Prior to the 1980s, Tai Lake Region farmers made a compost out of local materials for use as basal fertilizer for paddy rice. This "waterlogged compost" is known locally as "oufei" or "caotangni" and was developed before the Song Dynasty (960 AD). In winter, farmers harvested sediments from canals and ponds using a scoop, piling them on the banks. In April, these were mixed in a pit with Chinese milk vetch (a legume green manure), rice straw, and manures (water buffalo, pig, goat, silkworm), and filled with water. The mix was then fermented anaerobically until removed from the pit in mid-June and applied to rice paddy fields immediately prior to plowing, flooding and puddling. 

Use of oufei compost has sustained rice yields averaging 4 tonnes/hectare for centuries. By composting under anaerobic conditions, organic matter is reduced to ammonium, the ideal fertilizer for paddy rice, so that nutrients are made available to rice throughout the cropping season. Though making oufei compost was considered essential for rice production into the 1960s, the method has virtually disappeared in all wealthy areas of China. As a result, Tai Lake Region canals and waterways have filled with sediments, causing problems with transportation, irrigation and flood control. The disappearance of oufei results from development of a cheap replacement- chemical fertilizers, and because it requires copious amounts of strenuous labor. To make oufei compost a part of future farming systems, improving soil quality and preventing sediment accretion in canals, it must be reinvented as a mechanized technology supported by clear economic and/or policy incentives. 

Use Renewable Resources

Use of the legume green manure, Chinese milk vetch, in composts makes use of biological nitrogen fixation. Sediments, green manure and straw are naturally-occurring, renewable, on-farm inputs.

Conserve Resources

Using sediments conserves soil by returning soils lost from fields by erosion, a process of "reverse erosion".

Manage Ecological Relationships

Nutrient cycling is increased by composting and returning crop residues and manures to soils.

Adjust to Local Environments

Anaerobic composting makes fertilizers available under the anaerobic conditions in flooded paddy fields.

Manage Whole Systems

By harvesting sediments, aquatic systems are kept clear of sediment accretion while maintaining fertility in paddy land, managing nutrients across village landscapes.

Maximize Long-Term Benefits

Use of sediments and organic fertilizer builds soil fertility over the long term. 

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King, F.H. 1911. Farmers of Forty Centuries, or Permanent Agriculture in China, Korea and Japan. Mrs. F. H. King, Madison, Wisconsin, USA.

Ellis, E.C., and S.M. Wang. 1997. Sustainable traditional agriculture in the Tai Lake Region of China. Agriculture Ecosystems & Environment 61:177-193.

Cheng, L.L., and Q.X. Wen. 1997. Transformation and managment of manure nitrogen. Pages 281-302 in: Z.L. Zhu, Q.X. Wen and J.R. Freney, editors. Nitrogen in Soils of China, Developments in Plant and Soil Sciences 74. Kluwer Academic Publishers, Dordrecht, The Netherlands.