I am looking at tree guilds for my landscape and I was thinking about how to promote moisture retention for the trees. One of the things I was considering was to dig the hole for the tree a couple feet deeper than I need and line the bottom of the hole with branches, wood, leaf litter, and aged manure, then plant the tree on top of this bottom biosponge of material. However I was just reading in Carrots Love Tomatoes and in the fruit tree section she says that you shouldn't put any kind of biomatter in the soil under/around the newly planted tree. So I am curious what you guys think. Do you think it would work to hugel your trees when you plant them?
I am planning to put hugel trenches around my new trees when I next plant in the Fall. I don't think I want to put the hugel under the tree because of subsidence - I've noticed my hugel beds tend to sink over time and I don't want my trees to sink! But I don't mind if they have sunken rings around them because these will help trap run-off.