You're getting no response because the"state of the art" is not to use them at all. Instead they use solid top dressings . The dressings (ground malted barley, pelleted ferts etc) slowly become part of your humus layer by watering in and worms eating them. They add to the fertility of your soil over time. See how indirect that is? Your actions are 2 or 3 steps away from the plant. That seems to be a consistent principal with the organic guys.