Utilization of river silt in pre-modern China, its history and ecological significance

Abstract

As early as the 12^th century, Chinese farmers already started to intentionally scoop out river silt as fertilizer for agricultural production and apply river silt in farmland where fruit trees, mulberry trees and lowland rice were planted. After the 17^th century, lan heni 罱河泥 [scooping out river silt for fertilization] gradually became an important farming activity in Jiangnan [the southern part of the lower reaches of the Yangtze River], while river silt also turned into one of the four most essential types of fertilizers in the region. Lanni 罱泥, an alias of lan heni, was often carried out with the help of specialized farm implements, and in late fall, winter and spring or on rainy days so as to be staggered from other farming activities. Only after being sun-dried could the river silt scooped out be available for use. In the 1980s, along with the use of chemical fertilizers, river silt gradually lost its value as fertilizer, while lan heni was included in lists of intangible cultural heritage as an endangered folklore. In recent years, along with the continuous advancement of China’s ecological civilization, the traditional technique lan heni began to rejuvenate in some areas as it brings many co-benefits, such as improving aquatic ecosystem health. However, an important issue worth discussing is still how the role of river silt as fertilizer can be restored so that it can be used to improve the quality of the aquatic ecosystems.

Graphical abstract

Keywords

river silt / organic fertilizer / lan heni / intangible cultural heritage / ecological agriculture / soil erosion / planetary health

Highlight

	● By the 12th century, Chinese farmers were already extracting river silt for use as fertilizer, and after the 17th century, the technique known as lan heni became an important agricultural practice in Jiangnan.
	● The technique required specialized tools, was carried out seasonally to avoid conflicts with other farming tasks, and depended on sun-drying before the silt could be applied.
	● With the rise of chemical fertilizers in the 1980s, river-silt fertilization declined and lan heni came to be regarded as an endangered form of intangible cultural heritage.
	● Recently, ecological-civilization initiatives have supported a localized revival of lan heni , raising the question of how river silt can regain its role as a sustainable fertilizer.

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