I've built four additional raised beds for my garden, and put a lot of tree branches and cow manure at the bottom.
The problem is, the beds are two feet deep (24" sides, I mean), and I had intended on filling them to within 4 inches of the top with soil (with woodchips on top).
Basically, if I have eight inches of soil on top of the tree branches, and if whatever I plant in the beds don't have roots that reach that deep, do the shallow rooted plants still benefit from the nutrients?
Or should I churn up the beds in three years to bring the nutrients to the surface?
(A quick google shows that tomato plant roots go 12+ inches, so I probably don't have anything to worry about, but am still curious. Also, I'll be sure to put good material in the upper eight inches, not just soil.)