Xu Guangqi, as one of the pioneers of cultural exchange between China and the West, greatly promoted the development of modern science in China. He not only co-translated Euclid's Elements with Matteo Ricci but also oversaw the compilation of the Chongzhen Calendar, a work spanning over 130 volumes, and authored military texts such as Xu's Military Discourses and Questions on Military Affairs. His scientific achievements were multifaceted, yet the area where he devoted the most effort and achieved the greatest success was in agricultural and water conservancy research, with his most representative work being the renowned agricultural treatise Complete Treatise on Agriculture.
Xu Guangqi believed that agriculture was the foundation of everything, so he made full use of all his spare time by setting up experimental fields in places like Beijing, Tianjin, and Shanghai, where he personally conducted various agricultural technology experiments. The Complete Treatise on Agriculture was gradually compiled during his periods of leisure.
In the 35th year of the Wanli era (1607), Xu Guangqi returned to his hometown to observe mourning for his father, then opened up farmland there to conduct agricultural experiments. Over the next three years, he summarized many experiences in crop planting and farming, writing agricultural works such as "A Treatise on Sweet Potatoes," "Methods for Planting Cotton," and "Illustrated Guide to Bamboo Cultivation in Gardens." In the 41st year of the Wanli era (1613), Xu Guangqi resigned from his official post and went to Tianjin, where he continued agricultural experiments for five years. Three years later, he returned to Tianjin to carry out larger-scale agricultural experiments and wrote agricultural works like "Proposals for Land Reclamation" and "Miscellaneous Notes on Agricultural Heritage." These experiences of specializing in agricultural experiments and writing agricultural works allowed him to accumulate rich and valuable materials, laying a solid practical and theoretical foundation for his later compilation of the "Complete Treatise on Agriculture." In the 2nd year of the Tianqi era (1622), Xu Guangqi requested leave due to illness and returned home, but he still continued agricultural experiments and gathered and organized materials for writing the "Complete Treatise on Agriculture," hoping to pass down his lifelong efforts. By the 1st year of the Chongzhen era (1628), the "Complete Treatise on Agriculture" was largely completed; however, since Xu Guangqi had just been reinstated to his official position at that time and immediately began revising the calendar upon taking office, he had no time to attend to the final revisions of the "Complete Treatise on Agriculture." In the 6th year of the Chongzhen era (1633), Xu Guangqi passed away, and it was not until six years after his death that the "Complete Treatise on Agriculture" was finally revised, titled, and published by his disciple Chen Zilong and others.
The Complete Treatise on Agriculture consists of sixty volumes and twelve sections, totaling over five hundred thousand characters. With "agriculture as the foundation" as its guiding principle, it not only compiles agricultural techniques and policies summarized by previous generations but also incorporates the author's own scientific research results from agricultural and water conservancy practices. Its content covers agricultural fundamentals, land systems, farming operations, water conservancy, agricultural tools, tree cultivation, sericulture, planting, animal husbandry, manufacturing, and famine relief, aiming to promote adaptation to local conditions and full utilization of land resources to enrich the nation and benefit the people, fully meeting the needs of China as a vast agricultural country.
Among these, the section on famine relief occupies the foremost position in the entire book, spanning as many as eighteen volumes, which shows that Xu Guangqi placed great importance on preparing for famine and disaster relief. Although his starting point was to safeguard the interests of feudal rulers, these proposals also brought tangible benefits to the people. The "Famine Relief Herbal" and "Wild Vegetable Guide" included in the "Complete Treatise on Agriculture" served to benefit the populace in both lean and abundant years, possessing great practical value.
Xu Guangqi strongly advocated for developing northern agricultural production through land reclamation and water conservancy projects. Since the Wei and Jin dynasties, China had often made the north its political center, so the imperial court annually spent enormous sums on grain transport to move southern grain northward, placing a huge burden on state finances. To solve this problem, Xu Guangqi proposed using land reclamation, irrigation, and migration to develop northern agriculture, along with dry-farming techniques to boost southern crop yields, such as planting wheat to avoid waterlogging and rotating crops with broad beans. He also summarized the patterns of locust plagues and methods for controlling them.
Furthermore, Xu Guangqi conducted extensive research on the cultivation and promotion of cotton, which was primarily grown in the north, in the southeastern regions, and effectively proposed a fourteen-character yield-boosting formula: "carefully select seeds, sow early, plant deep with short stems, space sparsely and fertilize generously." According to statistics, the 159 cultivated plants recorded in the *Complete Treatise on Agriculture* were all sources of food, clothing, shelter, and transportation for the Chinese people over millennia, and their forms, characteristics, values, and cultivation methods were mostly reliable and well-evidenced, as Xu Guangqi compiled them by citing a wide range of historical documents with a cautious scientific attitude and conducting field investigations. Therefore, when reading the *Complete Treatise on Agriculture*, people can not only gain encyclopedic knowledge of ancient agriculture but also appreciate the rigorous and pragmatic approach of an ancient scientist.
The "Complete Treatise on Agriculture" essentially encompasses all aspects of ancient agricultural production and people's daily lives, while being permeated throughout with Xu Guangqi's agricultural governance philosophy of enriching the state and benefiting the people—a philosophy that distinguishes this work from other major agricultural texts, making it a seminal agricultural treatise on par with Jia Sixie's "Essential Techniques for the Common People" from the Northern Wei Dynasty.