Having graduated from Faculty of Agronomy, Estonian Agricultural Academy, in 1954, he was conferred the degree of Candidate of Sciences on agricultural sciences (soil genesis and geography) by the Council of the Estonian Agricultural Academy, Tartu, Estonia in 1960. In 1974 Loit Reintam was awarded the degree of Doctor of Sciences on natural sciences (soil genesis and classification) by the Joint Council of the Siberian Branch of the USSR Academy of Sciences, Novosibirsk, Russia. Three years later he became a professor of soil science at Estonian Agricultural Academy. In 1990 he was elected Member of the Estonian Academy of Sciences in soil science. Since 1997 Loit Reintam was Professor Emeritus of Estonian University of Life Sciences. From 1964 to 1991 L. Reintam was President of Estonian branch of All-Union Society of Soil Science (predecessor of current Estonian Soil Science Society). In 1971...1977 he was Vice-President of the All-Union Society of Soil Science.

Loit Reintam was a teacher, scientist, leader and public authority whose teaching and advice were always of a high standard. As a leader he was influential, sharp and purposeful, and as an individual he was a charismatic personality who stood out amongst scientists of other countries. During his scientific activity he published nearly 600 scientific and popular scientific publications, taught students during 100 semesters, gave nearly 2000 lectures, speeches and comments at different institutions, regions, schools, etc. L. Reintam revised and evaluated hundreds of articles, papers and books, supervised and reviewed nearly 700 dissertations (Ph.D., D.Sc.). He was an expert and/or member of doctoral and attestation councils.

The field of interest of Loit Reintam was very wide – research into genesis, ecology, geography, classification, mineralogy, chemistry and granulometry of soils in Estonia and several regions (Far-East, Siberia, Central Russia) of forest zones, as well as studies into humus relationship and composition, functioning of plant-soil systems, the history of soil science, and application and teaching of forest and agronomic soil science. He represented the biopedological school, whose topics are genesis and ecology of plant-soil systems.

Loit Reintam was a member of several societies, such as International Union of Soil Science (IUSS), European Society of Soil Conservation (ESSC), European Soil Bureau Network (ESBN), Commission on Nature Conservation, Estonian Academy of Sciences, etc.

He was awarded several medals and honorary certificates. In 1998 Loit Reintam was awarded the 3rd class Order of the White Star. He was Honorary Member of the Dokuchaev Soil Science Society of Russian Academy of Sciences (since July, 2000) and Honorary Doctor of the Georgia State Agricultural University (since 2005).