Bird, Could be that the manure may have had enough nitrogen in it to make up for the loss to decomposing wood chips. If it works that's great. Although I do like to use commercial fertilizers, I still like to mix lots of manure, compost and other organics in the soil also because the organic matter does keep the soil loose and easy to work. But usually I'll do that in the fall and then till it under come spring. I also feel the same way you do about insecticides-I use them elsewhere, but am very sparing with their use in the garden. Some pests can't be dealt with any other way though.