Cost Efficient Tillage and Rotation Options for Mitigating GHG Emissions from Agriculture in Eastern Canada

The economic efficiency of cropping options to mitigate GHG emissions with agriculture in Eastern Canada was analyzed. Data on yield response to tillage (moldboard plow and chisel plow) and six corn based rotations were obtained from a 20-year field experiment in Ontario. Budgets were constructed for each cropping system while GHG emissions were measured for soil carbon and were estimated for nitrous oxide according to IPCC methodology. Complex crop rotations with legumes, such as corn-corn-soybeans-wheat with red clover underseeded, have higher net returns and substantially (more than 1 Mg ha1 year1) lower GHG emissions than continuous corn. Reduced tillage reduces GHG emissions due to lower input use but no sequestration effect could be found in the soil from tillage. Rotation had a much bigger effect on the mitigation potential of GHG emissions than tillage. However, opportunity costs of more than $200 per Mg CO2 eq ha1 year1 indicate the limits to increase the mitigation potential beyond the level of the economic best cropping system.Environmental Economics and Policy,

COMPARATIVE ECONOMICS OF ALTERNATIVE AGRICULTURAL PRODUCTION SYSTEMS: A REVIEW

Farm Management,

A regulatory domain in the C-terminal extension of the yeast glycerol channel Fps1p

The Saccharomyces cerevisiae gene FPS1 encodes an aquaglyceroporin of the major intrinsic protein (MIP) family. The main function of Fps1p seems to be the efflux of glycerol in the adaptation of the yeast cell to lower external osmolarity. Fps1p is an atypical member of the family, because the protein is much larger (669 amino acids) than most MIPs due to long hydrophilic extensions in both termini. We have shown previously that a short domain in the N-terminal extension of the protein is required for restricting glycerol transport through the channel (Tamás, M. J., Karlgren, S., Bill, R. M., Hedfalk, K., Allegri, L., Ferreira, M., Thevelein, J. M., Rydström, J., Mullins, J. G. L., and Hohmann, S. (2003) J. Biol. Chem. 278, 6337-6345). Deletion of the N-terminal domain results in an unregulated channel, loss of glycerol, and osmosensitivity. In this work we have investigated the role of the Fps1p C terminus (139 amino acids). A set of eight truncations has been constructed and tested in vivo in a yeast fps1Δ strain. We have performed growth tests, membrane localization following cell fractionation, and glycerol accumulation measurements as well as an investigation of the osmotic stress response. Our results show that the C-terminal extension is also involved in restricting transport through Fps1p. We have identified a sequence of 12 amino acids, residues 535-546, close to the sixth transmembrane domain. This element seems to be important for controlling Fps1p function. Similar to the N-terminal domain, the C-terminal domain is amphiphilic and has a potential to dip into the membrane

Analysis of the pore of the unusual major intrinsic protein channel, yeast Fps1p

Fps1p is a glycerol efflux channel from Saccharomyces cerevisiae. In this atypical major intrinsic protein neither of the signature NPA motifs of the family, which are part of the pore, is preserved. To understand the functional consequences of this feature, we analyzed the pseudo-NPA motifs of Fps1p by site-directed mutagenesis and assayed the resultant mutant proteins in vivo. In addition, we took advantage of the fact that the closest bacterial homolog of Fps1p, Escherichia coli GlpF, can be functionally expressed in yeast, thus enabling the analysis in yeast cells of mutations that make this typical major intrinsic protein more similar to Fps1p. We observed that mutations made in Fps1p to "restore" the signature NPA motifs did not substantially affect channel function. In contrast, when GlpF was mutated to resemble Fps1p, all mutants had reduced activity compared with wild type. We rationalized these data by constructing models of one GlpF mutant and of the transmembrane core of Fps1p. Our model predicts that the pore of Fps1p is more flexible than that of GlpF. We discuss the fact that this may accommodate the divergent NPA motifs of Fps1p and that the different pore structures of Fps1p and GlpF may reflect the physiological roles of the two glycerol facilitators

Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity

Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity

Biomass for biofuel: Understanding the risks and opportunities for Ontario agriculture.

Markets for biomass are emerging across Canada however considerable concern has been expressed regarding the ability of Canada's arable land base to sustainably meet this emerging demand. Using Ontario as a case study, economic and environmental considerations that must be considered when designing biomass production systems based on either crop residues from maize (Zea mays L.), soybean (Glycine max (L.) Merr.), or winter wheat (Triticum aestivum L.), or on dedicated biomass crops, such as miscanthus (Miscanthus spp.) or switchgrass (Panicum virgatum) are reviewed. The Ontario agricultural land base is characterized by a growing prevalence of maize/soybean rotations, a high percentage of total arable land under the Canada Land Inventory categorized as Class 1 and 2, and geographically dispersed Class 3-5 land. Economic and environmental risks and opportunities of biomass production are demonstrated to be a function of the source of biomass, land availability, land classification, and existing land use patterns.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Miscanthus: a promising feedstock for lignocellulosic ethanol industry in Ontario, Canada

The life cycle of ethanol derived from miscanthus has been evaluated to determine its environment and economic viability. Net energy consumption, production cost and emission are estimated considering three scenarios (S1: all classes of land; S2: prime land; S3: marginal land, are used for miscanthus cultivation). Depending on the scenarios net energy consumption, production cost and emissions are found to be varied from 12.1 to 12.5 GJ m-3, 776.7 to 811.3$ m-3 and 0.7 to 1.3 t-CO2e m-3, respectively. Although energy consumption and production cost is slightly varied among the scenarios, the variation seems to be robust in the case of GHG emissions, where carbon dynamics play an important role. This study revealed that miscanthus is a promising feedstock for ethanol even if it is grown on marginal land which may abate competition with food crops and improve the farm economy in Ontario, Canada

An Approach to Identify the Suitable Plant Location for Miscanthus-Based Ethanol Industry: A Case Study in Ontario, Canada

The life cycle (LC) of ethanol extracted from Miscanthus has been evaluated to identify the potential location for the Miscanthus-based ethanol industry in Ontario, Canada to mitigate greenhouse gas (GHG) emissions and minimize the production cost of ethanol. Four scenarios are established considering the land classes, land use, and cropping patterns in Ontario, Canada. The net energy consumption, emissions, and cost of ethanol are observed to be dependent on the processing plant location and scenarios. The net energy consumption, emissions, and cost vary from 12.9 MJ/L to 13.4 MJ/L, 0.79 $/L to 0.84$/L, and 0.45 kg-CO2e/L to 1.32 kg-CO2e/L, respectively, which are reliant on the scenarios. Eastern Ontario has emerged as the best option. This study reveals that Miscanthus is a potential feedstock for the ethanol industries in Ontario, even if it is cultivated on marginal land. This study also highlights the contribution of energy crops (Miscanthus) to avoid the potential technical and economic constraints of lignocellulosic biomass for the renewable energy industry. Miscanthus may help avoid competition with food crops for prime land (higher quality land that is suitable for food crops), avoid the food versus fuel debate, help meet the ethanol demand, and achieve the GHG emissions abatement target of Canada

Cost Efficient Tillage and Rotation Options for Mitigating GHG Emissions from Agriculture in Eastern Canada

The economic efficiency of cropping options to mitigate GHG emissions with agriculture in Eastern Canada was analyzed. Data on yield response to tillage (moldboard plow and chisel plow) and six corn based rotations were obtained from a 20-year field experiment in Ontario. Budgets were constructed for each cropping system while GHG emissions were measured for soil carbon and were estimated for nitrous oxide according to IPCC methodology. Complex crop rotations with legumes, such as corn-corn-soybeans-wheat with red clover underseeded, have higher net returns and substantially (more than 1 Mg ha-1 year-1) lower GHG emissions than continuous corn. Reduced tillage reduces GHG emissions due to lower input use but no sequestration effect could be found in the soil from tillage. Rotation had a much bigger effect on the mitigation potential of GHG emissions than tillage. However, opportunity costs of more than $200 per Mg CO2 eq ha-1 year-1 indicate the limits to increase the mitigation potential beyond the level of the economic best cropping system