From what I remember there are many different species ... yuk!
http://en.wikipedia.org/wiki/N...
And two things about the mustard is it has to be dug into the ground as soon as it is cut to ensure fumigation otherwise the gases escape into the air. Mike told us you have to cut it, till it in really really fast, and tamp the soil down. He said you can actually see the gases rising if you catch it in the right light ... and he of all people should know what he was talking about ... he was the Plant Pathologist from the University of Guelph.
There is a commercial product that has been produced called MustGrow ... we're checking it out too.
Meanwhile if you want to know more go to
http://www.sare.org/Learning-C...
some of their books are available free as PDF downloads
Some of the titles ...
- Managing Cover Crops Profitably <-- very very interesting content, tables, etc.
(see page 32 for info about cover crops that kill nematodes- mustard, marigold, etc.
and see charts on pp.67-72)
- Building Soils for Better Crops
- Crop Rotation on Organic Farms
etc.
You'd think we had a farm
