A career in chapters

As he neared the end of his Ph.D. at Virginia Tech, Jack interviewed for two University of Florida positions. The second, at the Range Cattle Agricultural Research and Education Center in Ona, Hardee County, was a small station in the middle of orange groves and cattle pastures, an hour's drive from Bradenton. Its laboratories were housed in converted mobile homes, furnished with wooden benches and basic equipment. The center had been founded in the late 1930s through the Hardee County Cattlemen's Association and became a unit of the University of Florida in 1941.

Center Director Findlay M. Pate interviewed him for a day — and on seeing his dark suit and new tie, told him to dress down for the field. A seminar for the Soil Science Department in Gainesville followed, and about a week later Pate called to offer him the job. Jack moved to Florida in November 1986.

His assignment was broad: research on the fertilization of grasses, legumes and field crops grown as forage for beef and dairy cattle in central and south Florida, working closely with agronomists and animal scientists at Ona and across IFAS. The core of the program was determining the fertilizer needs of tropical grasses and relating them to soil tests and plant tissue analysis, with secondary work on tropical legumes, white clover and symbiotic nitrogen fixation, carried out in field plots, greenhouses and small pastures grazed by cattle.

His early years at Ona produced a steady stream of publications and talks — at the American Society of Agronomy, the Soil and Crop Science Society of Florida, the International Conference on Livestock in the Tropics and, in 1989, the International Grassland Congress in Versailles, France, where he presented two papers.

Grants followed from the South Florida Water Management District, to develop pasture fertilization practices that minimize nutrient runoff; from Allied Fibers and Plastics, on nitrogen and sulfur fertilization of bahiagrass and the performance of grazing cattle; from the Florida Institute of Phosphate Research, on alfalfa grown on reclaimed soil; and from C.E.M. Corporation, on microwave digestion for plant tissue analysis. The funding let him hire laboratory assistants and a postdoctoral researcher and renovate his laboratory.

In 1990 the Graduate School expanded his role to Doctoral Research Faculty, allowing him to direct dissertations, and he received an Outstanding Achievement and Performance Award from the center. He applied for tenure a year earlier than customary. Tenure took effect on July 1, 1991, with promotion to associate professor on August 9, 1991.

As associate professor he expanded into chapters for major treatises and launched, with CRC Press, the Agriculture and Environment book series. Major grants included a USDA competitive grant to model the fate of nitrogen fertilizer and pesticides applied to bahiagrass, and two grants from the Florida Institute of Phosphate Research — $533,043 and then $593,751 — to study the effects of phosphogypsum on radon emissions, radioactivity and heavy metals in soil, water and forage.

His work became increasingly international, with invited presentations in Czechoslovakia (1992), Taiwan and the Philippines (1994), Australia (1993), and Venezuela and Brazil (1995). In September 1995 his center director and department chair began the process for his promotion; he became professor effective August 9, 1996.

His studies showed that established bahiagrass pastures gave no economic response to phosphorus and potassium fertilizer. Florida's recommendations were revised to drop P and K for established bahiagrass and to reduce its lime requirement — changes credited with saving the state's cattle producers millions of dollars in fertilizer costs. With South Florida Water Management District support, his team showed that phosphorus fertilization could be eliminated without reducing yield or quality while improving surface and ground water quality, because the grasses' deep roots draw on natural phosphorus in the spodic horizon. A $574,000 grant in 1998 extended the work to other grasses.

With roughly a million dollars from the Florida Institute of Phosphate Research, he evaluated phosphogypsum — a by-product of phosphate mining, stockpiled in Florida in quantities of more than 700 million tons — as a source of calcium and sulfur for crops. Pasture applications improved grass yield and quality, and radon at the soil surface could not be detected above background levels. Several countries that had dumped phosphogypsum at sea began using it as fertilizer.

Internationally, he helped the University of Nicaragua modernize its soil and plant tissue testing laboratory, advised Philippine officials on using industrial by-products to correct soil problems, built research ties with Taiwan and Brazil, and joined the board of the University of Cukurova Mediterranean International Center for Soils and Environmental Research in Turkey (1998). His visit to the Czech Republic led to a formal research and student exchange agreement between the Czech University of Agriculture in Prague and the University of Florida.

In 1999 he was one of eight faculty selected for the new University of Florida Research Foundation Professorship (1999–2001). The same year he received an honorary professorship from the Czech University of Agriculture at its May commencement, and on October 15 the University of Delaware presented him its Presidential Citation for Outstanding Achievement.

After serving on the Vice President's Advisory Committee, Jack was invited by Vice President for Agriculture and Natural Resources Michael V. Martin to move into administration. He became associate director of the Gulf Coast Research and Education Center at Bradenton and Dover on March 3, 2000, in a transitional role alongside interim director Ed Hanlon, with the understanding that he would become director after a year.

He ran the center's day-to-day operations while completing the LEAD IFAS program, the ESCOP/ACOP Leadership Development Program and, in June 2001, the Harvard Graduate School of Education's program for directors, chairs and deans. He reorganized the center into program management, farm operations, and human resource and fiscal groups; organized faculty into vegetable, ornamental and strawberry programs; created a competitive bonus program and seed funding for new faculty; started faculty and guest seminar series; and set up a center advisory committee and three commodity advisory committees with growers and industry.

He became director of the Gulf Coast REC on March 16, 2001, with plans to modernize the 1965 Bradenton building, expand distance learning and the new Doctor of Plant Medicine program, and find alternatives to the fumigant methyl bromide. Within months, state budget shortfalls led UF/IFAS to announce in November 2001 that the Bradenton center would close.

Growers, elected officials and staff filled a public meeting at the center on November 15, 2001. A task force of growers and industry leaders formed to save it, and Jack worked between the university administration and the agricultural community. The legislature protected the center from that year's cuts and redirected unspent funds toward planning, land and construction for a new regional center.

Hillsborough and Manatee counties both offered sites. In August 2002 UF/IFAS selected Hillsborough County's offer of about 475 acres at Balm, and Jack led planning for the new state-of-the-art facility that became today's Gulf Coast Research and Education Center.

The new Gulf Coast Research and Education Center opened at Balm in 2005. At its dedication, growers Jay Taylor and Tony DiMare asked Jack and UF/IFAS Senior Vice President Jimmy Cheek to consider a new kind of event: a partnership between Florida's agricultural industries and IFAS, with vendor, university, government and nonprofit booths, educational programs where growers could earn continuing-education credits, and field tours of the latest research.

The first Florida Ag Expo took place on December 8–9, 2006, organized with a committee of growers, industry representatives and UF faculty, and with partners including the Florida Fruit & Vegetable Association, Florida Grower magazine, the Florida Strawberry Growers Association and the Florida Tomato Committee. Jack opened the program; Agriculture Commissioner Charles Bronson gave the keynote, and a HUD-funded prototype house for migrant farm workers, designed to withstand fire and hurricanes, was unveiled at the center.

More than 800 people attended — filling the conference room and far exceeding the turnout for the center's opening — and more than 60 exhibitors took part. Senior Vice President Cheek credited Jack's foresight and initiative, noting that university leaders, initially unconvinced, now wanted the Expo held every year. It has been held annually since.

On May 12, 2020, he took on a second center, becoming interim director of the UF/IFAS Fort Lauderdale Research and Education Center in Davie while continuing to lead the Gulf Coast REC. UF/IFAS now lists him as Center Director and Professor of Soil and Water Science at both centers.

At the Gulf Coast REC he has led planning for the Center for Applied Artificial Intelligence in Agriculture, together with associate director Nathan Boyd. Scientists at the hub will work with researchers across UF/IFAS and industry to breed plants that resist pests and disease, help growers use fewer chemicals, and design and build robotic technologies in a dedicated research shop. He estimates the center will directly employ about 100 people, from computer scientists and engineers to AI specialists and graduate students.

After five years of planning, UF officials broke ground on the center on November 7, 2025, during the Gulf Coast REC's 100th-anniversary celebration.