Free Nitrogen Fertilizer for Tropical Agriculture?


Nitrogen can be a problem- especially for farmers. Although our atmosphere is full of nitrogen gas (N2), the bond between the two nitrogen atoms is so strong that the molecule is virtually inert. But life needs nitrogen to grow - in fact all life requires nitrogen to be pulled apart and react. Which is why we throw excesses of fertilizers (much of it petroleum derived), onto our fields and crops every year- to encourage growth.

In nature, legumes have been the typical model for how plants can 'fix' nitrogen. Soybean, peas, ground nuts, alfalfa, clover are all common plants that associate with bacteria in their root systems to 'fix' nitrogen. The symbiosis between these plants and bacteria allows them grow in nitrogen depleted areas, as well as have the potential to increase nitrogen content of the soil. The planting of legumes can even be used for ecological, or field restoration. But the legume crops studied have mostly been limited to temperate climates.

Now a new type of nitrogen fixing symbiotic relationship has been discovered with important potential for tropical and temperate agriculture, as well as reducing our excessive use of petroleum derived fertilizers.


A joint group of researchers working with IRD (Laboratoire des Symbioses Tropicales et Méditerranéennes) have found a new paradigm in nitrogen fixation. Instead of the bacteria associating with the roots, this tropical symbiosis forms on the stems of the plants. This unique ability allows for the possibility of fixing higher quantities of nitrogen than those systems that are limited to just root structures.

The molecular biology behind the new symbiotic relationship is different from all other known associations for nitrogen fixing systems. This calls into question some basic assumptions that have long been held regarding nitrogen fixing symbiotic relationships. Further, the study shows that it may be possible to introduce this new type of symbiotic relationships into a broader range of crops than previously thought possible. Indeed- there are many symbiotic plant and bacterial relationships that we have never investigated. The direct applications of this discovery include holding off desertification, and increased food production in tropical regions. What other global problems might we discover a solution for if we took the effort to look? This research points to the importance of exploring our world, and learning how nature's systems operate in all regions of the world. We may be pleasantly surprised by the answers.


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