Thursday, 14 July 2011

The Wonders of Legumes

Yes a lot of awful things are happening out there, and the weather in Eastern Canada anyway is cold and wet, but certainly not the extremes of drought and heat in many parts of the world.  So no complaining here. In fact I want to celebrate a family of vegetables called legumes. You know them as peas, beans, soybeans, lentils, clover, alfalfa, lupins, peanuts, and there are more. What makes them special is the symbiotic relationship they have with a soil bacteria called  rhizobia. (the vast majority of bacteria are good for us). Here's what they look like:

The bacteria are capable of fixing (capturing)  nitrogen from the air. Nitrogen is necessary to produce crops and used to come essentially from animal manure, and bat quano. In the mid 1800's a German chemist called Justus von Liebig discovered the important role nitrogen plays in plant growth, and was the first to create chemical fertilizers (now made from natural gas) which have been the boon and bane of farming: huge productivity gains, accompanied by nitrate pollution of waterways and dead zones everywhere these synthetic fertilizers are used. (search for nitrates in earlier posts).

That's what makes legumes so special. There's really no need for chemical fertilizer (in fact too much available nitrogen suppresses the production by the bacteria).  All of the legumes make excellent crops for experienced or beginning gardeners. Legumes generally have higher protein levels than other vegetables (scientists think it's because of the extra nitrogen which is a key component of protein)and crops like beans can be harvested and re-harvested over several weeks. One trick I've found is wide-row planting. Because fertility isn't an issue, they can be bunched together and still be very productive. As well the wide rows shade the ground and keep weeds at a minimum, and the very best thing is you can stand in one place and harvest a lot before moving down the row. Here's what it looks like. (the peas are doing well in the cold, damp summer of 2011, beans are a little slow, they like warmer weather.)

The holy grail for many plant biologists would be developing grains that would attract the rhizobia bacteria to their roots, then you'd be able to grow wheat, barley, etc, with little or no need for chemical fertilizer, and all the cost and environmental damage that come along with it. It's this promise (I keep reading that it's a long-shot)  that maintains many people's interest in GMO research. Scientist say there's no way this would happen with conventional breeding techniques, but might through genetic engineering. A good enough reason to keep GMO research going?

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