Zenong yaolu 澤農要錄 a book on rice cultivation in north China written by Wu Bangqing 吳邦慶 (1768-1848), courtesy name Jifeng 霽峰, from Bazhou 霸州, Zhili (today's Hebei). His highest office was Director of the Grand Canal in Hedong (Hedong hedao zongdu 河東河道總督).
Wu's motivation to write this book was to spread the knowledge of rice cultivation of south China to the Yellow River plain. The Zenong yaolu consists of 6 juan divided into ten chapters on farming with the seasons (Shoushi 授時), field allotment (Tianzhi 田制), seed classification (Bianzhong 辨種), land clearance and ploughing (Gengken 耕墾), planting and replanting (Shuyi 樹藝), weeding and sowing (Yunzi 耘籽), preparing the soil (Peiyong 培壅), irrigation (Guangai 灌溉), use of water (Yongshui 用水), and harvesting (Shouhuo 收獲).
In the book, the complete process of rice production from land reclamation to farming, seed selection, sowing, fertilization, irrigation, harvesting, and storage is described. The text is, in a traditional way, mainly composed of quotations about rice production as found in ancient books, yet the author adds his private recommendations and conclusions in front of each chapter. The author points out that the North China Plain was rich in water resources, which only had to be made use of consequently to implement southern types of rice fields (like embanked fields xxx 圍田, “chest fields” 柜田, seashore fields 涂田, terraced fields 梯田, “frame fields” 架田 or “sand fields” 沙田) in the north.
Wu constated that local gazetteers of north China used a immense amount of names and designations for dry rice and even for wet rice since hundreds of years. It was therefore necessary to revive irrigation projects to expand the cultivation of wet rice. However, because of local conditions, it was necessary in the dry lands of north China to rotate crops such as wet rice and maize, if not cultivating dry rice over several years. The book emphasizes that farmers cultivating wet rice should pay attention to the preparation of fields, manure, seeds, and irrigation methods. He also put forward the idea to implement hydraulic projects in a reasonable way by taking into consideration the conditions of the terrain, the water potential, methods to remove obstacles or size and urgency of he project.