252:. At one end of a contour the slope of the land will always be steeper than at the other. Thus when plowing parallel runs paralleling any contour the plow furrows soon deviate from a true contour. Rain water in these furrows will thus flow sideways along the falling "contour" line. This can often concentrate water in a ways that exacerbates erosion instead of reducing it. Yeomans was the first to appreciate the significance of this phenomenon. Keyline cultivation utilizes this "off contour" drift in cultivating furrows to control the movement of rain water for the benefit of the land. ( See Chapter 7 in
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238:. The proper combination of such farming methods can be determined by various climatic and soil conditions of that given area. Farming sites are often classified into five levels: insensitive, mild, moderate, high and extreme, depending on the regions soil sensitivity. Contour farming is applied in certain European countries such as Belgium, Italy, Greece, Romania, Slovenia and Spain in areas with higher than 10% slope.
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120:. These contour lines create a water break which reduces the formation of rills and gullies during times of heavy precipitation, allowing more time for the water to settle into the soil. In contour plowing, the ruts made by the plow run perpendicular rather than parallel to the slopes, generally furrows that curve around the land and are level. This method is also known for preventing tillage erosion.
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intensive under most circumstances. Reducing fertilizer loss not only saves the farmer time and money, but it also decreases risk of harming regional freshwater systems. Soil erosion caused from heavy rain can encourage the development of rills and gullies which carry excess nutrients into freshwater systems through the process of
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Demonstrations showed that contour farming, under ideal conditions, will increase yields of row crops by up to 50%, with increases of between 5 and 10% being common. Importantly, the technique also significantly reduces soil erosion, fertilizer loss, and overall makes farming less energy and resource
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Phoenicians ... practiced some of the earliest forms of contour farming ...(and)... helped spread contour farming throughout the
Mediterranean ... however, the Romans ... preferred straight furrows. Over a period, societies who embraced irrigation farming adopted this method of plowing and
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Approximately 35 million acres of formerly cultivated land have essentially been destroyed for crop production. . . . 100 million acres now in crops have lost all or most of the topsoil; 125 million acres of land now in crops are rapidly losing
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Soil erosion prevention practices such as this can drastically decrease negative effects associated with soil erosion such as reduced crop productivity, worsened water quality, lower effective reservoir water levels, flooding, and
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where stones are placed around the contours of slopes. Contour ploughing has been proved to reduce fertilizer loss, power and time consumption, and wear on machines, as well as to increase crop yields and reduces soil erosion.
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The practice is effective only on slopes with between 2% and 10% gradient and when rainfall does not exceed a certain amount within a certain period. On steeper slopes and areas with greater rainfall, a procedure known as
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Zhang, Ronghua; Liu, Xia; Heathman, Gary C.; Yao, Xiaoyou; Hu, Xuli; Zhang, Guangcan (2013). "Assessment of soil erosion sensitivity and analysis of sensitivity factors in the
Tongbai–Dabie mountainous area of China".
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Xu, Lifen; Xu, Xuegong; Meng, Xiangwei (2013). "Risk assessment of soil erosion in different rainfall scenarios by RUSLE model coupled with
Information Diffusion Model: A case study of Bohai Rim, China".
309:"Contour Farming for Cropland in the Pacific." University of Hawai‘i - College of Tropical Agriculture and Human Resources. Ed. University of Hawaii at Manoa. USDA NRCS Practice (330), Web. <
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to promote the method to farmers. By 1938, the introduction of new agricultural techniques such as contour plowing had reduced the loss of soil by 65% despite the continuation of the drought.
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Penn State
College of Agricultural Sciences. "Tillage Erosion." Agronomy Guide (Penn State Extension). Penn State College of Agricultural Sciences, 2013. <
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is used with contour farming to provide additional protection. Contour farming is most effective when used with other soil conservation methods like
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which can permanently transform a formerly productive landscape to an arid one that becomes increasingly intensive and expensive to farm.
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Reinhardt, Claudia, and Bill Ganzel. "Contour
Plowing & Terraces during the 1930s Depression." Living History Farm., 2003. Web. <
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The Soil
Conservation Service worked with state governments and universities with established agriculture programs such as the
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system is critical of traditional contour plowing techniques, and improves the system through observing normal land form and
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Panagos, Panos; Borrelli, Pasquale; Meusburger, Katrin; Zanden, Emma H. van der; Poesen, Jean; Alewell, Christine (2015).
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Hasholt, Bent; et al. (1997). "Sediment delivery to streams from adjacent slopes on agricultural land in
Denmark".
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589:"Modelling the effect of support practices (P-factor) on the reduction of soil erosion by water at European scale"
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Contour plowing is also promoted in countries with similar rainfall patterns to the United States such as western
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Hogan, Michael C., and GreenFacts. "Desertification." Encyclopedia of Earth., 22 July 2010. Web. <
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157:. However, the Romans preferred cultivation in straight furrows and this practice became standard.
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erosion is the soil movement and erosion by tilling a given plot of land. A similar practice is
415:"Organic Farming for Crop Improvement and Sustainable Agriculture in the Era of Climate Change"
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This was one of the main procedures promoted by the US Soil
Conservation Service (the current
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481:"Contour Farming." Encyclopædia Britannica. Ed. Encyclopædia Britannica., 2013. Web. <
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IAHS Publications-Series of
Proceedings and Reports-Intern Assoc Hydrological Sciences
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http://www.ctahr.hawaii.edu/wq/publications/Final_FactSheets/ContourFarmingCrop330.pdf
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The extent of the problem was such that the 1934 "Yearbook of
Agriculture" noted that
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first developed the practice of contour farming and spread it throughout the
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when it became apparent that soil erosion was a huge problem along with
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Looking after our land - Soil and Water Conservation in Dryland Africa
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Van Oost, K. K.; Govers, G. G.; de Alba, S. S.; Quine, T. A. (2006).
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678:(2002) Africans go back to the land as plants reclaim the desert,
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Natural Resources Conservation Service page on sustainable farming
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http://www.britannica.com/EBchecked/topic/135192/contour-farming
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http://www.livinghistoryfarm.org/farminginthe30s/crops_11.html
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History of Twentieth Century Soil Conservation and Keyline.)
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established the Soil Conservation Service in 1935 during the
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515:"NRCS Conservation Practice Standard 330-Contour Farming"
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NRCS Conservation Practice Standard 330-Contour Farming
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and/or planting across a slope following its elevation
688:- Detailed instructions for contour bund construction.
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Roychoowdhury, Banerjee U; Sofkova, S; Yah, J (2013).
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http://extension.psu.edu/agronomy-guide/cm/sec1/sec11e
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137:. Contour farming is considered an active form of
671:Priority One. Together We Can Beat Global Warming
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651:Encyclopædia Britannica page on contour farming
692:BBC News - Sahara desert frontiers turn green
656:Purdue University article on contour farming
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470:http://www.eoearth.org/view/article/151708/
259:Contour bunding has been widely adopted in
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69:Learn how and when to remove this message
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32:This article includes a list of general
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446:Owuor Otieno, Mark (18 February 2018).
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167:Natural Resources Conservation Service
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448:"What Is Contour Farming"
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281:George Washington Carver
169:) during the 1930s. The
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