 His research has developed biomolecular and isotopic methods to characterise soil organic matter and to understand how soil organisms impact the cycling of organic matter.The wider aim of this research is to produce better models for nutrient cycles, which are central to understanding the effects of global warming and intensive agriculture.This study of organic matter has also been applied to palaeoenvironment and palaeoclimatic reconstruction, using sedimentary archives such as ocean sediments and peat bogs.