Scientists find link between carbon dioxide and evolution of C4 grasses

How a changing climate can affect ecosystems is an important and timely question, especially considering the recent global rise in greenhouse gases. Now, in an article published online on December 20th in the journal Current Biology, a team of European and American evolutionary biologists provide strong evidence that changes in global carbon dioxide levels probably had an important influence on the emergence of a specific group of highly efficient plants, termed C4 grasses, which includes major cereal crops, plants used for biofuels (sugarcane, sorghum), and species that represent important components of grasslands across the world.

C4 photosynthesis in grasses is one of the most successful ecological and evolutionary innovations in plant history, the scientists write. The C4 pathway is a fuel injection system for photosynthesis that increases the rate of leaf sugar production in hot climates. Most plants on Earth use the C3 photosynthetic pathway, which fixes carbon dioxide (CO2) from the atmosphere using the enzyme Rubisco. The C3 cycle uses this fixed CO2 and energy from sunlight to manufacture sugars. The process is inefficient because Rubisco is not saturated and not very specific, which means that it also fixes atmospheric oxygen. This inefficiency increases at high temperatures and low CO2 concentrations.

C4 plants overcome the inefficiency of C3 photosynthesis using a combination of anatomical and physiological tricks. First, the C3 cycle is isolated from the atmosphere within a leaf compartment. Secondly, the C4 cycle pumps CO2 into this compartment, filling it with CO2 and ensuring that Rubisco fixes nothing else. The 'pump' is powered by energy from sunlight, and works by using the enzyme PEPc to fix carbon in the form of bicarbonate (HCO3).

C4 plants are especially equipped to combat the energetically costly process known as photorespiration, that can occur under conditions of high temperature, drought, high salinity, and — with relevance to these latest findings — low carbon dioxide levels.

Although a combination of any of these factors might have provided the impetus behind the evolution of the various C4 lineages, it had been widely speculated that a drop in global carbon dioxide levels, occurring approximately 30 million years ago during the Oligocene period, may have been the major driving force. Establishing the link between the two, however, has proven difficult partly because there are no known fossils of C4 plants from this period.

Enter Pascal-Antoine Christin and colleagues from the University of Lausanne, Switzerland, who decided to take an alternative approach to date a large group of grasses. By using a 'molecular clock' technique, the authors were able to determine that the Chloridoideae subfamily of grasses emerged approximately 30 million years ago, right around the time global carbon dioxide levels were dropping. Furthermore, a model of the evolution of these grasses suggests that this correlation is not a trivial coincidence and instead reflects a causal relationship:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: sugarcane :: sorghum :: photosynthesis :: C4 :: efficiency :: climate change :: carbon dioxide ::

As the authors noted in their study, many of the C4 grasses evolved after the drop in global carbon dioxide levels 30 million years ago. How to explain this? The authors speculate that while an atmosphere low in carbon dioxide established the basic conditions necessary for C4 evolution, other ecological factors might be at work.

In light of this, the authors hope to apply the same approaches used in the paper described here to investigate the role of other variables, such as drought, salinity, and flooding, in the evolution of C4 plants.

In addition to improving our understanding of how climate changes influenced ecosystems in the past, such studies may allow predictions of how human activities could affect the planet in the future.

Indeed, with regard to global carbon dioxide levels, Christin and colleagues write, “besides its influence on climatic variables, increased CO2 concentration could trigger important ecological changes in major terrestrial ecosystems by affecting the distribution of C4-dominated biomes and the affiliated flora and fauna.”

This implies that a reversal of the conditions that favored C4 plants could potentially lead to their demise — a startling prospect if one considers the human race’s reliance on C4 crops like corn, sugarcane, sorghum, and millets.

The researchers include Pascal-Antoine Christin, Guillaume Besnard, Emanuela Samaritani, and Nicolas Salamin, all of the Department of Ecology and Evolution, Biophore, University of Lausanne, Switzerland; Melvin R. Duvall, Department of Biological Sciences, Northern Illinois University, DeKalb, Ill., USA; Trevor R. Hodkinson, Department of Botany, School of Natural Sciences, University of Dublin, Trinity College, Dublin, Ireland, and Vincent Savolainen, Imperial College, Berkshire, UK.

References:
Pascal-Antoine Christin, et al, "Oligocene CO2 Decline Promoted C4 Photosynthesis in Grasses", Current Biology, published online before print, December 20, 2007, DOI: 10.1016/j.cub.2007.11.058

Eurekalert: A link between greenhouse gases and the evolution of C4 grasses - December 20, 2007.

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Canadian researchers study co-firing of peat and biomass with coal

Peat Resources Limited announces it will collaborate with the Ontario Centre for Excellence for Energy (OCE), Lakehead University and other partners on two research programs to examine peat fuel harvesting and processing systems. Funding for the program is managed by OCE under the auspices of the provincially-financed Atikokan Bioenergy Research Centre. OCE has allocated $720,000 over two years to a project aimed at sustainably harvesting the resource, while $880,000 has been granted for research on co-firing peat and biomass with coal, to lower the carbon emissions from power generation.

The first project, 'Environmental Effects of Wet Harvesting Peat as an Alternative Energy Source for the Atikokan Generating Station', will be led by scientists at Lakehead University (Thunder Bay) in conjunction with peatland experts from McMaster University (Hamilton). Peat Resources Limited is contributing to the project through provision of its unique knowledge and experience in peat fuel development and by providing access to peatlands in its licensed areas near Upsala (northwest Ontario) for demonstration and monitoring of restoration models. Results of related activities by the Company on its licensed peatland areas in western Newfoundland will also be contributed to the project.

In a second project partners will analyse the co-firing of peat and biomass with coal for power generation. This research is also being led by Lakehead University in partnership with CANMET Energy Technology Centre (Ottawa) and Ontario Power Generation. Peat Resources Limited will be supplying processed peat fuel pellets from its small-scale production facility in Stephenville (Newfoundland), firstly for pilot scale trials at CANMET and later, in 2008, for a large 500 tonne combustion trial by Ontario Power Generation at the Atikokan Generating Station.

Peat is found in deposits mainly in the earth’s north temperate latitudes. It is partially carbonized organic matter, originating from the decomposition of vegetation in bogs, marshes or heathland under waterlogged (anaerobic) conditions. Peat is an early stage of the development of coal and in the dried state is comprised of approximately 60% carbon:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: peat :: co-firing :: emissions :: Ontario :: Canada ::

Peat bogs develop over 10 to 12 thousand years, about 1 to 2 millimeters a year. A bog depends on rainfall to support its waterlogged condition. Generally the water table is very stable remaining within a few centimeters of the bog’s surface. The bogs contain both decomposed (fuel) and surficial (horticultural) peat, which is less humified and typically found in the top layers of the bog. Peat has two main applications: general soil improvement/growing medium (horticultural and agricultural) and increasingly as a fuel source for power generation.

World’s Peat Deposits
Peat has been used as a fuel for thousands of years, particularly in Northern Europe. Peat resources throughout the world are enormous. In Finland, Sweden, Ireland and Russia peat is a significant source of electrical energy. Operations in these countries have mastered the harvest of peat bogs and the use of peat as a fuel for electrical power generation. In Canada and the United States, peat has been used most commonly as a soil conditioner in horticulture. Canada’s peat resources in Ontario have been mapped and tested. Their development for power generation is overdue given the need for clean power at a reduced environmental impact.

Ontario’s Peat Deposits
Canada has the world’s largest peat fuel resources estimated to be 41% of the world’s total of 43 billion tonnes, equivalent to 29 billion tonnes of coal.

A large proportion of these resources is found in Ontario (map, click to enlarge). Reserves are equivalent to 14 billion tonnes of coal, sufficient to satisfy its use for energy for centuries. Peat fuel development will reduce dependence upon out-of-province energy supplies, and will help Ontario achieve energy self-sufficiency.

There would be an opportunity, through local initiatives, for northern communities to play a dynamic long term role in Ontario’s peat fuel future. Peat utilization and associated development with participation by private industries could spur economic revival across Northern Ontario.

Peat Fuel Characteristics
Basic requirements for peat fuel are high calorific value, low ash content, low levels of sulphur and mercury, and high bulk density. Raw peat in Ontario which has undergone sufficient in-situ decomposition, meets these requirements.

To use raw peat as a fuel, dewatering is essential. In various parts of the world, bulk peat is burned at 50% moisture content, achieved by air drying raw peat, with or without mechanical dewatering. At this moisture content, its calorific value typically will range from 4,000 - 5,500 BTU/lb, similar to lignite.

Company sampling indicates the probable average will be approximately 9,600 BTU/lb in the dry state within the area of interest.

For peat fuel to compete with higher calorific fuels, it must be dewatered to about 10% moisture content. At that level, its calorific value will increase to between 7,200 - 10,000 BTU/lb, with the higher range levels from pre-selected bogs.


Both new research projects will provide important scientific and technical data supporting the application of peat fuel as an economic and environmentally attractive alternative to fossil fuels, such as coal, for power generation in Ontario and other North American jurisdictions.

Peat Resources Limited was formed to explore, develop and produce peat fuel for use in electricity generating stations and other facilities that require a long-term assured supply of economically competitive, environmentally favourable, and consistent quality fuel. With a strong resource base in Ontario and Newfoundland, an expert management team and unique knowledge of peat processing technology, the company is positioned to be the pre-eminent leader in this new North American energy industry.

References:
Peat Resources: Peat Resources Limited signs research collaboration agreement - December 12, 2007.

Ontario Center for Excellence for Energy.

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Boeing imagines future network of decentralised biofuel producers

Increasing air traffic is the ultimate symbol of the world's rapid globalisation. Large jets take thousands of people to the other side of the planet in a matter of hours, fill up their tanks at the airport and carry on to their next destination. Non-stop. One factor that has made this revolution possible is the availability of inexpensive, standardized jet-fuel, made from petroleum. The fuel is the same in Singapore and Boston, in Rio de Janeiro and in Brussels.

However, if it is up to Boeing, this will soon change. The aiframer imagines a world in which there are thousands of independent biofuel producers each making their own fuel from the most efficient local feedstocks and to a common global standard. Boeing's biofuel strategy has greatly expanded and is moving in this direction as the company prepares to select a specific biofuel source for two demonstration flights scheduled next year.

A series of laboratory tests completed by Boeing in the third quarter of this year confirmed that biofuels for large aircraft can be practically derived from far more feedstocks than previously believed, says Bill Glover, Boeing's director of environmental strategy. Glover wrote the report titled 'Alternate Fuels for use in Commercial Aircraft' [*.pdf] in which different biofuel production pathways for aviation fuels are explored. Boeing's lab tests showed that a variety of feedstocks can produce biofuels with kerosene-like freezing characteristics. Boeing also now believes a number of such biofuels can be affordably mass-produced for the aviation industry.

Distributed network
These findings have widened Boeing's vision for the future use of biofuel by airlines. Instead of a single, huge repository of biofuel feedstock to supply the world's airlines, Boeing envisions the growth of a distributed network with multiple feedstocks harvested for biofuel around the world, says Glover. The shift in strategy may have serious implications for the future of the energy industry. Glover likens the change to the way personal computers overtook mainframes about 20 years ago:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: distributed :: decentralisation :: aviation :: jet fuel ::

Industrial energy production may shift from monolithic producers of petroleum to a distributed network of biofuel providers, each cultivating the feedstock most appropriate for its geography and climate, he says. Each biofuel type will be produced to meet the industry's current fuel standard, he adds. So an airliner fuelled by one feedstock type can be refuelled by another biofuel source.

Boeing believes its role will be to serve as a catalyst for a distributed biofuel production system that it sees emerging within the next five years. Unlike an airline, Boeing does not buy fuel in bulk, but it may be able to provide other means of financing and technical support.

The first step is to prove the feasibility of biofuel-powered commercial aircraft. Boeing has teamed with Virgin Atlantic to test a General Electric-powered 747 (more here) and with Air New Zealand to test a Rolls-Royce-powered 747 (earlier post).

The flight-test programme is likely to consist of a single flight and consume a total of about 3,800 litres (1,000 gallons) of biofuel, says Glover. The company is close to selecting a feedstock for the flight-test programme, but Glover emphasises that this biofuel type is for demonstration purposes only.


Research into bio-jet fuels has exploded over the past years, partly because airlines' profitability strongly depends on fuel costs and because bio-jet fuels promise to reduce emissions considerably. But biofuels for aviation present several challenges: they require high-performance characteristics, in particular the capacity to remain fluid at low temperatures and the need for smooth blending with petroleum based fuels. Gradually, biofuels are being designed that approach the required cold tolerance threshold.

Likely candidates are synthetic biofuels, obtained from gasifying biomass that is liquefied by Fischer-Tropsch synthesis ('biomass-to-liquids'). Such fuels can be refined into designer fuels with specific characteristics. Another potential fuel is 'green diesel' based on a hydrogenation process of vegetable oils.

Some recent initiatives in bio-jet fuel research include a large program by the French aerospace industry into second-generation (synthetic) biofuels and other candidates. The project, known as CALIN is being initiated by a conglomerate of research organisations consisting of France's aerospace research agency ONERA, propulsion company Snecma and members of the country's Aerospace Valley group which unites most of Europe's leading aerospace manufacturers, including EADS, Airbus, Air France Industries, Alstom and Dassault (earlier post).

Snecma recently succeeded in testing a CFM56-7B jet engine with an ester-based biofuel at a Snecma site in Villaroche. The engine is produced by a joint venture between Snecma, CFM International, and General Electric Company. The fuel used was a methylester derived from plant oil, mixed with 70% Jet-A1 kerosene. The successful test with the unmodified engine reduced carbon dioxide emissions by 20% (earlier post and here).

A large number of private initiatives are underway to develop biokerosene. Amongst them Diversified Energy which developed biofuels that withstand very cold temperatures and can be used in aviation. Their process consists of freeing up the free fatty acids contained in triglycerides from glycerol and passing them through a catalyst after which a resulting gas is synthesized into a liquid (earlier post)

UOP, a Honeywell company, has accelerated research and development on renewable energy technology to convert vegetable oils to military jet fuels. UOP developed a technique based on hydroprocessing that may yield fuels that meet the stringent requirements (more here).

The University of North Dakota recently received a US$5 million grant to develop military bio-jet fuels (earlier post). Whereas North Carolina State University found an innovative technology for the production of biofuels for jet aircraft based on transforming glycerol, the major byproduct of biodiesel (earlier post).

Obviously, several armies are looking into biofuels for aviation as well. A study for the US Military, written by Sasol, concluded that synthetic biofuels (Fischer-Tropsch) can power the entire military - including its airforce - in case of severe oil supply disruptions (earlier post). Finally, the U.S. Air Force has been experimenting extensively with synthetic fuels, which can be made from biomass. It already ground-tested them in real engines (earlier post).

Brazil's state-owned Petrobras announced it plans to introduce a type of bio-jet fuel named 'Bio QAV' in 120 of the country's airports, with concrete trials to begin in 2008. 'Bio QAV' ('Biokerosene for Aviation') is based on the H-bio second-generation biodiesel production process, which relies on hydrotreating vegetable oils (more here).

And most recently, the US Airforce made the first ever transcontinental flight of a C-17 on synthetic fuels, which can be made from biomass (previous post).

References:
FlightGlobal: Boeing expands biofuel strategy - December 20, 2007.

David L. Daggett, Robert C. Hendricks, Rainer Walther, Edwin Corporan, "Alternate Fuels for use in Commercial Aircraft" [*.pdf], Boeing, 2007.

Biopact: Virgin Atlantic to test biofuel in 747 in early 2008 - October 16, 2007

Biopact: Boeing, Air New Zealand and Rolls-Royce to conduct biofuel flight demonstration - September 28, 2007

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North Carolina State University develops experimental biomass harvester

Forestry engineers from North Carolina State University (NCSU) are developing an experimental biomass harvester that sucks up and pulverizes woody undergrowth and trunks from forest floors. The biomass can then be used for the production of cellulosic biofuels or as a feedstock for biomass power plants. Several similar machines are under development elsewhere, with a first one in Finland already being commercialised; it provides wood chips on the spot, for the emerging forest-based bioenergy sector (previous post).

A prototype of the new machine being developed by NCSU had its first public demonstration in woods east of New Bern, North Carolina, where it gobbled trees in the forest off County Line Road. The event was attended by the gamut of public and private forest-related industries and service in the state.

The harvester works as follows:

• the 56,000-pound machine is pushed by a tractor on treads; it boasts a 440-horsepower engine, making it a quite powerful tool
• despite its weight, the machine produces ground pressure of only 7.1 pounds per square foot, so it moves easily over soft forest bed and pocosin.
  
• the harvester cuts a trail after which its carbide teeth pulverize everything in its six-foot path
• a belt-driven vacuum sucks the ground-up cuttings through an extended chute over the cab and into an agricultural silage wagon hitched to the tractor
• the pulverised biomass is then ready to be utilized as an energy source
• the machine can now harvest between two and four tons of forest bulk an hour
  
• to break even when the biomass is sold as a low-cost feedstock for electricity production at a biomass plant, it would have to double its current output; cellulosic biofuels offer a more promising market
  

The experimental biomass harvester may be four or five years away from profitable use but offers real promise for renewable energy, said Joseph Roise, professor of forestry and operations research at NCSU’s College of Natural Resources:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: cellulose :: harvesting equipment :: efficiency :: forestry :: fire prevention ::

The machine is being developed by NCSU engineers in cooperation with Tim Tabak, a forestry management consultant, for Fecon Inc., manufacturer of the heavy equipment and attachments including Bull Hog commercial mulchers.

The new harvester allows more of the forest’s organic products — bushes, leaves and needles, and trees under 6 inches in diameter — to be used for biomass based biofuels such as Fischer-Tropsch diesel and cellulosic ethanol in addition to its present market in steam-generated electric production, Roise said. When perfected, it is expected to be used mostly for plantation thinning in tree farming, for clearing between the rows, and for forest management, he added.

Roise has been working since the summer with Tabak and NCSU Forestry graduate students Lindsay Hannum and Glen Catts to correct design flaws. Tabak said, that they have to sharpen the teeth during clearing, and that changing the teeth is a challenge. Without air wrenches it took up to 2 hours.

But Roise said the work thus far has produced results much better than they ever thought. A representative for Fecor, Bill Causey of Pittsboro, said the machine offers 'an exciting deal' if you can get it to work. The machine can now harvest between two and four tons of forest bulk an hour. But it needs to be able to harvest about 10 tons an hour to break even on the money it can make selling the harvest for fuel to Craven Wood Energy for steam-generated electricity.

Croatan National Forest District Ranger Lauren Hillman sees potential for forest management in fire prevention and habitat preservation or restoration. Camp Lejeune’s efforts to restore habitat for red-cockaded woodpeckers might be able helped by the machine, said Danny Marshburn, base forest manager. John Duff of Rankin Timber Company in New Bern said, it will be a useful tool on a lot of forest land that is tough to manage.

Its real profitability, however, lies in harvesting brush for next generation biofuels. Its advantage for that use is that it blows underbrush upward without picking up the dirt. The product saved from just being mulch on the forest floor contains the necessary chemical compounds for the manufacture of liquid fuels, Roise and fellow NCSU professor Dennis Hazel said. The professors are already debating which element of the biomass grabbed by the harvester will make it pay off first.

Picture: NCSU Forestry professor Joseph Roise is dwarfed by the 56,000-pound biomass harvester. Credit: Sue Book/Sun Journal.

References:
Sun Journal: Prototype biomass harvester devours small trees, underbrush - December 19, 2007.

Biopact: Efficient timber harvester delivers wood chips on the spot, improves biomass logistics - August 19, 2007

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ISU survey: Iowa farmland prices keep breaking records on biofuels

The Iowa State University Extension's annual survey on land prices shows that because of a surging demand for corn and soybeans for a rapidly expanding biofuels industry farmland prices in Iowa keep breaking records. The average value of an acre of farmland in Iowa - the heart of America's 'Grain Belt' - increased by just over $700 during the past year, to an all-time high of $3,908 ($9,656 per hectare). The trend confirmed that of last year's survey, when cropland in Iowa rose to a record US$3,204 per acre (US$7917 per hectare) (previous post).

The land boom is being driven by the developing biofuel economy, according to Mike Duffy, ISU Extension farm economist who conducts the survey. Duffy said the 22 percent increase recorded this year is the greatest one-year increase since 1976, and marks a new record for the fifth year in a row. Since the year 2000, Iowa land values have increased an average of $2,051 per acre, more than a 100 percent increase over the 2000 average value of $1,857.

The increases in values were reported statewide, with the survey recording averages above $5,000 an acre in five counties, and between $4,000 and $5,000 an acre in 51 counties. Nineteen counties reported increases of more than 25 percent, and 59 counties had increases between 20 and 25 percent (map, click to enlarge).

Duffy noted that some of the smaller percentage increases occurred in the counties and crop reporting districts along Iowa’s eastern and western borders. He said this reflects the impact of local demand for corn from ethanol plants. Counties along the border rivers previously received the best prices for crops due to low transportation costs to gulf port markets, but now those crops are being used locally by the ethanol plants, which is driving up prices in interior counties.

Duffy said he frequently is asked whether the land market will crash, and how high it might go before it tops out. He also is questioned about the impact of the weakening dollar, the new farm bill, and the current subprime mortgage crisis.

The world of agriculture as we know it here in Iowa has changed. Where the changes will settle out and when is not known. My general feeling is that the land market will remain strong for at least the next five years. We have seen a fundamental shift in demand for corn due to ethanol production. I don’t think this demand will diminish in the near future. - Mike Duffy, ISU Extension farm economist

Of the nine crop reporting districts in the state, northwest Iowa reported the highest average value at $4,699 per acre. The lowest average in the state was in south central Iowa at $2,325 per acre. North central Iowa was the leader in percentage increase at 25.3 percent, while east central Iowa had the lowest percentage increase at 14.7 percent:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: ethanol :: biodiesel :: farmland :: Iowa :: United States ::

The highest county average in the state was Scott County at $5,699 per acre, while Decatur County was lowest at $1,828 per acre. Sioux County led the state with the largest dollar increase at $1,142 per acre, while Floyd County had the largest percentage increase at 30.3 percent.

Low grade land in the state averaged $2,655 per acre, an increase of $460 or 21 percent over the 2006 survey. Medium grade land averaged $3,666 per acre, a $655 increase or 21.8 percent. High grade land averaged $4,686 per acre, an increase of $851 or 22.2 percent.

Survey participants were asked to indicate positive and negative factors that affected land prices during 2007. Good grain prices was by far the most frequently mentioned positive factor, listed by 35 percent of the respondents. Another 10 percent mentioned low interest rates as a major factor.

Three negative factors impacting land values were listed by more than 10 percent of the respondents. They included high costs for the inputs needed to grow crops, listed by 25 percent; high land prices in general, listed by 12 percent; and a concern over how long the market would remain at high levels, listed by 11 percent.

Thirty-seven percent of the respondents to this year’s survey reported more land sales in 2007 than in the previous year. That was the highest percentage since 1988. Buyers were existing farmers in 60 percent of the sales, and investors in 34 percent of the sales, essentially unchanged from the previous year, but down considerably from a decade ago when existing farmers represented nearly 75 percent of the buyers.

Data on farmland sales has been collected by Iowa State University annually since 1941. About 1,100 copies of the survey are mailed each year to licensed real estate brokers, ag lenders, and others knowledgeable of Iowa land values. Respondents are asked to report values as of Nov. 1. Average response is 500 to 600 completed surveys, with 499 usable surveys returned this year. Respondents provided 668 individual county estimates, including land values in nearby counties if they had knowledge of values in those counties.

Crossing the pond
Farmland will become a very valuable resource in the future global bio-economy. Industrial countries have already used up most of their suitable acreage and can expect a continuous rise in prices. Some have warned that new farmers will find it increasingly difficult to start a business because of this. However, in both Africa and Latin America, farmland is abundant and far less costly.

Some adventurous people will want to cross the Atlantic or the Mediterranean to start up in the bioenergy and agriculture sector in Africa. Tens of thousands of landless Chinese farmers are already doing this, encouraged by their government, with rising land prices in the People's Republic playing a key role (previous post).

The price of land is only one of many factors determining the viability of an agricultural enterprise. In increasingly science and tech driven agriculture its relative importance has declined over the decades. But the trend is now reversing. For farmers in emerging economies with scarce land resources (China, India) and whose farm practises are not comparable to the highly mechanised, intensive practises of their collegues in the West, venturing abroad might be an option.

So how much does farmland cost in African countries? Data are scarce and not kept up to date. But from what little data we have, the sheer difference in value can be sketched.

The World Bank Global Approach to Environmental Analyses (GAEA) made land price estimates back in 2000. The GAEA study attempts to build on earlier World Bank work that suggested that national land prices would be roughly equal to a multiple of per capita income. Estimates of land value calculated in this way were then adjusted to incorporate broader factors, such as proportions of pasture, cropland, forestland and arid land in the total land area, to arrive at indicative national land prices. In short, the land price data are very rough and only useful for broad comparative purposes.

The following tables were compiled from these data:












More on these data can be found here.

References:
Iowa State University Extension: 2007 Iowa Land Value Survey.

Iowa State University Extension: Average Value of Iowa Farmland Tops $3,900 an Acre in 2007 Survey - December 18, 2007.

Biopact: Ethanol boosts farmland prices in the US - December 22, 2006

Biopact: Landless Chinese farmers migrate to Africa in search of agricultural opportunities - December 02, 2007

Biopact: Land prices in Africa - September 15, 2006

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