Ammar began his career as an assistant professor and research staff economist at the Department of Economics,
Yale University before moving to the Faculty of Economics of
Thammasat University as a
Rockefeller scholar on the advice of
Puey Ungpakorn who was then dean of faculty. He was a visiting professor at the Food Research Institute of
Stanford University as well as a research fellow with the
International Food Policy Research Institute in Washington, D.C. He was a founding member of the
Thailand Development Research Institute (TDRI), serving first as program director for agriculture and rural development and then as its president from 1990 to 1995. Following his tenure, he held the title of distinguished scholar at the TDRI. Ammar was an expert in
Thai rice policy,
Thai agricultural economics, and
development economics. He has been described as "one of the country's top technocrats". His work together with Suthad Setboonsarng formed the definitive study of Thailand's agricultural price policy in the 1980s. Ammar was also appointed member of the
National Legislative Assembly following the
2006 coup d'état. == Publications ==