Some effects of changing soil chemistry on decomposition of plant litters and cellulose on a Scottish moor.

Nitrogen (N), phosphorus (P), calcium (Ca) and soluble carbohydrates (CHO) were each added at three levels to a moorland podzol, and the decomposition of three constrasting untreated substrates (Calluna vulgaris stems,Molinia caerulea leaves, and cotton strips) compared between treated and untreated plots. All soil treatments increased decay rates of all three substrates, except for the highest levels of P and CHO, which appeared to inhibit decomposition of cotton andMolinia. The results generally indicated use by the decomposers of nutrients or energy sources from the soil to aid decomposition of untreated substrates. With all additives (N, P, Ca, CHO) maximum degree of change was inversely related to substrate quality. All responses were nonlinear. Optimal levels of N and Ca were in the same order as substrate quality, i.e. optimum forCalluna