Kleberg began ranching in 1916, at his father's King Ranch. He succeeded his father as ranch manager in 1932, following his death, and in 1935, became president of King Ranch when it began operating as a family corporation. which included land in the states of Florida,
Kentucky, and
Pennsylvania, as well as the countries of Argentina, Australia, Brazil,
Morocco, Spain, and
Venezuela; he also owned land in Cuba, which was seized after the
communist government took power in 1960. The land expansions of Kleberg made King Ranch the largest
citrus grower in the United States, due to 36,000 acres of citrus groves in Florida, as well as one of the ten largest
sugarcane grower in the United States. He also continued his father's effort to expand King Ranch's land usage beyond agriculture, with him creating an oil lease with
Humble Oil, which was the largest one ever issued for private land. He also headed King Ranch's transition into leasing its land for hunting. Besides ranching, he had a footing in banking, lumber, and newspapers. Between 1918 and 1940 the ranch developed the Santa Gertrudis breed of cattle by
cross-breeding cattle of mostly
Indian (
zebuine) breeding with European (
taurine)
Shorthorn stock. He is credited with having invented the
cattle prod around 1930, though other versions date to 1917. He also invented the
root plow and bred
grazing grass, as well as helping to stop the spread of
babesiosis. In 1947, he appeared on the cover of
Time. Kleberg also bred
Quarter Horse and
Thoroughbred racehorses. Trained by
William J. Hirsch, his horses including
Assault,
Middleground, and
Bold Venture. He also purchased
Canonero II for $1,000,000. == Personal life and death ==