The influence of Dan H. Yaalon: His impact on people

• Dan Yaalon was one of the most accomplished pedologists of the 20th century.
• Yaalon also influenced many other soil scientists and geologists.
• Personal testimonies here tell of Yaalon's influence.
• A distinguished scientist's accomplishments include their impact on others.

There are many ways to measure the accomplishments of a scientist, such as papers and books published, citations, and prestige of journals published in, but we rarely gather information that allows us to evaluate the variety of influences that individual scientists have on the careers of others. Dan H. Yaalon was one of the most accomplished pedologists of the 20th and early 21st centuries. In this paper we gather personal testimonials of the impact Yaalon had on scientists working in the areas of interest to Yaalon. This allows us to qualitatively evaluate the impact of an influential scientist on his field through the ways that he influenced the career choices of others. We found that this influence occurred through 1) personal, face-to-face contact, 2) written correspondence between Yaalon and other scientists, both through letters and through email, and 3) Yaalon's written record itself, without any direct, personal interaction between Yaalon and the other scientists. This influence took place over multiple generations of scientists, ranging from individuals who are currently retired to those who are just now in the very early stages of their scientific careers. The Yaalon example makes clear how successful scientists make significant contributions to their fields of interest well beyond those indicated by commonly used measures.