How much organic material is enough?
Most garden soils would benefit by the addition of more organic material but it can be overdone. Soils with too much organic material can be excessively soft and fail to give plants, particularly trees, a sufficient foothold or anchor. Excessively high levels of organic material could also keep the soil excessively moist. 15% by volume organic material is about right for most gardens. Native soils frequently run as low as 3% by volume organic.
