Maintaining adequate nutrient supply to maintain or enhance tree vigor and forest growth requires conservation of topsoil and soil organic matter. Sometimes nutrient amendments are also required to supplement inherent nutrient-pool limitations or replenish nutrients removed in harvested material. The goal is to maintain the productive potential of the soil and, when economically feasible and environmentally acceptable, enhance productivity where nutrient supply significantly limits growth. Nitrogen (N) is most frequently the limiting nutrient in Pacific Northwest forests, particularly on soils with low N pools (Gessel and Walker 1956; Heilman 1971; Turner et al. 1988, Chappell et al. 1991).