Ad has more than 30 years experience in soil, plant and water analysis, and assessment of reliability of laboratory data, including consultancy in laboratory methods and quality management in developing countries.
Ad joined the International Soil Museum in Utrecht in 1971. His main focus while at ISRIC was on data quality, documentation, and the development and use of collections.
Ad retired in September 2016. Since that time, as a guest researcher, he provides special support on 'soil analytical methods' to the DATA (WoSIS) project.