Today's traditional soil amendment method was little more than a footnote in the book, but I'm intrigued by it nevertheless.  In southwest Guatemala, elderberry bushes (sauco) are interplanted amid vegetable crops.  Every year, the farmers cut back the bushes to stumps, and use the young leaves and branches to mulch around crop plants.  The leaves have a high nitrogen to carbon ratio (a lot like grass clippings), so they decompose rapidly, feeding the crop plants in the process.

The elderberry bushes in Guatemala are closely related to the elderberry bushes that grow wild here --- depending on who you talk to, the Mexican Elderberry (Sambucus mexicana) is either a subspecies or a closely related species to our Common Elderberry (Sambucus canadensis.)  We have elderberry bushes growing in our garden that I've tried to eradicate, but which keep sprouting back up from the stumps.  This year, I stopped the eradication campaign and instead decided to include the bushes as a mulch source in our forest garden since elderberry flowers are useful nectaries to attract beneficial insects.  I'm intrigued to read that some Guatemalan farmers also consider elderberries so important that they let them take up valuable crop space.