IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...

17 th International Congress on Nitrogen Fixation
Fremantle, Western Australia
27 November – 1 December 2011
Session Details: Thursday 1 December 2011
Plenary Session
0900 – 1030
Authors: Perrin H Beatty 1 , and Allen G Good 1
1 Department of Biological Sciences, Biological Sciences Building, Edmonton, Alberta,
Canada, T6G 2E9
Presentation Title: Environmental and economic impacts of biological N2 fixing cereal crops
Presentation Time: 0930 - 1000
We will need to feed a large future global population using less arable land while coping with rising fuel prices
and environmental pollution inherent to the increase in N fertilizer use in intensive farming practices. Cereal
crops tend to have low nitrogen use efficiency and require N fertilizer application (synthetic or organic) for high
yields. A portion of the applied N fertilizer will be lost to the plant by either uptake competition from soil microbes
resulting in nitrification/denitrification and eventually loss back to the atmosphere, leaching into waterways and
ammonia volatization. However, cereal crops that can fix their own nitrogen would bypass the N losses to the
environment while still providing N to the plants.
The engineering of N2 fixing cereal crops, by introducing either diazotrophic bacterial nodulation within cereal
crop roots or nitrogenase genes (nif genes) directly into plant chloroplasts or mitochondria, is an attainable future
goal (Beatty and Good, 2011). Both approaches are expected to take multiple years to completion, although
step-wise advances in the ability of cereal crops to fix N2 are expected along the way. The rate of N2 fixation
using either approach is predicted to be similar to the rate measured in rhizobial-legume symbiosis, or higher.
This suggests that, if we can successfully engineer BNF cereal crops, the requirement for cereal crop N fertilizer
application will be reduced, or potentially, even eliminated.
The environmental and economic impacts of N2 fixing cereal crops are assessed in this paper, such as the
environmental effects of using less N fertilizer on the atmosphere and aquatic ecosphere, the economic
implications for farmers, as well as the potential implications to the plants‟ N economy.
Beatty PH & Good AG (2011). Cereal crops and biological nitrogen fixation; future prospects. Science, July 24.
98
2011