Natural Resources
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Biofuels from land-rich tropical countries may help displace foreign petroleum imports for many industrialized nations, providing a possible solution to the twin challenges of energy security and climate change. But concern is mounting that crop-based biofuels will increase net greenhouse gas emissions if feedstocks are produced by expanding agricultural lands. Here we quantify the 'carbon payback time' for a range of biofuel crop expansion pathways in the tropics. We use a new, geographically detailed database of crop locations and yields, along with updated vegetation and soil biomass estimates, to provide carbon payback estimates that are more regionally specific than those in previous studies. Using this cropland database, we also estimate carbon payback times under different scenarios of future crop yields, biofuel technologies, and petroleum sources. Under current conditions, the expansion of biofuels into productive tropical ecosystems will always lead to net carbon emissions for decades to centuries, while expanding into degraded or already cultivated land will provide almost immediate carbon savings. Future crop yield improvements and technology advances, coupled with unconventional petroleum supplies, will increase biofuel carbon offsets, but clearing carbon-rich land still requires several decades or more for carbon payback. No foreseeable changes in agricultural or energy technology will be able to achieve meaningful carbon benefits if crop-based biofuels are produced at the expense of tropical forests.

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Environmental Research Letters
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Holly Gibbs
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Rising populations and incomes throughout the world have boosted meat demand by over 75% in the last 20 years, intensifying pressures on production systems and the natural resources to which they are linked. As a growing proportion of global meat production is traded, the environmental impacts of production become increasingly separated from where the meat is consumed. In this paper, we quantify the use of three important resources associated with industrial livestock production and trade - water, land, and nitrogen - using a country-specific model that combines trade, agronomic, biogeochemical, and hydrological data. Our model focuses on pigs and chickens, as these animals are raised predominantly in intensive systems using concentrated, compound feeds. The results describe the geographical patterns of environmental resource use due to meat production, trade, and consumption. We show that US feed, animal, and meat destined for export require almost as much nitrogen and land, and 20% more water, than products destined for domestic consumption. Model results also demonstrate that among various production factors, improvements in crop yields and animal feed conversion efficiencies result in the most significant reductions in environmental harm. By explicitly tracking the externalities of meat production, we hope to bolster suppliers' accountability and provide better information to meat consumers.

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Environmental Modeling and Assessment
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Marshall Burke
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Geographic information systems (GIS) present new opportunities for empirical agronomic research that can complement experimental and modeling approaches. In this study, GIS databases of irrigation practices for more than 4000 fields were compared with wheat yields derived from remote sensing for five growing seasons in the Yaqui Valley of Northwest Mexico. Significant yield effects were observed for both number and timing of irrigations, but not for reported water volumes, suggesting that proper timing is more important to yields than total water amounts. In most years, yield losses were observed when the second irrigation occurred more than 60 d after preplant irrigation, with an average loss of 11 kg ha-1 for each day above this value. Overall, we estimate that optimal timing and number of irrigations for all fields in Yaqui Valley could increase average yields by roughly 5%. Results varied by year, in part because of variability in growing season rainfall and in part because of variations in water allocations. Interactions with soil types were also evident, with greater yield variability attributed to irrigation on soils with higher clay contents. The results of this study provide new insight into specific causes of yield losses in farmers' fields, which can inform future field experiments, management, and water policy in this region. In general, empirical studies of large GIS databases can help to improve crop management, and meet the dual needs of higher yields and improved water use efficiency.

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Agronomy Journal
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David Lobell

Biofuel development contributes most effectively to rural income growth when you can have vertical integration. People all along the value chain have to be making money. The emerging connections between agriculture and energy markets are complex, but can be advantageous if handled carefully - Siwa Msangi

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This paper provides an original account of global land, water and nitrogen use in support of industrialized livestock production and trade, with emphasis on two of the fastest growing sectors, pork and poultry. Our analysis focuses on trade in feed and animal products, using a new model that calculates the amount of "virtual" nitrogen, water and land used in production but not embedded in the product. We show how key meat importing countries, such as Japan, benefit from "virtual" trade in land, water and nitrogen, and how key meat exporting countries, such as Brazil, provide these resources without accounting for their true environmental cost. Results show that Japan's pig and chicken meat imports embody the virtual equivalent of 50% of Japan's total arable land, and half of Japan's virtual nitrogen total is lost in the US. Trade links with China are responsible for 15% of the virtual nitrogen left behind in Brazil due to feed and meat exports, and 20% of Brazil's area is used to grow soybean exports. The complexity of trade in meat, feed, water and nitrogen, is illustrated by the dual roles of the US and the Netherlands as both importers and exporters of meat. Mitigating environmental damage from industrialized livestock production and trade depends on a combination of direct pricing strategies, regulatory approaches and use of best management practices. Our analysis indicates that increased water and nitrogen use efficiency and land conservation resulting from these measures could significantly reduce resource costs.

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Ambio
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Marshall Burke
Rosamond L. Naylor
Walter P. Falcon
Henning Steinfeld

Conference report

Agriculture is the human enterprise most dependent on climate and natural resources, and is thus the sector that has the most to gain or lose from short- or long-run changes in the level or variability of climate. A growing literature seeks to understand the probable effects of climate change on agriculture, and improvements in our understanding of climate dynamics and crop response has begun to reduce some of the uncertainties inherent in projecting future impacts on agriculture. Nevertheless, there has been scant research conducted on the climate impacts on various crops and agroecosystems of central importance to the global poor. Furthermore, much of the existing literature assumes that farmers will automatically adapt to climate change and thereby lessen many of its potential negative impacts, taking for granted the monumental past efforts at the collection, preservation, and utilization of plant genetic resources on which much of farmer adaptation has historically depended.

Given potentially large changes in global temperature, regional precipitation patterns, and extreme weather events, we believe it is dangerous to assume that adaptation of cultivars will happen automatically. Extensive crop breeding that relies on access to genetic resources will almost certainly be required for crop adaptation under conditions of global climate change. Furthermore, substantial knowledge and insight is needed to gauge what types of diversity now exist in the gene banks, and what will be needed in the future. Fundamental questions remain to be addressed, for example: How are regional patterns of climate expected to change in the future, and how will these changes affect agro-ecosystems around the world? There are also several strategic investment issues to consider--which traits, which crops and which regions should be central to strategic decisions on ex situ genetic conservation? What steps should be taken to conserve the genetic diversity of the important but neglected minor crops where the number of accessions is currently low? Answers to these questions will be critical for promoting food security and ensuring human survival, and to date have received little or no attention in the scientific literature or broader policy arena.

This conference will seek to answer three main questions:

1) What and where are the largest threats to agro-ecosystems under future climate change? Here we will seek to identify both the nature and the location of the largest probable threats, a topic that to date has not been systematically undertaken for certain areas of interest.

2) Taken individually and together, what do these threats imply for crop genetic diversity on a regional or global level? I.e. which traits, which crops and which regions appear central to strategic decisions on ex situ genetic conservation?

3) What is the current state of genetic conservation with respect to these threats, and what does this imply about the sequencing of future efforts at ex situ conservation focus? For example, are there a set of minor crops important to food security that are both poorly represented in the gene banks and under great threat from future climate change?

Particular attention will be paid to those crops and cropping systems on which food insecure populations currently depend, and who would be least able to adapt in the absence of concerted public action to the contrary. We expect that this effort will be the first serious attempt to link crop genetic resource conservation to climate change and variability.

» A news article on recent investments being made by the Global Crop Diversity Trust, decisions which were informed by the Bellagio meeting.

Bellagio, Italy

Conferences

Most reduction fisheries that produce fishmeal and fish oil have already reached or exceeded sustainable catch levels and will be placed under further pressure as the aquaculture industry grows. At the same time that research into alternative sources of nutrition for piscivorous aquaculture species is progressing, several laws and regulations are taking shape that address the issue of aquaculture feed practices, including the U.S. National Offshore Aquaculture Act (H.R. 2010, S. 1609), the California Sustainable Oceans Act (SB 201), and the development of organic aquaculture standards by the National Organic Standards Board (NOSB). Other nations with expanding aquaculture industries are also beginning to take notice of this issue and are investigating alternative feed sources.

At this pivotal time, the Stanford meeting will bring together a small group of forward-thinking researchers, environmental non-profits, aquaculture producers, feed developers, and others who are striving toward sustainable feed solutions. The goal is to develop recommendations and a guiding direction for achieving sustainable feed inputs, incorporating current science, economics, and policy. The meeting seeks to:

  • Analyze current and future feed demands in the marine aquaculture sector. What percentage of fishmeal and fish oil inclusion is typical in feeds, and how much can that percentage be reduced?
  • Assess the role of conventional fishmeal and fish oil and alternative sources of nutrition, such as krill, algae, other microbes, terrestrial plants, by-catch, and seafood and poultry processing wastes, both now and in the future. What are the prospects for continued use of wild-caught fish and how can these conventional feed sources be used more responsibly? What are the environmental impacts of each of the resources? What is the state of scientific knowledge, development, and availability of alternatives? How will market dynamics impact the transition from fishmeal and fish oil to alternative proteins and oils?
  • Identify research needs and areas of high promise. Discuss how to encourage the research, development, and use of sustainable, alternative feed ingredients in aquaculture.

We hope the meeting will facilitate the cross-fertilization of ideas on sustainable feeds from people in different sectors and begin to provide some clarity and direction useful to policymakers. Although many experts have acknowledged the problem of increasing feed demands, and while alternative feed sources are a growing research field, there are few specific recommendations on how to achieve sustainable feed inputs. From the discussion at this workshop, we intend to produce specific recommendations to guide legislation and regulation on feeds, with the goal of improving the sustainability of aquaculture feed practices.

FSE - Stanford University

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