The global production of biofuel has greatly increased due to energy security concerns. Over the past two decades, ethanol production in the United States has grown 15–20% per year to meet the increased demand for renewable fuels (U.S. Energy Information Administration 2011). The majority of ethanol produced within the United States comes from corn sugars. Approximately 3% of the corn harvest was needed to meet ethanol demand in 1990, but this percentage grew to 37% by 2010. Due to the increased demand for more renewable energy sources to replace environmentally harmful fossil fuels, policies have been enacted to promote the increased production of biofuel. One of these policies is the U.S. Renewable Fuel Standard, which aims to increase biofuel production to 36 billion gallons by 2022. It has been suggested that not only direct effects, but also indirect effects, of biofuel production should be taken into account (Melillo et al. 2009). The direct effects of biofuel production include greenhouse gas (GHG) emission reductions, while indirect effects may be evident in land use changes. It has also been argued that an increase in corn ethanol production will lead to a reduction in food exports and deforestation in other nations (Searchinger et al. 2008). Due to the increase in the availability of U.S. agricultural data, researchers no longer have to rely on theoretical evidence; rather, now researchers can use real agricultural data to determine the effects of increases in ethanol production. However, these data may not be sufficient enough to fully assess indirect land use changes in the United States (Wallington et al. 2012). —Shelby Long
Wallington, T. et al., 2012. Corn Ethanol Production, Food Exports, and Indirect Land
Use Change. Environmental Science and Technology 46, 6379–6384.
Wallington et al. analyzed the direct and indirect effects of the United States’ recent increase in biofuel production using available agricultural data through 2010. They examined data on the global production, import, and export of agricultural commodities published by the United States Department of Agriculture Foreign Agricultural Service (USDA-FAS). They also analyzed monthly data on energy statistics and production of fuel ethanol published by the United States Energy Information Administration (EIA). Both sources of information were used by Wallington et al. to gain insight on the history of ethanol production and agriculture exports dating as far back as 1960. Researchers examined agricultural productivity, corn ethanol production, and agricultural exports of the Unites States. They acknowledge that between 2000 and 2010 the increase in use of corn for ethanol was accompanied by an increase in corn harvest. However, researchers do not suggest that the increase in harvest was necessarily due to the increase in corn ethanol production.
Wallington et al. recommend that future models need to account for increased yields in the United States and other countries due to agriculture technology improvements. They suggest that these improvements are the result of increased biofuel production in the United States. If this is the case, then researchers suggest decreases in land use outside of the U.S. would result, therefore, translating into a negative, favorable land use change burden. In the long term, increases in demand for ethanol could lead to lower costs and higher yields. In the short run, more intensive land use, investment in new production equipment, weather variability, movement of corn onto the better land, and increases in rotation of higher yielding crops (soy and corn) may take place.
Wallington et al. determined that where there was an increase in ethanol production there were no obvious changes in corn and wheat exports in the past decade. On the other hand, soybean, chicken, and pork exports have increased significantly over the past decade. Annual corn exports showed no changes, as they remained at approximately 50 million tonnes. There has also been a large increase in production and exports of distiller’s dry grains (DDG) over the past 10–15 years. DDG is a co-product of ethanol production and is used as an animal feed. Therefore, a reduction in demand for animal feed produced outside of the U.S. could be the result of increased biofuel demand in the U.S. This reduction in demand for animal feed would lead to a negative indirect land use change. The corn harvest has exhibited an upward trend over the past 50 years, increasing by about 2% per year. Along with other factors taking place, the increase in harvest over the past 10 years was accompanied by an increase in use of corn ethanol. There is no trend in the total harvested area of crops such as corn, soy, wheat, oats, and barley. This may also indicate that there was no increase in the land devoted to the cultivation of these crops. There is no significant correlation between U.S. ethanol production and corn exports in the past two decades. Even if there was a correlation it could not be determined for certain whether one was the cause of the other. Similarly, data on exports of meat and grains do not support the idea that corn ethanol production affects food exports.
A past study predicted that a 56 billion liter increase in corn ethanol production would lead to a decline in corn, wheat, soybean, pork, and chicken exports by 62%, 31%, 28%, 18%, and 12% (5). However, these levels of decline in exports were not seen as a result of the 43 billion liter increase in production over the past decade. Another recent study proposed a model on indirect land use changes associated with an increase in corn ethanol production (Hertel et al. 2010). The modeled increases in ethanol production were very close to the increase that took place between 2000 and 2010. The model also predicted a net increase of 0.41% in coarse grain yield and a 17% decrease in coarse grain exports due to increases in ethanol production. However, the historical 15% increase in ethanol production was 40x greater than the predicted 0.41% increase in yield of corn.
The increases in ethanol production over the past decade have been accompanied by increases in harvest. These increases in harvest are largely the result of improved yield per acre, increased acreage use, genetic improvements/hybrid plant breeding, and improved crop management (22). There are two main arguments related to the effect of increased biofuel production on agricultural yields. The first argument is that the increased market for corn ethanol production has not led to increases in agricultural yields. This argument may be somewhat supported by the historical trend of corn yields over the past decade, which shows no change. However, there are many other factors, such as population growth, dietary trends, economic growth, energy price fluctuation, and international export/import policy changes that may have been the cause of any changes in corn yields and demand. Any changes are not necessarily due to the increases in ethanol production. The other argument is that increases in demand for corn for ethanol production has made some contribution to changes in agricultural yields. This argument is plausible because increases in demand and supply for corn, and interest in research and development of hybrid plants and improved agricultural practices are likely to lead to increases in corn yields. Approximately 12 billion gallons of ethanol are made annually, which requires approximately 100 million tonnes of corn. Approximately 30 million tonnes of DDG are produced as a result, and 1 tonne of DDG displaces approximately 1.2 tonnes of corn as animal feed (Arora et al. 2010). If biofuel production does not contribute to increased corn yields, then there would be an indirect land use change due to increased corn ethanol production in the United States. On the other hand, if biofuel production is responsible for all of the increased corn yields in the U.S., but none of the increased yields observed in the rest of the world, then there would be a small indirect land use change. If biofuel production was responsible for all of the increases in U.S. corn yields and some of the increased yields in the rest of the world, then there would be negative indirect land use change due to corn ethanol production in the U.S.
Such large differences in corn yields of the U.S. and the rest of the world indicate that improved agricultural practices should be adopted by other countries, such as improved soil management, irrigation, fertilizer use, and farm machinery. Due to the detailed agricultural data now available to researchers, new perspectives can be gained about crop yield changes and their effects. However, further investigation must be conducted in order to gain a better understanding of the land use changes that may take place as a result of increased ethanol production. In order to decrease the indirect land use changes in other countries as a result of higher biofuel production in the U.S., intensification of agricultural activities outside of the U.S. should be promoted. Wallington et al. maintains that further investigation must take place concerning indirect land use changes resulting from ethanol production in order to determine what steps must be taken to decrease the impacts.
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Searchinger, T. et al., 2008. Use of U.S. croplands for biofuels increases greenhouse
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