Impacts of pH on mechanisms and rates of carbon and nitrogen mineralisation: a review

Decomposition of soil organic matter (SOM) plays an important role in nutrient (re)cycling in all ecosystems of the world. Decomposition of SOM in soils is mainly a soil microbial process. Soil pH affect many soil characteristics which in turn affect the microbial indicators, such as microbial composition, biomass and growth and thereby the microbial activity. This activity governs the mineralisation processes of soil organic matter and is strongly pH dependent. This report gives first an overview of the mechanisms behind impacts of pH on these microbial indicators as well of the impacts of pH on microbial indicators themselves of which pH influences on the major decomposition process do get much attention. Next, it presents empirical quantitative relationships between pH and the mineralisation processes respiration, ammonification and nitrification. Finally, the report gives recommendations on how to include pH dependent relationships in SOM decomposition models.