UC Davis Cooperative Extension Vegetable Specialist
Tim joined the University of California in 1989 as an Extension Vegetable Specialist, briefly at UC Riverside before transferring to UC Davis. Dr. Hartz remained in that position until his retirement in 2017. In his 28 years as an Extension Specialist, Tim collaborated and supported UC farm advisors in all vegetable growing regions of the state. Tim’s work on a wide range of crops and issues was a classic example of the right person at the right time. His research program and close working relationships with farm advisors, crop advisers and growers facilitated the movement of the vegetable industry to an elevated level of understanding of nutrient and irrigation management.
Tim introduced the soil nitrate quick test to the state in the early 1990’s and developed this technique for both cool and warm season vegetable production systems. It facilitated an understanding of the value of residual soil nitrate and its importance to crop growth and yield. This concept now stands as a key practice used by the vegetable industry to improve nitrogen use efficiency. Initially many growers rejected this technique, but Tim knew that change was coming to the vegetable industry. He took short sabbaticals to Oregon in 2001 and to Florida in 2005 to study newly enacted water quality regulations and how they affected growers. He rightfully understood that California would follow suit. As a result, when the regional water quality control boards began enforcing the agricultural discharge waiver under the Porter-Cologne Act, Tim was able to help the California industry begin the long process of complying with the new sets of regulations impacting key vegetable production regions of the state, such as the Central Valley’s Region 5 and the Central Coast’s Region 3. Tim’s focus was helping growers comply by improving nutrient management efficiency with practical solutions.
Although Tim is probably best known for the soil nitrate quick test, his research program greatly improved our understanding of crop nutrient requirements for commercial vegetable production. Examples include nitrate mineralization in California soils, crop residue mineralization, mitigation of nitrate in tile drain water, nitrogen, phosphorus, potassium and calcium nutrition of vegetables including for organic production, yellow-shoulder disorder of processing tomatoes and irrigation management of vegetables, especially helping processing tomato growers make the transition from furrow to drip irrigation while balancing yield with fruit quality. All of these research projects have Tim’s distinctive fingerprint of keen insights leading to practical and economical solutions. Tim was patient with those who sought his counsel for their notion of management solutions to nutrient issues in California vegetables and always provided clear insight into the science and what was practical.
Tim was the mentor to a whole cohort of farm advisors, crop consultants, growers, and graduate students. He chaired the UC vegetable crops work group and was the UC liaison officer to the
California Melon Research Board. He was a key contact to advise agency and regulatory staff on issues of nutrient management and compliance with the water quality regulations and his patient guidance and clear explanations were greatly valued. He served on the board of the California Certified Crop Advisor program, helped revise the CCA exam and developed the training program for the CCA N management certification. Tim was the key speaker on nutrient management at over 500 grower meetings, trainings and field days, as well as at statewide and scientific conferences. He wrote numerous publications on nutrient and irrigation management that will serve as the basis of our understanding on these subjects for many years to come. We are fortunate that Tim summarized his substantial research in a forthcoming UCANR publication, “Efficient nutrient management in California Vegetable Production”. Everyone interested in nutrient management should have a copy of this book, as it provides a clear summary of the insights Tim brought to the area of nutrient management over his career.
In retirement Tim is active consulting with the South San Joaquin Valley Water Quality Coalition on their response to water quality regulatory challenges. He enjoys biking adventures with his wife, Marcia, and trying to remember how to play golf.