Truth: GM has not delivered nitrogen-efficient crops and better solutions are available

Myth at a glance

The production and use of nitrogen fertilizer in chemically-based agriculture is energy-hungry, emits climate-damaging greenhouse gases, and causes water pollution.

The cost of nitrogen fertilizer is tied into the cost of natural gas, as the production process uses large amounts of this non-renewable fossil fuel. Prices have risen since 2009 and that trend will likely continue.

For years, the notion has been promoted that crops could be genetically engineered for high nitrogen use efficiency (NUE), so that they require less nitrogen fertilizer. But this remains an empty promise.

In contrast, conventional breeding has successfully delivered significant improvements in NUE in important crops.

Studies show that organic, low-input and sustainable farming methods are the key to nitrogen management. These methods could provide enough nitrogen to replace that derived from fossil fuels, with no additional agricultural land area required. Nitrogen pollution of water would also be greatly reduced.

Synthetic nitrogen fertilizer is used in GM farming, as in all chemically-based agriculture. There are many problems associated with its production and use. The production process uses large amounts of natural gas, a non-renewable fossil fuel.1 Nitrogen fertilizer production can account for more than 50% of the total energy used in industrialized agriculture.2

Nitrogen fertilizer produces greenhouse gases at the time of manufacture and again when used on fields, giving off nitrous oxide, a greenhouse gas 300 times more potent than carbon dioxide.3 Fertilizer-intensive agriculture is by far the largest source of human-created nitrous oxide emissions in the United States3and this is likely to be the case in any country where chemically-based agriculture is practised.

The profitability of farming is highly dependent on the cost of fertilizers and the cost of nitrogen fertilizer is tied to natural gas prices.1 In Canada, a major producer country, the price of nitrogen fertilizer reached a record high in 2008 and has consistently risen after a brief drop in 2009.4 According to some analysts, peak gas, the point at which the maximum rate of gas extraction is reached and supplies enter terminal decline, is expected to arrive around 2020,5 pushing up prices still more. Already the industry is ramping up expensive and environmentally damaging strategies, such as fracking, for improving the “efficiency” of natural gas extraction.

For all these reasons, agriculture cannot continue to depend on synthetic nitrogen fertilizer. Other ways of managing nitrogen must be found.

Some plants, including most legumes (the bean family of plants, which includes soy and peanuts), fix nitrogen directly from the air with the help of nitrogen-fixing bacteria associated with the plant’s roots. But other crops, such as wheat and barley, cannot do this and need to be fed nitrogen through the soil.

For years, the notion has been promoted that genetic engineering can produce crops with high nitrogen use efficiency (NUE) that require less nitrogen fertilizer.6,7

But GM technology has not produced any commercially available NUE crops. In contrast, conventional breeding has successfully delivered significant improvements in NUE in a number of crops.6 Estimates for wheat from France show an increase in NUE of 29% over 35 years,8 and Mexico improved wheat NUE by 42% over 35 years.9

Studies show that organic, low-input and sustainable farming methods are the key to nitrogen management. Such methods include the planting of nitrogen-fixing legumes, either in rows as cover crops (crops planted to manage soil quality and fertility), or between the main crop rows, or in a crop rotation. This makes growth-promoting nitrogen available to other plants growing nearby at the same time or planted in subsequent cropping seasons. A study calculated that these methods could provide enough nitrogen to replace that derived from fossil fuels, with no additional agricultural land area required.10

Other study findings include:

  • Planting legumes on severely degraded land in Brazil successfully fixed nitrogen in soil, restoring soil and ecosystem biodiversity in the process.11
  • Maize/peanut intercropping (growing two or more crops in close proximity) increased soil nitrogen and other nutrients, increased the growth of beneficial soil bacteria, and was expected to promote plant growth, as compared with monoculture, in experiments carried out in China.12

Agroecological methods of managing nitrogen solve another major problem associated with the application of synthetic nitrogen fertilizer – loss of soil nitrogen though agricultural runoff. In the runoff process, nitrogen leaches from soil in the form of nitrate, polluting groundwater. It can get into drinking water supplies, threatening human and livestock health.

Agroecological, organic, low-input, and sustainable farming practices have been found to reduce soil nitrogen losses in the form of nitrate by between 59 and 62% compared with conventional farming practices.13 The result was reduced nitrate pollution and better conservation of nitrogen in soil.

Conclusion

For years, the notion has been promoted that crops could be genetically engineered for high nitrogen use efficiency (NUE), so that they require less nitrogen fertilizer. But this remains an empty promise.

In contrast, conventional breeding has successfully delivered significant improvements in NUE in important crops.

Studies show that organic, low-input and sustainable farming methods are the key to nitrogen management. These methods could provide enough nitrogen to replace that derived from fossil fuels, with no additional agricultural land area required. Nitrogen pollution of water would also be greatly reduced

References

  1. Funderburg E. Why are nitrogen prices so high? Ag News Views. 2001. Available at: http://www.noble.org/ag/soils/nitrogenprices/.
  2. Woods J, Williams A, Hughes JK, Black M, Murphy R. Energy and the food system. Philos Trans R Soc Lond B Biol Sci. 2010;365:2991–3006. doi:10.1098/rstb.2010.0172.
  3. US Environmental Protection Agency (EPA). Nitrous oxide. 2014. Available at: http://www.epa.gov/nitrousoxide/scientific.html.
  4. Agriculture and Agri-Food Canada. Canadian farm fuel and fertilizer: Prices and expenses (March 2012). Mark Outlook Rep. 2012;4(1). Available at: http://bit.ly/1h2pqD0.
  5. Mobbs P. In: Energy Beyond Oil. Trowbridge, Wiltshire, UK: Cromwell Press; 2005:54.
  6. Gurian-Sherman D, Gurwick N. No sure fix: Prospects for reducing nitrogen fertilizer pollution through genetic engineering. Cambridge, MA; 2009. Available at: http://www.ucsusa.org/assets/documents/food_and_agriculture/no-sure-fix.pdf.
  7. McAllister CH, Beatty PH, Good AG. Engineering nitrogen use efficient crop plants: the current status. Plant Biotechnol J. 2012;10(9):1011-1025. doi:10.1111/j.1467-7652.2012.00700.x.
  8. Brancourt-Hulmel M, Doussinault G, Lecomte C, Bérard P, Le Buanec B, Trottet M. Genetic improvement of agronomic traits of winter wheat cultivars released in France from 1946 to 1992. Crop Sci. 2003;43(1):37–45. doi:10.2135/cropsci2003.3700.
  9. Ortiz-Monasterio I, Sayre KD, Rajaram S, McMahon MA. Genetic progress in wheat yield and nitrogen use efficiency under four nitrogen rates. 1997. Available at: http://repository.cimmyt.org/xmlui/handle/10883/2316.
  10. Badgley C, Moghtader J, Quintero E, et al. Organic agriculture and the global food supply. Renew Agric Food Syst. 2007;22:86–108.
  11. Chaer GM, Resende AS, Campello EF, de Faria SM, Boddey RM, Schmidt S. Nitrogen-fixing legume tree species for the reclamation of severely degraded lands in Brazil. Tree Physiol. 2011;31(2):139-49. doi:10.1093/treephys/tpq116.
  12. Zhang JE, Gao AX, Xu HQ, Luo MZ. [Effects of maize/peanut intercropping on rhizosphere soil microbes and nutrient contents]. Ying Yong Sheng Tai Xue Bao. 2009;20(7):1597-602.
  13. Oquist KA, Strock JS, Mulla DJ. Influence of alternative and conventional farming practices on subsurface drainage and water quality. J Env Qual. 2007;36(4):1194-204. doi:10.2134/jeq2006.0274.