Yelao 野老 or Yelaoshu 野老書 "Book of the old man in the fields", also called Yelao 野老 "The old man in the fields", was a book on agriculture written by an unknown author of the late Zhou period 周 (11th cent.-221 BCE). The interpretation of the title follows the explanation by the Later Han-period 後漢 (25-220 CE) scholar Ying Shao 應劭 (d. c. 203 CE). A fragment of Yuan Shu's 袁淑 text Zhenyinzhuan 真隱傳 (quoted in the Wang Yinglin's 王應麟 critical essay Hanshu yiwen kaozheng 漢書藝文考證 from the Song period 宋) sas that the author lived in the regions of Qin 秦 (modern Shaanxi) or Chu 楚 (modern Hubei).
The imperial bibliography Yiwen zhi 藝文志 in the official dynastic history Hanshu 漢書 lists the book Yelao with a length of 17 chapters. The Qing-period 清 (1644-1911) scholar Ma Guohan 馬國翰 (1794-1857) followed a statement in Ma Su's 馬驌 (1621-1673) history book Yishi 繹史 from the early Qing period where the Qin-period 秦 (221-206 BCE) Counsellor-in-chief Lü Buwei 呂不韋 (d. 253 BCE) is seen as the father of agriculture. Ma Guohan therefore extracted some statements on agriculture in the chapter Ronglun 容論 of the book Lüshi chunqiu 呂氏春秋 (sections Shangnong 上農, Rendi 任地, Biantu 辨土, and Shenshi 審時) that Ma identified as fragments of the book Yelao. The result is to be found in his series Yuhanshanfang jiyi shu 玉函山房輯佚書.
The part Shangnong is a general stress on the importance of agriculture. The other sections describe methods of farming, soil amelioration and irrigation, as well as various tools and crops. The xitianfa 畦種法 (field compartment) method seems to have been the precursor of the qutianfa 區種法 described, for instance, in Fan Shengzhi's 氾勝之 agricultural treatise from the Han period.