The Hat Sai Yai Farm, Hua Hin District, Prachuap Khiri Khan Province, began operations in the year B.E. 2508 (A.D. 1965) on a plot of His Majesty the King's own land, which he had graciously commanded to be established as an experimental farm so that various means of raising of livestock and poultry and the growing of cash crops on arid and sandy soil could be tried out.

During the earlier years of operations, cultivated many varieties of tamarind and cashew-nut trees in order to study the relationship between moisture of the soil and the required amount of fertilizers. Later on, kitchen garden crops and field plants, such as pineapples, corn and mulberry bushes were grown in demonstration plots as example to farmers for cultivation in similarly arid and sandy soil.