Terrace farming in Chimi Lakhang, Bhutan. Photo Courtesy Anurag Tamhankar
Row Crop, Rice
North America, Europe, South Asia
Nitrogen, Phosphorus, Sediment
Terraces break long slopes into shorter ones, usually following the contour, creating a step-like landform. As water makes its way down a hill, terraces serve as small dams to intercept water and guide it to an outlet or pond it behind berms. There are four types of terraces - bench, channel, narrow, and broad based ridge - that reduce the length of slope on a hill side in order to reduce erosion and prevent gully formation and retain runoff. Bench terracing is done on relatively steep slopes and consists of excavating upper parts of the slope and filling the lower part with the soil materials from the upper parts. Channel terraces are wide, shallow channels that follow the land’s contour line. Narrow based terraces consist of a number of ridges spaced 1-2 meters apart across the slope; this type is especially found in high rainfall areas. Broad based ridge terraces are wide, low bunds following natural contour lines. Soil is excavated from both sides of the terrace; this type is especially found in low rainfall areas. 1
If the slopes are very irregular or if the soil is shallow (less than 6 inches), alternative practices should probably be used. In addition, terraces are generally designed to withstand up to 10-year storm events. Grass waterways are often used to collect water runoff from terrace edges.
Scalable to small farms?
1 "EU Database of Best Practices." Living Water Exchange: Promoting Replication of Good Practices for Nutrient Reduction and Joint Collaboration in Central and Eastern Europe. Web. Sept. 2013. http://nutrient2.iwlearn.org/nutrient-reduction-practices/eu-database-of-practices/view.; Wheaton, Rolland, and Edwin J. Monke. "Terracing as a "Best Management Practice" for Controlling Erosion and Protecting Water Quality." Agricultural Engineering Department. Purdue University, Cooperative Extension Service. Web. July 2014. https://www.extension.purdue.edu/extmedia/ae/ae-114.html.; Carman, Dennis. "Terraces." SERA-17, Minimizing Phosphorus Losses from Agriculture. Web. Jan. 2014. https://www.extension.purdue.edu/extmedia/ae/ae-114.html .