Note on green fertiliser in ancient China

凡美田之法，緑豆爲上，小豆、胡麻次之。悉皆五、六月中䆊種，七月、八月犂䅖殺之，爲春穀田，則畝收十石，其美與蠶矢、熟糞同。

Regarding methods for fertilising the fields, mung beans are the best, followed by azuki beans and sesame. All of them are to be sown during the fifth and sixth months and killed by ploughing during the seventh and eighth months. Preparing cereal fields for [the coming] spring this way yields ten dan per mu. The benefits compare with those of silkworm droppings and ripe manure.[2]

* From Jia Sixie 賈思勰 (fl. 530–544), Qimin yaoshu yizhu 齊民要術譯注 (Shanghai: Shanghai guji chubanshe, 2000), 34.

[1] The unit of land measurement mu was in theory equivalent to 240 square double-paces (bu 步) from the Warring States period but varied in practice according to period. One mu in Jia Sixie’s days roughly corresponds to one fifth to one sixth of an acre, approximately 675 to 810 square metres. The unit of weight measurement dan also varied according to region in his days, and a dan where he lived (Northern Wei territory) was roughly 53 kg.

[2] This is the earliest known account of Chinese use of leguminous plants as green fertiliser (a practice already well-known to the Greeks); see Francesca Bray, Science and Civilisation in China. Vol. 6, Biology and Biological Technology. Part II: Agriculture (Cambridge University Press, 1984), 293. An earlier allusion to using weed as green fertiliser can be found in the poem “Liangsi” 良耜 (Sharp ploughshares) in the Shijing.

Hanging scroll by Qi Baishi 齊白石 (1864-1957)

Image credit: National Palace Museum, Taipei

民國齊白石豆莢蚱蜢　軸。國立故宮博物院，台北，CC BY 4.0 @ www.npm.gov.tw