Zaishi 宰氏 or Zaishi shu 宰氏書 "The book of Master Zai" was an agricultural treatise of early China. The identity of Master Zai cannot be substantiated, neither can the date of compilation be determined. Ma Zong 馬總 (d. 823), author of the Tang-period 唐 (618-907) encyclopaedia Yilin 意林, assumed that Master Zai was identical to Jiran 計然, better known as the philosopher Wenzi 文子, who had the family name Xin 辛 - a character easily confounded with Zai 宰.
During the Northern Song period, Zheng Qiao 鄭樵 (1104-1162), author of the history book Tongzhi 通志 and the genealogical chapter in it, Shizu lüe 氏族略, confirmed this assumption. The Qing-period 清 (1644-1911) collector Ma Guohan 馬國翰 (1794-1857) likewise backed this hypothesis, and equated the book Zaishi shu with the collection Fanzi Jiran 范子計然. It is found in Ma's series Yuhan shanfang jiyi shu 玉函山房輯佚書中, a collection of fragments.