29.22, and 37.41 was conducted using fifteen identical cylindrical reactors with volume of 60 L. O2 and CO2 concentrations, compost temperature, dry matter loss, organic matter loss, electrical conductivity, and pH were measured. A first-order kinetic model based on material mass balance was applied to determine kinetic parameters such as decomposition rate and compost equilibrium mass. An equation describing specific energy per initial dry mass of composting as a function of initial C/N ratio was presented and used to optimize initial C/N ratio to maximize composting of ROPW to reach a given level of compost mass ratio. The maximum decomposition, based on dry matter loss, occurred at the initial C/N ratio of 30.18 was 0.032 kg kg−1 day−1. Initial C/N ratio to minimize specific energy use of ROPW composting with caged layer to reach a given level of compost ratio of 0.82 was 29.11. Composting operation can be performed at this initial C/N ratio (29.11) to minimize airflow to keep the power requirement low while still operating the system efficiently. This helps to reduce the energy required for ROPW composting with caged layer to reach a given compost mass ratio. © 2016 American Institute of Chemical Engineers Environ Prog, 2016

Additives applied to animal manure slurries can affect the chemical composition and the biological processes of slurries during storage, with possible improvement of their management and reduction of environmental problems. Some new formulations are marketed claiming a nitrogen (N) removal effect due to denitrification, with the consequence of a reduced N content in the manure after storage. This study evaluated the effects of one of these commercial additives (BACTYcomplex) on slurry characteristics and N losses at a commercial piggery. The additive was applied to four different sectors of the piggery, each with an independent under-floor slurry pit; four other sectors served as controls without treatment. Pits were emptied every 4 wk, and the manure was analyzed for total and ammonia-N and total and volatile solids. Slurry samples from the last month of the on-farm assessment were removed and stored thermostatically in vessels external to the piggery. A subsample of slurry that was treated with the additive at the piggery was treated with an additional dose of additive at the beginning of long-term storage. The additive did not change the composition of the slurry during in-house storage (4 wk duration). During the 155 d of external thermostatic storage, the total solids content of treated slurry was reduced by 18% compared with control slurry, but the N content and composition of treated slurry was unaffected. The additive had a positive effect in accelerating the stabilization of the slurry but did not modify N losses.

Solid-liquid separation is performed to improve slurry management, and acidification of the slurry is used to reduce ammonia emissions. Acidification is known to affect slurry characteristics, and we hypothesized that it may affect mechanical separation. Our objective in this study was to assess the effects of slurry acidification on particle size distribution and separation efficiency. Two types of slurry, aged pig and fresh dairy, and two different acidification additives, sulfuric acid and aluminum sulfate (alum), were studied. We found that acidification with sulfuric acid promoted phosphorus (P) solubilization for both slurries, but no change was observed with alum. More ammonium was found in the acidified dairy slurry compared with raw dairy slurry, but no difference was found in aged pig slurry. Acidification before separation increased the proportion of the solid fraction in the slurries, and the effect was significantly higher with alum. When alum was used to acidify the slurries, the proportion of particles larger than 100 μm increased significantly, as did the P concentration in this particle size range. The efficiency of P separation increased markedly in both slurries when alum was used, with the removal to the solid fraction of the dairy slurry being almost complete (90%). Because the priority in mechanical separation is to increase the P content in the solid fraction, the use of alum before centrifugation may be the most suitable option for enhancing its nutrient content. We conclude that separation efficiency and particle size distribution are significantly affected by acidification, but the extent of the effects depends on slurry type and on the type of additive used for acidification.

BACKGROUND Microbial fuel cells (MFCs) directly convert the chemical energy present in wastewater into electricity. Enriching exoelectrogenic bacteria in the anode biofilm is a current and challenging research target. A multiparametric control strategy, focused on organic loading rate (OLR) and external resistance (Rext) parameters, is here proposed to enhance microbial selection in MFCs. RESULTS The study examines the performance of a swine manure fed MFC working at optimal electrical condition. Maximum power point tracking (MPPT) control was adopted to continuously optimize applied Rext. Subsequent OLR decreases were performed to gradually improve anodic biofilm exoelectrogenic activity. The study demonstrates that high OLRs (11.2 kg COD m−3 d−1) limit MFC electrochemical losses, and increase absolute values of organic removal rate (4.6 kg COD m−3 d−1) and current production (14.9 mA). On the other hand, low OLR adoption (0.7 kg COD m−3 d−1) results in higher organic matter removal (52%) and coulombic efficiency (higher than 70%) of the MFC. CONCLUSION A multiparametric control for MFCs is proposed. Combining MPPT control and low OLR results in rapid improvement of exoelectrogenic activity in MFCs biofilm. The developed strategy may be useful for future MFCs applications, in order to achieve efficient start-up and sustainable operation. © 2015 Society of Chemical Industry

BACKGROUND In 2012, 9.3 million head of dairy cows in the USA produced an estimated 20 million metric tons of manure solids, but little value was gained from this manure. There is a pressing need to enhance manure resource recovery efforts, as dairy manure has potentially significant environmental impacts. This study evaluated components of an integrated suite of biological processes designed to maximize resource recovery from dairy manure, in which algae grown on polyhydroxyalkanoate (PHA) production effluent (PHA-algae) were fermented and anaerobically digested to determine process impacts. RESULTS A 10% PHA-algae supplement produced 11% more volatile fatty acids (VFA) during fermentation and 11% more methane during anaerobic digestion (AD) (vs. dairy manure); the PHA-algae biogas also contained a higher percentage (62.7 vs. 59.1%) of methane than manure biogas. Algal augmentation exhibited no negative effect on fermenter or AD operation. Quantitative polymerase chain reaction (PCR) showed that the ADs contained substantial populations of both acetoclastic and hydrogenotrophic methanogens, which, given the heterogeneous substrate, enhanced process stability. There were significant differences between PHA-algae batches, and large quantities of COD were released during algae freezing. CONCLUSION PHA-algae yielded more VFA during fermentation, and a more methane-rich biogas following AD than dairy manure. A 10% PHA-algae supplement caused no process disturbance in normal manure flora. © 2015 Society of Chemical Industry

Obtaining a reliable estimation of the methane potential of organic waste streams in anaerobic digestion, for which a biochemical methane potential (BMP) test is often used, is of high importance. Standardization of this BMP test is required to ensure inter-laboratory repeatability and accuracy of the BMP results. Therefore, guidelines were set out; yet, these do not provide sufficient information concerning origin of and the microbial community in the test inoculum. Here, the specific contribution of the methanogenic community on the BMP test results was evaluated. The biomethane potential of four different substrates (molasses, bio-refinery waste, liquid manure and high-rate activated sludge) was determined by means of four different inocula from full-scale anaerobic digestion plants. A significant effect of the selected inoculum on the BMP result was observed for two out of four substrates. This inoculum effect could be attributed to the abundance of methanogens and a potential inhibiting effect in the inoculum itself, demonstrating the importance of inoculum selection for BMP testing. We recommend the application of granular sludge as an inoculum, because of its higher methanogenic abundance and activity, and protection from bulk solutions, compared with other inocula.

Nitrous oxide (N2O), ammonia (NH3), and methane (CH4) emissions from the manure management chain of livestock production systems are important contributors to greenhouse gases (GHGs) and NH3 emitted by human activities. Several studies have evaluated manure-related emissions and associated key variables at regional, national, or continental scales. However, there have been few studies focusing on the drivers of these emissions using a global dataset. An international project was created (DATAMAN) to develop a global database on GHG and NH3 emissions from the manure management chain (housing, storage, and field) to identify key variables influencing emissions and ultimately to refine emission factors (EFs) for future national GHG inventories and NH3 emission reporting. This paper describes the “field” database that focuses on N2O and NH3 EFs from land-applied manure and excreta deposited by grazing livestock. We collated relevant information (EFs, manure characteristics, soil properties, and climatic conditions) from published peer-reviewed research, conference papers, and existing databases. The database, containing 5,632 observations compiled from 184 studies, was relatively evenly split between N2O and NH3 (56 and 44% of the EF values, respectively). The N2O data were derived from studies conducted in 21 countries on five continents, with New Zealand, the United Kingdom, Kenya, and Brazil representing 86% of the data. The NH3 data originated from studies conducted in 17 countries on four continents, with the United Kingdom, Denmark, Canada, and The Netherlands representing 79% of the data. Wet temperate climates represented 90% of the total database. The DATAMAN field database is available at http://www.dataman.co.nz.

The concept of symbiosis, a mutually beneficial relationship, can be applied to food and energy systems. Greenhouse systems and biogas plants are interesting technologies for food–energy symbiosis, because both are usually based in rural areas and offer opportunities for the exchange of materials (e.g., biomass waste from the greenhouse as input to biogas plants) and energy (heat from biogas co‐generation for heating greenhouses). In this paper, the focus lies on manure resources for biogas in Switzerland, because manure amounts are high and currently largely underused. We provide a spatial analysis of the availability of manure as feedstock to biogas plants and heat source for greenhouses. In this feasibility study, we coupled the potential waste heat supply from manure‐based biogas and the greenhouse peak heat demand. We quantified the area‐based greenhouse heating demand for year‐around tomato production (from 0.98 to 2.67 MW ha−1 where the farms are located) and the available heat supply from manure‐based biogas (up to 3,200 GJ a−1 km−2). A total maximum greenhouse area of 104 ha could be sustained with manure‐based biogas heat, producing 20,800 tonnes a−1 tomatoes. This amounts to 11% of the total domestic tomato demand. Although the results are specific to Switzerland, our method can be adapted and also applied to other regions.

Biogas production on dairy farms is promoted as a climate change measure since it captures methane, a greenhouse gas emitted by manure, and produces renewable energy. Digestate is a by-product of biogas production and is often used for nutrient recycling in a similar way as traditional manure. Despite having similar functions, manure and digestate have different behaviors related to nitrogen recycling and nitrogen emissions which are significant agricultural and environmental concerns of manure. This paper provides an insight into the impact of biogas production on nitrogen emissions and nitrogen recycling issues of the current dairy farming practice. Using the Substance Flow Analysis (SFA) approach, we analyzed the changes on three levels: manure handling, dairy farm, and the whole chain. Four biogas production options on a Dutch dairy farm related to types and sources of feedstocks were considered. We quantified biogas output, nitrogen fertilizer replacement percentage (%) and consequential nitrogen emissions (kgN/year; kgN/m(3) biogas produced) of these productions in comparison with the baseline of current dairy farming without biogas. We conclude that biogas production options with additional feedstocks will cause profound changes in the nitrogen recycling on dairy farms and the nitrogen emissions at the chain level. Besides, the results show that determining the optimal biogas production option can be challenging as the evaluation is highly dependent on the used nitrogen indicator and the included level of analysis. Our findings show how SFA and a multilevel perspective can give a broader understanding of environmental trade-offs.

10 páginas.-- 1 figuras.-- 9 tablas.-- 47 referencias, In semi-arid Mediterranean soils, water availability is the most limiting factor, negatively affecting the organic matter (OM) degradation. The aim of this work is to study under controlled laboratory conditions how three sources of OM [municipal solid waste (MSW), sheep manure (SM) and cow manure (CM)] behave when they are applied to an agricultural soil subjected to a severe year-long drought. In order to apply the same concentration of OM to the soil (16·92 Mg OM ha), 2 kg of soil was mixed with 30, 67·41 and 55·25 Mg ha (dry matter) of MSW, CM and SM, respectively. Two levels of irrigation were employed: (i) watered soils and (ii) non-watered soils. Soil's chemical properties [water soluble carbon (WSC), humic acids, fulvic acids and protein mass distribution], biological properties (soil microbial biomass carbon and o-diphenoloxidase activity) and solid-state C cross-polarisation magic angle spinning nuclear magnetic resonance spectroscopy were determined. In watered soils, the soil microbial biomass carbon was higher in the SM than in CM and MSW treatments (9·9% and 23·1%, respectively). The WSC was significantly higher in SM than in CM (55·7%) and MSW (78·7%) treatments. A decrease in the content of O-alkyl C and an increase in alkyl C, aromatic C and carboxyl C were observed. In non-watered soils, the biochemical properties and alkyl C and alkyl/O-alkyl ratio decreased, whereas WSC content and O-alkyl C increased. These results indicated that the evolution of OM and the activity of the microbial community in non-watered soils were very different to those in the watered soils. Copyright © 2016 John Wiley & Sons, Ltd., This study was funded by the University of Seville (Spain).Also, this paper has benefited from the comments of anony-mous referees

Although it is widely agreed that stocking density critically affects the rate of vermicomposting, there is no established stocking density for mixtures of fly ash and other waste materials. This study sought to optimize (Savigny, 1826) stocking density for effective biodegradation and nutrient release in a fly ash-cow dung-waste paper (FCP) mixture. Four stocking densities of 0, 12.5, 25, and 37.5 g worms kg were evaluated. Although the 12.5, 25, and 37.5 g worms kg treatments all resulted in a mature vermicompost, stocking densities of 25 and 37.5 g worms kg resulted in faster maturity, higher humification parameters, and a significantly lower final C/N ratio (range 11.1-10.4). The activity of β-glucosidase and fluorescein diacetate hydrolysis enzymes showed faster stabilization at stocking densities of 25 and 37.5 g worms kg, indicating compost stability and maturity. Similarly, a stocking density of 25 g worms kg resulted in the highest release of Olsen-extractable P and (NO + NO)-N contents. The 0-, 12.5-, 25-, and 37.5-g treatments resulted in net Olsen P increases of 16.3, 38.9, 61.0, and 53.0%, respectively, after 10 wk. Although compost maturity could be attained at stocking densities of 12.5 g worms kg, for faster production of humified and nutrient-rich FCP vermicompost, a stocking density of 25 g worms kg seems most appropriate.

Summary Biogas residues contain microbial biomass, which contributes to the formation of soil organic matter. Whether the potential of biogas residues to increase soil organic matter can be enhanced by co-application with compost, biochar or manure is unknown, however. The aim of this paper is to evaluate the effects of co-amendment on the mineralization of biogas residues, carbon dioxide emissions and the carbon flow within the microbial food web. We determined the fate of 13C-labelled microbial biomass present in biogas residues applied together with compost, biochar and manure to soil, by analysing CO2 and biomarker phospholipid fatty acids. Although the rate of mineralization constant of the slowly degrading carbon pool was not affected by co-amendments, co-amendment with manure resulted in a larger rate of mineralization constant of the readily degrading carbon pool of biogas residues. The incorporation of carbon was mainly to Gram-negative biomass and was the smallest with manure co-amendment, which indicated differences in bioavailability of the carbon source.

Mine-soil treatment using stabilized manure rapidly sequesters large quantities of organic carbon and nutrients. However, the nutrient-rich soil conditions may become highly conducive for production and emission of N2O. We examined this possibility in a Pennsylvania coal mine restored using poultry manure stabilized in two forms: composted (Comp) or mixed with paper mill sludge (Man + PMS) at C/N ratios of 14, 21, and 28 and compared those with the emissions from conventionally treated soil. The mine soil was extremely well drained with 59% coarse fragments. Soil–atmosphere exchange of N2O and CO2 was determined using a sampling campaign of ten measurements between 16 June and 14 September 2009 (90 days) and 13 measurements between 28 June and 9 November 2010 (134 days) using static vented chambers at ambient and increased moisture (water added) content. Potential denitrification was determined in a laboratory incubation experiment. While non-amended mine soil did not have a measurable potential for denitrifying activity, the manure-based amendments introduced the potential. Soil water filled pore space was less than 60% on most sampling days in both ambient and water-added plots. Daily N2O-N emissions ranged between 40 and 70 g N ha−1 with cumulative emissions of 2–4 kg N ha−1 from non-amended, lime and fertilizer (L + F) and Comp, and 3–10 kg N ha−1 from Man + PMS treatments. The maximum emission obtained from Man + PMS represented

Biochar as a carbon-rich coproduct of pyrolyzing biomass, its amendment has been advocated as a potential strategy to soil carbon (C) sequestration. Updated data derived from 50 papers with 395 paired observations were reviewed using meta-analysis procedures to examine responses of soil carbon dioxide (CO2) fluxes, soil organic C (SOC), and soil microbial biomass C (MBC) contents to biochar amendment. When averaged across all studies, biochar amendment had no significant effect on soil CO2 fluxes, but it significantly enhanced SOC content by 40% and MBC content by 18%. A positive response of soil CO2 fluxes to biochar amendment was found in rice paddies, laboratory incubation studies, soils without vegetation, and unfertilized soils. Biochar amendment significantly increased soil MBC content in field studies, N-fertilized soils, and soils with vegetation. Enhancement of SOC content following biochar amendment was the greatest in rice paddies among different land-use types. Responses of soil CO2 fluxes and MBC to biochar amendment varied with soil texture and pH. The use of biochar in combination with synthetic N fertilizer and waste compost fertilizer led to the greatest increases in soil CO2 fluxes and MBC content, respectively. Both soil CO2 fluxes and MBC responses to biochar amendment decreased with biochar application rate, pyrolysis temperature, or C/N ratio of biochar, while each increased SOC content enhancement. Among different biochar feedstock sources, positive responses of soil CO2 fluxes and MBC were the highest for manure and crop residue feedstock sources, respectively. Soil CO2 flux responses to biochar amendment decreased with pH of biochar, while biochars with pH of 8.1–9.0 had the greatest enhancement of SOC and MBC contents. Therefore, soil properties, land-use type, agricultural practice, and biochar characteristics should be taken into account to assess the practical potential of biochar for mitigating climate change.

Livestock manures are major sources of nutrients, used for the fertilisation of cropland and grassland. Accurate estimates of the amounts of nutrients in livestock manures are required for nutrient management planning, but also for estimating nitrogen (N) budgets and emissions to the environment. Here we report on N excretion factors for a range of animal categories in policy reports by member states of the European Union (EU). Nitrogen excretion is defined in this paper as the total amount of N excreted by livestock per year as urine and faeces. We discuss the guidelines and methodologies for the estimation of N excretion factors by the EU Nitrates Directive, the OECD/Eurostat gross N balance guidebook, the EMEP/EEA Guidebook and the IPCC Guidelines. Our results show that N excretion factors for dairy cattle, other cattle, pigs, laying hens, broilers, sheep, and goats differ significantly between policy reports and between countries. Part of these differences may be related to differences in animal production (e.g. production of meat, milk and eggs), size/weight of the animals, and feed composition, but partly also to differences in the aggregation of livestock categories and estimation procedures. The methodologies and data used by member states are often not well described. There is a need for a common, harmonised methodology and procedure for the estimation of N excretion factors, to arrive at a common basis for the estimation of the production of manure N and N balances, and emissions of ammonia (NH3) and nitrous oxide (N2O) across the EU. © 2015 Society of Chemical Industry

Mine-land reclamation for biomass production is often achieved by means of large applications of N and organic C with amendments that could create soil conditions favorable for N2O production and emissions. To investigate this possibility, we conducted a laboratory experiment using mine soil collected from an active surface coal mine site near Philipsburg, Pennsylvania. During a 37-d incubation period, we measured N2O and CO2 fluxes from non-amended soil and from soil amended with ammonium nitrate (L + F), composted poultry manure (Comp), poultry manure alone (Man) and mixed with 3 rates of paper mill sludge (PMS) to obtain carbon to nitrogen ratios of 14, 20 and 27 (Man + PMS14, 20 and 27), each at 60% and 80% water filled pore space (WFPS). Results showed that manure alone leads to a greater emission of N2O under laboratory conditions than with L + F. However, composting manure effectively reduced the emissions compared to that of L + F despite a large addition of organic C and N. Composted manure-treated soil emitted less than all other manure-based treatments at both 60% and 80% WFPS. The emissions were greater from soil amended with the Man + PMS treatments compared to non-amended and L + F-amended soil, and it increased during periods of intense microbial activity created by the application of manure and PMS. Higher water content increased emissions particularly during periods of intense microbial activity coupled with inorganic N availability. Cumulative N2O emissions from manure-treated soils represented less than 0·1% loss of total applied N. Copyright © 2014 John Wiley & Sons, Ltd.

Indigenous traditional methods of saving and storing seeds are often seen as viable alternatives to purchasing hybridised seeds for small-scale farmers across the developing world. Nevertheless, little research has been conducted on which particular seed saving methods are most effective. Therefore, the purpose of this paper is to both document and test the efficacy of different traditional seed saving methods practiced by small-scale farmers in rural Malawi. Methods involved conducting both a survey and semi-structured interview with 40 small-scale farmers all of whom practiced different forms of traditional seed saving. A representative sample of sorghum and maize seeds were collected from each of these farms and grown in laboratory conditions to test the efficacy and germination rates of seeds stored using different practices. The results revealed that farmers used a wide range of indigenous seed saving techniques that include burning animal manure and covering seeds with the resulting ash to being stored in cloth bags or ceramic containers. The impact of these methods range considerably. Some methods, such as smoking the seeds over the cooking fire, proved ineffective, and germination rates were very low in seeds treated in this way. However, other methods, such as grinding up a local leaf into a powder and covering the seeds with the powder, were as effective as treating the seeds with commercial fungicides. Furthermore, these indigenous methods cost a fraction of the amount of commercially available methods' cost and are also much less expensive than buying seeds annually. The implication of this research is that it is important for researchers to test the efficacy of traditional seed saving methods as a way of establishing best practices and developing appropriate agricultural management practices that will help farmers alleviate poverty. Copyright © 2014 John Wiley & Sons, Ltd.

This paper presents a study of the relationship between phosphorus fractions and phosphorus release in the presence of manure. Dynamic changes in the characteristics of total phosphorus in surface water are simulated by waterlogged incubation. The study was carried out by comparing sterilized and non-sterilized treatments to analyze the effect of manure on the dynamics of phosphorus (P) release from soil. Experimental results show that manure application in paddy soil can significantly increase the content of phosphorus fractions (p