This image is the first of two that show the trench system...basically you dig a trench about a foot or more deep and you fill it with any growing medium combination that works best for what you are growing. One good mix that will not break down is one known as Mel's Mix created by Mel Bartholamew but he gives no credit to native Americans in any aspect of garden (except for a weird referance to a rain dance?), which I just think is wrong...so I change his mix quite a bit. ...he wrote Gardening by the Foot and had a show on T.V. ...1/3 pearlite (or vermiculite), 1/3 pete moss, and 1/3 a combination of 7 manures.