Scientists look at preventing 'tipping points' in agriculture
Growing food, fuel and fiber entails the use of fertilizer and irrigation systems and results in land-use changes. These ‘side effects’ of agriculture can lead to regime shifts or ‘tipping points’ which include desertification, salinisation, water degradation, and changes in climate due to altered water flows from land to atmosphere. But paradoxically, these very ecosystem services also hold the keys to ecosystem restoration.
So say researchers who will participate in a symposium titled “Tipping points in the biosphere: Agriculture, water, and resilience” during the Ecological Society of America’s Annual Meeting. The theme of the meeting is “Ecology-based restoration in a changing world” and some 4,000 scientists are expected to attend.
As human populations shift to more meat-heavy diets, trade of agricultural products increases, and as demand for biofuels grows the pressure on some agricultural systems is mounting. The challenge is to figure out how to meet these demands while at the same time keep the ecosystem functions that underpin productivity working.
Tipping points occur when an ecosystem is overwhelmed by the demands placed on it and can no longer function the way it did before. In other words, it loses its resiliency which ultimately can lead to land that is rendered useless for growing crops.
Elena Bennett (McGill University), organizer of the symposium, says that we need to better understand large scale regime shifts in order to develop policies that sustain, rather than degrade, the very systems upon which humanity depends.
One of the reasons current agricultural landscapes are so prone to regime shifts is that prevailing management of them has tended to focus exclusively on improving one type of ecosystem service (e.g. food production, fiber production, biofuels production) at the cost of others, explains Bennett:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: agriculture :: sustainability :: ecosystem :: climate change ::
She notes that agriculture is now one of the main driving forces of global environmental change. Bennett and other presenters in this session have identified potential tipping points related to water and agriculture that could have major global consequences.
No human activity has so large an impact on water systems as does agriculture, according to Johan Rockstrom (Stockholm Environment Institute, Sweden). He notes that the future will bring an even greater demand on fresh water for food production — by 2050 global water use for food production alone will need to double.
Line Gordon (Stockholm University, Sweden) will examine the redistribution of vapor flows brought about by irrigation. Gordon notes that the pattern of change varies and identifies the mid-United States, the Amazon, the Sahel, India, and Northern China as the most likely areas to undergo climate change, driven by these altered continental vapor flows.
Ellen Marie Douglas (University of Massachusetts) will focus on potential impacts on India’s Monsoon Belt, home to a large part of the globe’s population. India has the largest irrigated agricultural area in the world, with more than 90 percent of the country’s water supporting irrigated agriculture. Vapor fluxes in India’s wet season are up by 7 percent and are up 55 percent in the dry season. Douglas and her colleagues attribute two-thirds of this change to irrigated agriculture.
Drawing from research examples in the Mississippi River, Simon Donner (Princeton University), will discuss the role of nitrogen fertilizer in the health of downstream ecosystems, in particular their potential sensitivity to climate change.
Navin Ramankutty (McGill University) likens land use changes to fuel emissions in their potential to drive climatic changes. According to Ramankutty, local land cover changes may very likely generate changes elsewhere by altering the general circulation of the atmosphere. He points to Canada, Eastern Europe, the former Soviet Union, Mexico, and Central America as places where land clearing for cultivation may have inadvertently decreased suitability for growing crops.
Brandon Bestelmeyer (USDA-ARS Jornada Experimental Range) will examine tipping points in rangelands and will explore various socio-economic factors contributing to rangeland degradation.
Others presenting at the session are Garry Peterson (McGill University), Lance Gunderson (Emory University), and Max Rietkerk (Utrecht University, The Netherlands).
“Our hope is that if we can identify potential regime shifts, we can alter our management to avoid them,” says session organizer Bennett.
Picture: 'terra preta' or 'dark earth' soils offer an example of an agricultural system that withstands the test of time. The technique is based on sequestring biochar (agrichar) in soils to make them more fertile, to improve their water retention capacities and to boost agricultural output in a genuinely sustainable way. Left: a nutrient poor oxisol, right: a biochar-enriched, fertile oxisol. These soils are now being looked at in the context of carbon-negative biofuels, which could help restore degraded soils. Courtesy: Bruno Glaser.
References:
Eurekalert: Tipping points - August 6, 2007.
Article continues
So say researchers who will participate in a symposium titled “Tipping points in the biosphere: Agriculture, water, and resilience” during the Ecological Society of America’s Annual Meeting. The theme of the meeting is “Ecology-based restoration in a changing world” and some 4,000 scientists are expected to attend.
As human populations shift to more meat-heavy diets, trade of agricultural products increases, and as demand for biofuels grows the pressure on some agricultural systems is mounting. The challenge is to figure out how to meet these demands while at the same time keep the ecosystem functions that underpin productivity working.
Tipping points occur when an ecosystem is overwhelmed by the demands placed on it and can no longer function the way it did before. In other words, it loses its resiliency which ultimately can lead to land that is rendered useless for growing crops.
Elena Bennett (McGill University), organizer of the symposium, says that we need to better understand large scale regime shifts in order to develop policies that sustain, rather than degrade, the very systems upon which humanity depends.
One of the reasons current agricultural landscapes are so prone to regime shifts is that prevailing management of them has tended to focus exclusively on improving one type of ecosystem service (e.g. food production, fiber production, biofuels production) at the cost of others, explains Bennett:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: agriculture :: sustainability :: ecosystem :: climate change ::
She notes that agriculture is now one of the main driving forces of global environmental change. Bennett and other presenters in this session have identified potential tipping points related to water and agriculture that could have major global consequences.
No human activity has so large an impact on water systems as does agriculture, according to Johan Rockstrom (Stockholm Environment Institute, Sweden). He notes that the future will bring an even greater demand on fresh water for food production — by 2050 global water use for food production alone will need to double.
Line Gordon (Stockholm University, Sweden) will examine the redistribution of vapor flows brought about by irrigation. Gordon notes that the pattern of change varies and identifies the mid-United States, the Amazon, the Sahel, India, and Northern China as the most likely areas to undergo climate change, driven by these altered continental vapor flows.
Ellen Marie Douglas (University of Massachusetts) will focus on potential impacts on India’s Monsoon Belt, home to a large part of the globe’s population. India has the largest irrigated agricultural area in the world, with more than 90 percent of the country’s water supporting irrigated agriculture. Vapor fluxes in India’s wet season are up by 7 percent and are up 55 percent in the dry season. Douglas and her colleagues attribute two-thirds of this change to irrigated agriculture.
Drawing from research examples in the Mississippi River, Simon Donner (Princeton University), will discuss the role of nitrogen fertilizer in the health of downstream ecosystems, in particular their potential sensitivity to climate change.
Navin Ramankutty (McGill University) likens land use changes to fuel emissions in their potential to drive climatic changes. According to Ramankutty, local land cover changes may very likely generate changes elsewhere by altering the general circulation of the atmosphere. He points to Canada, Eastern Europe, the former Soviet Union, Mexico, and Central America as places where land clearing for cultivation may have inadvertently decreased suitability for growing crops.
Brandon Bestelmeyer (USDA-ARS Jornada Experimental Range) will examine tipping points in rangelands and will explore various socio-economic factors contributing to rangeland degradation.
Others presenting at the session are Garry Peterson (McGill University), Lance Gunderson (Emory University), and Max Rietkerk (Utrecht University, The Netherlands).
“Our hope is that if we can identify potential regime shifts, we can alter our management to avoid them,” says session organizer Bennett.
Picture: 'terra preta' or 'dark earth' soils offer an example of an agricultural system that withstands the test of time. The technique is based on sequestring biochar (agrichar) in soils to make them more fertile, to improve their water retention capacities and to boost agricultural output in a genuinely sustainable way. Left: a nutrient poor oxisol, right: a biochar-enriched, fertile oxisol. These soils are now being looked at in the context of carbon-negative biofuels, which could help restore degraded soils. Courtesy: Bruno Glaser.
References:
Eurekalert: Tipping points - August 6, 2007.
Article continues
Monday, August 06, 2007
Scientists develop more efficient biorefining process to make ethanol from wheat
As oil prices soar, demand for bioethanol to stretch out supplies of gasoline has increased dramatically, along with frenzied research efforts to find the best raw materials and conversion processes for its economical production.
Cereals and sugar crops are currently the preferred raw materials for bioethanol production due to availability and low processing cost. In the EU, wheat is more widely cultivated and could be regarded as the preferred cereal grain for bioethanol production. The predominant process for wheat conversion into a fermentation feedstock begins with a simple dry milling stage leading to the production of whole wheat flour. The starch content in whole wheat flour is then hydrolyzed into glucose by commercial enzymes. The resulting glucose solution is fermented into ethanol after the addition of nutrient supplements. This process finally leads to the production of only one coproduct (Dried Distiller's Grain), which has a low market value as animal feed.
In the new study, Apostolis Koutinas and colleagues describe a simplified biorefining method that uses fewer steps and less energy and generates fewer waste products but more valuable byproducts (schematic, click to enlarge). The economics and efficiency of bioethanol production from wheat could thus be improved by fractionating the grain into the fermentable fraction and several nonfermentable fractions, including bran, germ and protein, that have a wide spectrum of end-uses.
The main differences between the proposed and the traditional dry milling of wheat are:
- Wheat components that are not fermentable during Saccharomyces cerevisiae cultivations for bioethanol production are separated prior to fermentation. In this way, two coproducts are produced (bran-rich pearling and gluten) with current and potential market outlets that could improve process economics. In addition, the removal of non-fermentable solids from yeast fermentation leads to the production of pure yeast cells that have a much higher market value and diversified market outlets as compared to Dry Distillers Grains (with solubles) produced by traditional wheat dry milling.
- Hydrolysis of starch or any remaining protein and phytic acid is achieved by consortia of enzymes that are produced by Aspergillus awamori fermentation on wheat flour. Simultaneous gelatinization, liquefaction, and saccharification is achieved at temperatures less than 70 C because the crude filtrate used from fungal fermentations contains all of the enzymes required to hydrolyze wheat components. Fungal cells were grown on exactly the same medium to produce enzymes that led to complete hydrolysis of wheat starch and protein during fermentation. Depending on plant capacity, this processing scheme leads to lower energy requirements and capital investment as compared to traditional processing that uses separate liquefaction and saccharification stages.
- Wheat is the sole raw material used throughout this process. A minimum amount of waste is produced by regenerating nutrients consumed during A. awamori fermentation via fungal autolysis. Fungal autolysates are used to supply additional nutrients for yeast fermentation.
In the process presented by the scientists, starch hydrolysis and fungal autolysis are carried out in separate reactions. However, the operating conditions employed for starch hydrolysis (60 C and uncontrolled pH) and fungal autolysis (55 C and uncontrolled pH) are very similar. This creates the opportunity to integrate these two unit operations in a single batch unit operation leading to lower capital investment and processing costs:energy :: sustainability :: wheat :: biofuels :: ethanol :: efficiency :: by-products :: biorefining :: bioconversion ::
The study then presents experimental results that justify the feasibility of integrating starch hydrolysis and fungal autolysis in the same unit operation for the production of a nutrient-complete medium for bioethanol production.
The feedstock production process including continuous operation for fungal fermentation and combined hydrolytic/autolytic reaction has been cost-optimized by the scientists by nonlinear programming. A continuous scheme for starch hydrolysis is proposed where initial gelatinization and liquefaction is carried out at significantly lower temperature (68 C) and faster reaction rate (up to 10 min residence time) as compared to the conventional process due to the utilization of the enzyme consortium produced from fungal fermentation. Subsequently, starch saccharification is carried out together with fungal autolysis at 55 C in the same unit operation.
Depending on the selected combination of physical and biological treatment, the optimized process yields various fractions enriched in bran, wheat germ and proteins that could be sold or utilized for the extraction or production of value-added products, boosting income of biorefineries, the scientists say.
This process could substitute for the conventional wheat dry milling process that is currently employed in industry. The most important unit operations of the proposed continuous scheme are a fungal fermentation producing enzymes and fungal cells and a combined hydrolytic/autolytic reaction producing a nutrient-complete medium.
References:
Najmul Arifeen, Ruohang Wang, Ioannis Kookos, Colin Webb, and Apostolis A. Koutinas, "Optimization and Cost Estimation of novel Wheat Biorefining for Continuous Production of Fermentation Feedstock", Biotechnol. Prog., 23 (4), 872 -880, 2007. DOI: 10.1021/bp0700408 S8756-7938(07)00040-9
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posted by Biopact team at 6:55 PM 0 comments links to this post