Martin is Director of the Sustainable Soils and Crops Strategic Area at Rothamsted Research. His research seeks to increase our understanding of mineral nutrient dynamics in agriculture and food systems. A particular focus is on improving the nutritional quality of crops for human and livestock diets. For this, he collaborates with soil and crop scientists, human/animal nutritionists, and social scientists. It also includes the development of long-term research and training partnerships with higher education and government research institutes in several countries in Africa.
From 2017–2021, Martin was a part-time Senior Research Fellow (Agriculture & Food Systems) in the Research and Evidence Division of the Foreign, Commonwealth & Development Office (FCDO); he retains a Chair in Plant Nutrition at the University of Nottingham.