Root Examination

Posted on the side, and mentioned in previous postings is the comparison of the roots of two plants from the same patch of Canavalia. Canavlaia is otherwise known as the Jack Bean, and is one of the more prominant AVs that I am working with. The main reason for it's success here in Paraguayan Agriculture is because it grows very well with two cash crops, Corn and Mandioca. Canavalia not only fixes large amounts of nitrogen in the soil as a member of the Legume family, it also provide good above ground coverage and if planted densly enough it can eliminate the need foor weeding or "cleaning" the rows in between the cash crop.

As one can see in the two pictures, one group of roots is clean and has an absence of nodules, meanwhile, the other group of roots has a few little balls attached. These are nitrogen nodules and are the reason this plant is used as an AV. The test to make sure that nitrogen is present is to crush one of the nodules and see if it turns a brick reddish shade, if so, the is nitrogen present. These one did just that and it was a good thing too because it seems like only half of the plants in this section were actually fixing nitrogen.

The key to getting this nitrogen and other nutrients to stayin the soil is to cut the plant down to the soil just as it is about to flower. It is at this point that it has generated the most nutrients and if it is left any longer it will put those nutrients into the flower and then the seeds. I have currently done this and my patch of cut Canavalia is laying on the soil beginning a decomposition process. Also, under the soil the roots of the cut plat are dying and the nodules will then decompose releasing the nitrogen. This is an example of how an AV is used to revitalize soil and provide soil organic matter.