Tillage and field scale controls on greenhouse gas emissions

There is a lack of understanding of how associations among soil properties and management-induced changes control the variability of greenhouse gas (GHG) emissions from soil. We performed a laboratory investigation to quantify relationships between GHG emissions and soil indicators in an irrigated agricultural field under standard tillage (ST) and a field recently converted (2 yr) to no-tillage (NT). Soil cores (15-cm depth) were incubated at 25 degrees C at field moisture content and 75% water holding capacity. Principal component analysis (PCA) identified that most of the variation of the measured soil properties was related to differences in soil C and N and soil water conditions under ST, but soil texture and bulk density under NT. This trend became more apparent after irrigation. However, principal component regression (PCR) suggested that soil physical properties or total C and N were less important in controlling GHG emissions across tillage systems. The CO2 flux was more strongly determined by microbial biomass under ST and inorganic N content under NT than soil physical properties. Similarly, N2O and CH4 fluxes were predominantly controlled by NO3- content and labile C and N availability in both ST and NT soils at field moisture content, and NH4+ content after irrigation. Our study indicates that the field-scale variability of GHG emissions is controlled primarily by biochemical parameters rather than physical parameters. Differences in the availability and type of C and N sources for microbial activity as affected by tillage and irrigation develop different levels and combinations of field-scale controls on GHG emissions.     

Combustion features under different center of heat release of a diesel engine using dimethyl carbonate/diesel blend

Experiments were performed in a single cylinder common-rail diesel engine that adopts a low temperature premixed charge compression ignition (PCCI) mode. Combustion features of dimethyl carbonate (DMC)-diesel blends under various centers of heat release (COHRs) were revealed in details. With retarding of COHR, all the peaks of pressure and pressure rise rate and bulk gas temperature are postponed and declined in sequence. Normally, the crank angle of peak pressure is quite close to the COHR, while the peak of bulk gas temperature appears about 7°CA after COHR as a rule. The prolongation can be demonstrated at every stage of combustion such as q₁₀ and q₉₀ with the COHR being put backward. In addition, the heat release of diesel is completely slower than that of D10 fuel at various stages. Unfortunately, retarding of COHR implies a declining thermal efficiency of engines as well as a higher cyclic variation in general. Nevertheless, D10 blend has higher thermal efficiency than diesel thanks to high oxygen content of DMC and low boiling point that prompts better fuel atomization and complete combustion. Meanwhile, the cyclical variation of D10 is greater than diesel fuel owing to the low heat value, high latent heat of vaporization, and poor flammability of DMC. As a total, a comprehensive understanding of PCCI combustion features under different COHRs can be conducive to conducting effective management of combustion process and manipulating the subsequent emission performance to a favorable level.     

Comparison of jatropha and karanja biofuels on their combustion characteristics

Biofuel blends produced from Jatropha (Jatropha curcas) and Karanja (Pongamia pinnata) oil were evaluated for their combustion properties. Two kinds of blends (regular diesel with Jatropha and Karanja oil) were prepared at 20% volume to the diesel and tested as alternative fuels in single cylinder (vertical), water-cooled, direct injection diesel engine at the rated speed of 1500 rpm. The performance of the engine in terms of thermal efficiency at full load for diesel was 30%. For Jatropha and Karanja biodiesel blends, the thermal efficiencies were 29.0% and 28.6%, respectively. The maximum cylinder pressure and ignition delay for biodiesel fuel blends are very close to that of regular diesel. Prolonged combustion was observed for Karanja oil blend in comparison to Jatropha oil blend. The combustion pattern also reveals the slow burning characteristics of vegetable oils and this study indicates that the blended biofuels have combustion characteristics that are similar to regular diesel fuels.     

Effects of Coffee Management Intensity on Composition, Structure, and Regeneration Status of Ethiopian Moist Evergreen Afromontane Forests

The effect of arabica coffee management intensity on composition, structure, and regeneration of moist evergreen Afromontane forests was studied in three traditional coffee-management systems of southwest Ethiopia: semiplantation coffee, semiforest coffee, and forest coffee. Vegetation and environmental data were collected in 84 plots from forests varying in intensity of coffee management. After controlling for environmental variation (altitude, aspect, slope, soil nutrient availability, and soil depth), differences in woody species composition, forest structure, and regeneration potential among management systems were compared using one way analysis of variance. The study showed that intensification of forest coffee cultivation to maximize coffee production negatively affects diversity and structure of Ethiopian moist evergreen Afromontane forests. Intensification of coffee productivity starts with the conversion of forest coffee to semiforest coffee, which has significant negative effects on tree seedling abundance. Further intensification leads to the conversion of semiforest to semiplantation coffee, causing significant diversity losses and the collapse of forest structure (decrease of stem density, basal area, crown closure, crown cover, and dominant tree height). Our study underlines the need for shade certification schemes to include variables other than canopy cover and that the loss of species diversity in intensively managed coffee systems may jeopardize the sustainability of coffee production itself through the decrease of ecosystem resilience and disruption of ecosystem services related to coffee yield, such as pollination and pest control.     

铁合金电炉烟尘的性质与低温固结研究

本文研究了硅铁电炉布袋除尘收集的烟尘性能，烟尘低温固结球团的性能和工艺方法。研究结果表明，硅铁电炉烟尘中ＳｉＯ２ 约占９０ － ９５ ％ ，其它组分含量较低，有利于进行回收利用。烟尘密度小、粒度细、表面活性差、成球性能差。采用添加粘结剂进行自然养护和低温固结处理，均能获得强度较好的固结球团，能够加入铁合金炉回收利用。     

Reuse of de-inking sludge from wastepaper recycling in cement mortar products

This paper presents results of an investigation into the use of de-inking sludge from a paper recycling mill as feedstock material in the manufacture of cement mortar products, including masonry blocks and mortar renders. Both physical and mechanical properties of mortar specimens containing various amounts of de-inking sludge were investigated. It was observed that the addition of de-inking sludge to cement mortar at a fixed water-to-cement ratio significantly reduced flow properties and increased setting time. Water absorption and volume of permeable voids of cement mortar increased with increased dosage of de-inking sludge, with a corresponding reduction of bulk density. The 91-day compressive strength of mortar samples with 2.5 wt% and 20 wt% de-inking sludge loadings retained 83% and 62% respectively of the reference mortar strength. The corresponding drying shrinkage increased by up to 160% compared to reference samples. However, a de-inking sludge loading of up to 2.5 wt% did not significantly alter measured physical and mechanical properties. The results demonstrate that despite the high moisture absorbance of de-inking sludge due to its organic matter and residual cellulose fibre content, it serves as a potential supplementary additive and its cellulosic content proving to be an active set retardant to cementitious masonry products.     

Methane oxidation in an intensively cropped tropical rice field soil under long-term application of organic and mineral fertilizers

Methane (CH4) oxidation is the only known biological sink process for mitigating atmospheric and terrestrial emissions of CH4, a major greenhouse gas. Methane oxidation in an alluvial soil planted to rice (Oryza sativa L.) under long-term application of organic (compost with a C/N ratio of 21.71), and mineral fertilizers was measured in a field-cum-laboratory incubation study. Oxidation rates were quantified in terms of decrease in the concentration of CH4 in the headspace of incubation vessels and expressed as half-life (t(1)2) values. Methane oxidation rates significantly differed among the treatments and growth stages of the rice crop. Methane oxidation rates were high at the maximum tillering and maturity stages, whereas they were low at grain-filling stage. Methane oxidation was low (t(1)2) = 15.76 d) when provided with low concentration of CH4. On the contrary, high concentration of CH4 resulted in faster oxidation (t(1)2) = 6.67 d), suggesting the predominance of "low affinity oxidation" in rice fields. Methane oxidation was stimulated following the application of mineral fertilizers or compost implicating nutrient limitation as one of the factors affecting the process. Combined application of compost and mineral fertilizer, however, inhibited CH4 oxidation probably due to N immobilization by the added compost. The positive effect of mineral fertilizer on CH4 oxidation rate was evident only at high CH4 concentration (t(1)2 = 4.80 d), while at low CH4 concentration their was considerable suppression (t(1) = 17.60 d). Further research may reveal that long-term application of fertilizers, organic or inorganic, may not inhibit CH4 oxidation.     

Effect of organic amendment and plant roots on the solubility and mobilization of lead in soils at a shooting range

Lead (Pb) dissolving gradually from spent pellets constitutes a serious environmental risk in and near shooting ranges, and remediation measures are necessary to prevent its movement to deeper soil layers and ground water. In this study, the effectiveness of organic amendment and plant roots in stabilizing Pb was assessed in a microcosm experiment. Planted (Scots pine, Pinus sylvestris L.) and unplanted microcosms consisting of coarse-textured mineral soil covered with Pb-contaminated humic topsoil were coated with uncontaminated peat layers of 1 to 3 cm and incubated for 77 d. In a percolation test, the microcosms were washed with ultra pure water to simulate heavy rain so as to rinse water-soluble lead (Pbw) from the topsoil layer. Although Pbw remained below detection limits in the mineral soils in all test units, acid-soluble lead (Pba) increased. Peat amendment diminished Pba in the mineral soil layer, this effect being more pronounced in planted soils, indicating that Pb was taken up by the plants. The percolation test showed that the effect of Scots pine seedlings on Pb movement was minor when peat was added. A long-term dissolution test revealed that considerably more Pb was released from old pellets into soil extracts than from new ones, whereas only traces of Pb, if any, were dissolved in sterilized pure water.     

Biofuels: Efficiency,Ethics, and Limits to Human Appropriation of Ecosystem Services

Biofuels have lately been indicated as a promising source of cheap and sustainable energy. In this paper we argue that some important ethical and environmental issues have also to be addressed: (1) the conflict between biofuels production and global food security, particularly in developing countries, and (2) the limits of the Human Appropriation of ecosystem services and Net Primary Productivity. We warn that large scale conversion of crops, grasslands, natural and semi-natural ecosystem, (such as the conversion of grasslands to cellulosic ethanol production, or plantation of sugar cane and palm oil), may have detrimental social and ecological consequences. Social effects may concern: (1) food security, especially in developing countries, leading to an increase of the price of staple food, (2) transnational corporations and big landowners establishing larger and larger landholdings in conflict with indigenous areas and the subsistence of small farmers. Ecological effects may concern: (1) competition with grazing wild and domesticated animals (e.g., millions of grazing livestock in USA prairies), (2) an excessive appropriation of Net Primary Production from ecosystems, (3) threatening biodiversity preservation and soil fertility. We claim that is it well known how ecological and social issues are strictly interwoven and that large scale biofuels production, by putting high pressure on both fronts, may trigger dangerous feedbacks, also considering the critical fact that 9 billion people are expected to inhabit the planet by 2050. There is a need to conduct serious and deep analysis on the environmental and social impact of large scale biofuels production before important energy policies are launched at global level. Biofuels will not represent an energetic panacea and their role in the overall energy consumption will remain marginal in our present highly energivorous society, while their effect on food security and environment preservation may have detrimental results. We should also have the courage to face two key issues: (1) we cannot keep increasing resources consumption at present pace, and have to change our life style accordingly, and (2) we have to deal with population growth; we cannot expect to have 9–10 billions people inhabiting the earth by 2050, without this representing a major impact on its support system.     

Land Use Change on Coffee Farms in Southern Guatemala and its Environmental Consequences

Changes in commodity prices, such as the fall in coffee prices from 2000 to 2004, affect land use decisions on farms, and the environmental services they provide. A survey of 50 farms showed a 35 % loss in the area under coffee between 2000 and 2004 below 700 m with the majority of this area (64 %) being coffee agroforest systems that included native forest species. Loss of coffee only occurred on large and medium-scale farms; there was no change in area on cooperatives. Coffee productivity declined below 1,100 m altitude for sun and Inga shade coffee, but only below 700 m altitude for agroforest coffee. Coffee productivity was 37–53 % lower under agroforests than other systems. Increases in rubber and pasture were related to low altitude large-scale farms, and bananas and timber plantations to mid-altitude farms. Average aboveground carbon stocks for coffee agroforests of 39 t C ha^?1 was similar to rubber plantations, but one-third to one half that of natural forest and timber plantations, respectively. Coffee agroforests had the highest native tree diversity of the productive systems (7–12 species ha^?1) but lower than natural forest (31 species ha^?1). Conversion of coffee agroforest to other land uses always led to a reduction in the quality of habitat for native biodiversity, especially avian, but was concentrated among certain farm types. Sustaining coffee agroforests for biodiversity conservation would require targeted interventions such as direct payments or market incentives specifically for biodiversity.     

Retention of gases by hexadecyltrimethylammonium-montmorillonite clays

Intercalated montmorillonite clays with different amounts of organic hexadecyltrimethylammonium (HDTMA) cations were studied to analyse their CO, CH(4), and SO(2) gas retentions. Equilibrium adsorption was measured by using a standard volumetric apparatus at 25 degrees C and 0.1 MPa. The solids were characterised by X-ray diffraction. The levels of adsorption of SO(2) by organo-montmorillonites (0.3595-1.6403 mmol/g) were higher than those of CO (up to 0.0202 mmol/g) and CH(4) (up to 0.0273 mmol/g) gases. HDTMA montmorillonites may be effective adsorbents for removing SO(2) and for its potential separation in the presence of CO and/or CH(4) molecules, which can be present in contaminated air.     

Interrogating Social Sustainability in the Biofuels Sector in Latin America: Tensions Between Global Standards and Local Experiences in Mexico,Brazil, and Colombia

Across the Americas, biofuels production systems are diverse due to geographic conditions, historical patterns of land tenure, different land use patterns, government policy frameworks, and relations between the national state and civil society, all of which shape the role that biofuels play in individual nations. Although many national governments throughout the Americas continue to incentivize growth of the biofuels industry, one key challenge for biofuels sustainability has been concern about its social impacts. In this article, we discuss some of the key social issues and tensions related to the recent expansion of biofuels production in Mexico, Colombia, and Brazil. We argue that a process of “simplification” of ecological and cultural diversity has aided the expansion of the biofuels frontier in these countries, but is also undermining their viability. We consider the ability of governments and non-state actors in multi-stakeholder initiatives (MSI) to address social and environmental concerns that affect rural livelihoods as a result of biofuels expansion. We analyze the tensions between global sustainability standards, national level policies for biofuels development, and local level impacts and visions of sustainability. We find that both government and MSI efforts to address sustainability concerns have limited impact, and recommend greater incorporation of local needs and expertise to improve governance.     

A novel method to make regenerable core-shell calcium-based sorbents

A sorbent having a calcium oxide core and a clay shell was prepared and shown to be capable of reusable applications in absorption and desorption processes for carbon dioxide. The novelty of this sorbent is that only calcium carbonate and clay are used for its preparation with water as a binder. A two-step granulation procedure is used to get the core and then another step to coat the shell layer with the clay powder. A repeated wet-and-dry procedure probably makes the core porous yet strong enough to serve as a sorbent. The pellet is then calcined at 1200 degrees C for 2h to reach its final structure. The core-shell pellets have an overall diameter of 4.4mm with average shell thickness of 0.45 mm, crush load of 35 N and attrition index of 0.035 wt%/h. These results indicate that the pellets will probably be capable of withstanding the stress in future applications. Carbon dioxide absorption at or below 300 degrees C showed a maximum weight gain of 38% for our pellets. Finally, desorption in nitrogen at 800 degrees C can restore the pellet to its original state and hence it is ready for re-use as a sorbent.     

Effects of soil physical characteristics and biotic interferences on the herbaceous community composition and species diversity on the campus of Banaras Hindu University,India

Soil, water and species diversity relationships are central components of the vegetation ecology. In this connection, the present study was performed on the three sites within the campus of Banaras Hindu University of India, to relate herbaceous species diversity to soil physical characteristic and the intensity of biotic interferences. At each site, three, 10 m × 10 m plots were randomly established and within each plot, four quadrats each 50 cm × 50 cm were randomly placed for sampling. For each quadrat, number of individuals and their herbage cover were recorded by species. Soil physical characteristics (soil moisture, water-holding capacity, soil porosity and bulk density), elements of biotic interferences and α-diversity and its components were determined for each plot. The plots were ordinated by Non-metric Multidimensional Scaling (NMS) using Importance Value Indices of the component species. Results showed that the selected locations differed in terms of soil moisture and species diversity parameters due to differences in biotic interferences. NMS ordination yielded three groups corresponding to the three communities experiencing different intensity of land use. NMS axes were substantially related to the soil and herbaceous diversity parameters and suggested that the elements of soil physical characteristics, intensity of biotic interferences and regional herbaceous species pool had profound effect on the organization and determination of herbaceous floristic composition. Further, the sample locations exhibiting greater soil moisture, water-holding capacity, soil porosity and lesser soil bulk density harboured greater herbaceous diversity. A negative relationship between indices of species diversity and soil bulk density revealed that the dry and compact soils due to greater biotic pressure contributed to the loss of species diversity. Reduction in livestock numbers, grazing pressure and soil bulk density could be helpful in the promotion of soil quality and species diversity.     

Methane emissions of rice increased by elevated carbon dioxide and temperature

Methane (CH4) effluxes by paddy-culture rice (Oryza sativa L.) contribute about 16% of the total anthropogenic emissions. Since radiative forcing of CH4 at current atmospheric concentrations is 21 times greater on a per mole basis than that of carbon dioxide (CO2), it is imperative that the impact of global change on rice CH4 emissions be evaluated. Rice (cv. IR72) was planted in sunlit, closed-circulation, controlled-environment chambers in which CH4 efflux densities were measured daily. The CO2 concentration was maintained at either 330 or 660 micromol mol(-1). Air temperatures were controlled to daily maxima and minima of 32/23, 35/26, and 38/29 degrees C at each CO2 treatment. Emissions of CH4 each day were determined during a 4-h period after venting and resealing the chambers at 0800 h. Diurnal CH4 effluxes on 77, 98, and 119 d after planting (DAP) were obtained similarly at 4-h intervals. Emissions over four-plant hills and over flooded bare soil were measured at 53, 63, and 100 DAP. Emissions were negligible before 40 DAP. Thereafter, emissions were observed first in high-CO2, high-temperature treatments and reached a sustained maximum efflux density of about 7 mg m(-2) h(-1) (0.17 g m(-2) d(-1)) near the end of the growing season. Total seasonal CH4 emission was fourfold greater for high-CO2, high-temperature treatments than for the low-CO2, low-temperature treatment, probably due to more root sloughing or exudates, since about sixfold more acetate was found in the soil at 71 DAP. Both rising CO2 and increasing temperatures could lead to a positive feedback on global warming by increasing the emissions of CH4 from rice.     

Experimental investigations on direct injection diesel engines using grape seed oil methyl ester with different bowl geometries

In this paper, the performance of direct injection diesel engine was experimentally investigated under the influence of two different pistons’s geometry deep bowl combustion chamber (DBCC) and toroidal combustion chamber (TCC) compared with standard piston combustion chamber (SPCC) geometry. The experiments were carried out standard atmospheric conditions of 1.01325 bar and 30 ± 2 °C. The piston bowl was designed and developed without modifying the compression ratio of the engine. The investigations were carried out with B25 (25% GOME + 75% diesel), B50 (50% GOME + 50% diesel), B75 (75% GOME +25% diesel) and B100 (100% GOME) by volume blends for three different bowl geometries. The thermogravimetric analysis (TGA) was given the importance of higher in-cylinder temperature for the mass change of GOME leads to a more premixed phase of combustion. The results showed that DBCC has better combustion characteristics when compared with SPCC and TCC for all the blends. The B25 and B50 blends showed good combustion characteristics with DBCC and SPCC individually. While TCC showed average engine characteristics for all the blends categorically, the brake thermal efficiency for B25 blend confirmed a 4.7% higher than SPCC-diesel with DBCC piston, and the smoke, CO (Carbon monoxide), and HC (Hydrocarbon) are reduced by 9.2%, 30.7%, and 4.6%, respectively. Thus, the B25 blend in a DBCC piston engine was observed to be the distinction than other configurations. The results confirmed that the DBCC is a good option for B25 blend.     

Gaseous nitrogen and carbon losses from pig manure derived from different diets

Manipulation of the diets of pigs may alter the composition of the manure and thereby the environmental and agricultural qualities of the manure. Laboratory studies were performed to quantify the effect of manipulation of pig diets on the chemical composition of the derived manure (slurry), the potential emission of methane (CH4) and ammonia (NH3) during anaerobic storage of the manure, and the potential nitrous oxide (N2O) and carbon dioxide (CO2) emission after application of the manure to soil. The diets differed in contents of crude protein and salt (CaSO4), and the type and contents of nonstarch polysaccharides (NSP). Emissions of NH3 and CH4 during storage were smaller at a low than at a high dietary protein content. The emission of NH3 was significantly related to the contents of ammonium (NH4), total N, and pH. The emission of CH4 was significantly related to contents of dry matter, total C, and volatile fatty acids in the manure. The effect of manure composition on N2O emission markedly differed between the two tested soils, which points at interactions with soil properties such as the organic matter content. These types of interactions require soil-specific recommendations for mitigation of N2O emission from soil-applied pig manure by manipulation of the diet. From the tested diets, decreasing the protein content has the largest potential to simultaneously decrease NH3 and CH4 emissions during manure storage and N2O emission from soil. An integral assessment of the environmental and agricultural impact of handling and application of pig manure as a result of diet manipulation provides opportunities for farmers to maximize the value of manures as fertilizer and soil conditioner and to minimize N and C emissions to the environment.     

Assessment of biomass residue availability and bioenergy yields in Ghana

Biomass is an important renewable energy source that holds large potential as feedstock for the production of different energy carriers in a context of sustainable development, peak oil and climate change. In developing countries, biomass already supplies the bulk of energy services and future use is expected to increase with more efficient applications, such as the production of biogas and liquid biofuels for cooking, transportation and the generation of power. The aim of this study is to establish the amount of Ghana's energy demand that can be satisfied by using the country's crop residues, animal manure, logging residues and municipal waste. The study finds that the technical potential of bioenergy from these sources is 96 PJ in 2700 Mm³ of biogas or 52 PJ in 2300 ML of cellulosic ethanol. The biogas potential is sufficient to replace more than a quarter of Ghana's present woodfuel use. If instead converted to cellulosic ethanol, the estimated potential is seven times the estimated 336 ML of biofuels needed to achieve the projected 10% biofuels blends at the national level in 2020. Utilizing the calculated potentials involves a large challenge in terms of infrastructure requirements, quantified to hundreds of thousands of small-scale plants.     

Effects of a waste paper product on soil phosphorus, carbon, and bulk density

Applications of manures to agricultural fields have increased soil test values for P to high levels in parts of the USA and thus increased the likelihood that P will be transported to surface water and degrade its quality. Waste paper applications to soils with high STP (soil test P) may decrease the risk of P transport to surface water by decreasing DRP (dissolved reactive P) by the formation of insoluble Al-P complexes and providing organic matter to improve infiltration. A field experiment was conducted near Booneville, AR (USA) to assess the effects of different rates of a waste paper product addition on STP, soil bulk density, and total soil C with a soil with approximately 45 mg Bray1-P kg-1 soil (dry weight). A Leadvale silt loam soil (fine-silty, siliceous, thermic Typic Fragiudult) was amended with 0, 22, 44, or 88 Mg waste paper product ha-1 to supply approximately 90, 170, or 350 kg Al ha-1, respectively. One year after additions, there was a strong negative correlation between waste paper product application rates and soil bulk density, and a strong positive correlation between rates and total soil C content. Soil bulk density and total C 2 yr after additions, and soil DRP and Bray1-P were not affected by waste paper additions. These results support the hypothesis that decreases in DRP in runoff from soils receiving waste paper additions were probably due to changes in soil organic matter and bulk density, rather than changes in the chemical forms of soil P.     

Estimating bulk density in vertically exposed stoney alluvium using a modified excavation method

Despite many decades of education and refining land-use practices, accelerated stream bank erosion is still prevalent in the United States. Eroding stream banks produce a sediment load to the riverine system and can cause reduced water quality as a result of increased suspended sediment. As total maximum daily loads (TMDLs) for water bodies impaired by turbidity or suspended sediments become more numerous, a simple, in situ field technique will be needed to estimate the bulk density of readily erodible stream bank material so that reasonably accurate sediment loading rates can be estimated. In this study, the excavation/polyurethane-foam technique for estimating total bulk density was applied to vertically exposed alluvium with high coarse-fragment content. Though not previously attempted in vertically exposed alluvium with high coarse-fragment content, the excavation/polyurethane-foam technique appears to provide a reasonably accurate estimate of the total and soil (<2-mm size fraction) bulk density from vertically exposed, alluvial deposits with high coarse-fragment content (i.e., >70%) along eroding stream banks. Obtaining bulk density estimates using this method would facilitate calculation of sediment loading rates to riverine systems with actual field data.