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Homer D. Chapman

Professor of Soils and Plant Nutrition

UC Riverside

1898 - 2005


Dr. Homer D. Chapman, among the very few surviving veterans of World War I and persons living in three centuries, died at the age of 106 on April 4, 2005 at Regents Point retirement home in Irvine, California. His wife of 69 years, Daisy, preceded him in death at age 96 in 1999.


Following receipt of his PhD from the University of Wisconsin in 1927, Homer joined the University of California Citrus Experiment Station, later the site of the UC Riverside campus, as an assistant chemist. He was promoted to associate chemist and chemist in 1937 and 1944, respectively. In 1938 he was appointed chair of the then Department of Agricultural Chemistry and, later the Department of Soils and Plant Nutrition. He served as chair for 23 years until 1961 when he assumed a temporary appointment as Associate in the Rockefeller Foundation in India. Dr. Chapman served as acting cirector of the Experiment Station in 1951-52. He reached mandatory retirement age in 1966 but continued research, and lectures and traveled extensively until relocating to Regents Point in 1993. His teaching, research, and professional and public service career spanned seven decades. Probably his greatest disappointment in life was the loss of his driver’s license and thus loss of considerable independence at age 99.


Dr. Chapman pioneered the use of leaf analysis as a tool to diagnosis deficiencies and excess of elements in the nutrition of plants. Although his work was mainly directed to citrus crops, the technique was applied over the years to virtually all crops by Chapman and others. He was among the first to control the supply of nutrients to crops through the use of hydroponics. He developed methods for growing fruit bearing citrus trees in water cultures out-of doors. As a result of this work a great body of information concerning visual symptoms of mineral deficiency and excesses accumulated and leaf and soil analysis standards emerged. He is the author, co-author or editor of 4 books and more than 160 technical publications. While serving as a soils consultant on a US-AID project in Chile in 1957, Dr. Chapman recognized the need for a compendium on methods for the analysis of soils, plants and waters along with diagnostic criteria for soils and plants. To fulfill this need he co-authored with Parker F. Pratt a book entitled Methods of Analysis of Soils, Plants and Waters and an extensive edited volume on Diagnostic Criteria for Plants and Soils. Diagnostic Criteria for Plants and Soils has been reprinted 5 times and serves as the standard reference in the field.


Professor Chapman acquired a national and international reputation as an expert on the mineral nutrition of plants, particularly citrus crops. . He has presented invitational papers, plenary lectures and advised at universities, governmental agencies, professional society meetings and symposia throughout the world including Brazil, Canada, Australia, England, Italy, Spain, Morocco, Algiers, Tunisia, Israel, Pakistan, Malaysia, Japan, South Africa, Lebanon, Syria, Turkey, Thailand, Cambodia, Venezuela, and Taiwan. In 1954 he was invited by the Government of Brazil to present a plenary lecture on citrus mineral nutrition at the 2nd PAN American Congress of Agronomy in San Paulo and to visit and advise on major citrus growing areas of Brazil. In 1956-57 he spent a year in Chili as a soils consultant on a project sponsored by the US Agency for International Development and in 1961-62 served 6 months in India with the Rockefeller Foundation lecturing on soil, plant nutrition and citrus problems. In 1964 and 1974 Dr. Chapman was invited by the Ford Foundation to lecture and consult on citrus and other agronomic problems in Egypt. In 1976 he was asked by Ag International to access the feasibility of growing citrus using irrigation water made available from construction of the Aswan Dam in Egypt.


In 1968 Professor Chapman organized the first International Citrus Symposium as part of the centennial of the University of California, Riverside campus. The popular symposium attracted more than 800 delegates from 53 countries. The proceedings of the symposium comprising some 1800 pages in three volumes were published with Dr. Chapman as editor. Following the symposium the delegates decided that an International Society of Citriculture should be formed and appointed Dr. Chapman as chair the organizing committee. He almost single handedly completed the task and while serving as the Society’s secretary from 1970 to 1986 and is credited for its popularity and rapid growth. The first congress was held in Spain in 1973 with later conferences held in Florida (1977), Australia (1978), Japan (1981), Brazil (1984), Israel (1988), Italy (1992), South Africa (1996), USA (2000) and Morocco (2004). In recognition of his distinguished services to the Society Dr. Chapman was awarded its first Honorary Membership in 1981.


Professor Chapman received numerous professional and public service awards. In recognition of research and professional service he was elected fellow, American Association for the Advancement of Science in 1950; fellow, American Society of Agronomy (ASA) in 1955; Honorary Member, ASA in 1968; Honorary President, International Society of Citriculture in 1985 and the Albert G. Salter Memorial award in 1990. Professor Chapman was named Faculty Research Lecture at UCR in 1952; in 1969 he was awarded an Honorary L.L.D. by the University of California and in 1987 the Emeritus Faculty Award. In recognition of his scholarly contributions, service to his profession, and service to UCR and UC, the building in which he toiled for most of his career was named Chapman Hall. Professor Chapman served as president of the Western Soil Science Society and as chair, Soil Chemistry Division of the Soil Science Society of America. In addition to the societies mentioned above, Professor Chapman was a member of the American Society of Horticultural Science, International Organization of Citrus Virologist and International Society of Horticultural Science.


During the 1950’s especially, Professor Chapman rendered outstanding service to the Riverside campus during the development of the College of Letters and Science. Since there were relatively few senior faculty members in the new L&S College he and other senior members in Agricultural Sciences provided the vision and leadership needed in many Senate and non-Senate committees. During these early days as the campus developed Dr. Chapman served as chair of the campus Building and Development Committee, the campus and statewide Budget Committee, the Graduate Program Committee, the Committee on Arts and Lectures and many others.


Over the years Professor Chapman was active in the Riverside community. He supported the Mission Inn Foundation, Riverside Community Hospital Foundation, Riverside Symphony, Riverside Opera and was a member of the local Kiwanis Club for 65 years, serving as it president in 1952. He and Daisy established funds to support students in the sciences, music and performing arts. His interest in music came from his love of the piano and organ. He played by ear and earned much of his way through college by playing for parties and dances in Jazz Bands. Throughout his life he entertained friends and colleagues at home and in his many travels worldwide by playing their favorite tunes. At his 100th birthday celebration on campus Homer wowed the group by his rendition of “Stardust”.


Professor Chapman, a distinguished scientist, noted scholar with an international reputation has made lasting contributions to his University and has enriched the lives of colleagues and friends he has touched over more than seven decades. He will be missed but not forgotten.


A. L. Page

J. Letey

S. D. Van Gundy