Conservation tillage practices

Tillage is the preparation of land to grow crops, which involves digging, stirring, and overturning soil. Conservation tillage is any method of soil cultivation that keeps at least one-third of cultivated soil covered with the previous year’s crop residue. There are several types of reduced or low-intensity tillage, including mulch till, ridge till, strip till, and no-till; under no-till farming the soil is not tilled at all. Conservation tillage is often used with crop rotations, composting, and other soil erosion control practices. Tillage practices affect soil carbon and water pollution, as well as farmers’ energy and fertilizer use (USDA-Horowitz 2010, MN BWSR-Conservation tillage).

Expected Beneficial Outcomes (Rated)

  • Reduced soil erosion

  • Improved soil quality

Other Potential Beneficial Outcomes

  • Reduced run-off

  • Improved water quality

  • Reduced emissions

Evidence of Effectiveness

There is strong evidence that conservation tillage practices reduce soil erosion and improve soil quality and structure, especially in the soil’s top surface layer (Manley 2005*, Willekens 2014*, Moreno 2006*, Roldan 2005*, Melero 2009*, Madejon 2009*, Madejon 2007*, Zhang 2007*). Improving soil quality and structure increases water penetration and soil’s moisture content and reduces run-off (MN BWSR-Conservation tillage, Zhang 2007*). Agricultural run-off can carry excess nutrients, sediment, pesticides, and other pollutants that contaminate surface water and groundwater (USDA-NRCS Water). 

Conservation tillage reduces both run-off and soil erosion, though it may be more effective at reducing erosion than run-off (Armand 2009*). Reductions in soil erosion increase substantially with increasing scale (Leys 2010*). Conservation tillage can also increase profitability and reduce farm operating costs, since fewer tillage trips reduce fuel use, labor costs, and machinery repair costs (Knowler 2007*USDA-NRCS Boyle 2006). By reducing fuel use, conservation tillage also reduces emissions (USDA-NRCS 2012, Alvarez 2005*).

Conservation tillage practices, especially no-till farming, may be an effective means of carbon sequestration, although studies show variation in the amount of stored carbon by region, crop (Manley 2005*), and depth (Bauer 2006*, Melero 2009*, Alvarez 2005*). 

Impact on Disparities

No impact on disparities likely

Implementation Examples

According to the 2012 Census of Agriculture, US farmers used no-till practices on 96.5 million acres, conservation tillage on 76.6 million acres, and conventional tillage on 105.7 million acres. Kansas, Nebraska, North Dakota, South Dakota, Iowa, and Montana are the top states in no-till practices by millions of acres, and Iowa, Illinois, North Dakota, Minnesota, and Kansas are the top states in conservation tillage by millions of acres (USDA-Ag census 2012).

Some states (e.g., Minnesota) have established resources to support conservation tillage practices (MN BWSR-Conservation tillage). In other states (e.g., Pennsylvania and Colorado) producers have formed a network to share ideas and experiences to support no-till farming (PA No-till, CO No-till). 

The American Farmland Trust (AFT) is a national organization that helps farmers improve conservation efforts. AFT also runs the BMP challenge guaranteeing against any potential income loss for farmers who reduce fertilizer use or use conservation tillage practices (AFT).

Implementation Resources

USDA-NAL Conservation tillage - US Department of Agriculture (USDA), National Agricultural Library (NAL). Soil and water management: Conservation tillage practices and erosion control.

MU Ext-No-till planting manual - University of Missouri Extension (MU Ext). Missouri no-till planting systems manual. M164;1997.

USDA-Ag census by state - US Department of Agriculture (USDA). 2012 Census of agriculture publications: Census by state.

Citations - Evidence

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Manley 2005* - Manley J, van Kooten GC, Moeltner K, Johnson DW. Creating carbon offsets in agriculture through no-till cultivation: A meta-analysis of costs and carbon benefits. Climatic Change. 2005;68(1-2):41–65.

Willekens 2014* - Willekens K, Vandecasteele B, Buchan D, De Neve S. Soil quality is positively affected by reduced tillage and compost in an intensive vegetable cropping system. Applied Soil Ecology. 2014;82:61-71.

Moreno 2006* - Moreno F, Murillo J, Pelegrín F, Girón I. Long-term impact of conservation tillage on stratification ratio of soil organic carbon and loss of total and active CaCO3. Soil and Tillage Research. 2006;85(1-2):86-93.

Roldan 2005* - Roldán A, Salinas-García JR, Alguacil MM, Caravaca F. Changes in soil enzyme activity, fertility, aggregation and C sequestration mediated by conservation tillage practices and water regime in a maize field. Applied Soil Ecology. 2005;30(1):11-20.

Melero 2009* - Melero S, López-Garrido R, Murillo JM, Moreno F. Conservation tillage: Short- and long-term effects on soil carbon fractions and enzymatic activities under Mediterranean conditions. Soil and Tillage Research. 2009;104(2):292-298.

Madejon 2009* - Madejón E, Murillo JM, Moreno F, et al. Effect of long-term conservation tillage on soil biochemical properties in Mediterranean Spanish areas. Soil and Tillage Research. 2009;105(1):55-62.

Madejon 2007* - Madejon E, Moreno F, Murillo JM, Pelegrin F. Soil biochemical response to long-term conservation tillage under semi-arid Mediterranean conditions. Soil and Tillage Research. 2007;94(2):346-352.

Zhang 2007* - Zhang GS, Chan KY, Oates A, Heenan DP, Huang GB. Relationship between soil structure and runoff/soil loss after 24 years of conservation tillage. Soil and Tillage Research. 2007;92(1-2):122-128.

MN BWSR-Conservation tillage - Minnesota Board of Water and Soil Resources (MN BWSR). Carbon sequestration: Conservation tillage and cover crops.

USDA-NRCS Water - US Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS). Water.

Armand 2009* - Armand R, Bockstaller C, Auzet AV, Vandijk P. Runoff generation related to intra-field soil surface characteristics variability: Application to conservation tillage context. Soil and Tillage Research. 2009;102(1):27-37.

Leys 2010* - Leys A, Govers G, Gillijns K, Berckmoes E, Takken I. Scale effects on runoff and erosion losses from arable land under conservation and conventional tillage: The role of residue cover. Journal of Hydrology. 2010;390 3-4):143-154.

Knowler 2007* - Knowler D, Bradshaw B. Farmers' adoption of conservation agriculture: A review and synthesis of recent research.  Food Policy. 2007; 32(1):25-48.

USDA-NRCS Boyle 2006 - Boyle, K. The economics of on-site conservation tillage. US Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS); 2006.

USDA-NRCS 2012 - US Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS), US Environmental Protection Agency (US EPA). Agricultural air quality conservation measures: Reference guide for cropping systems and general land management. 2012.

Alvarez 2005* - Alvarez R. A review of nitrogen fertilizer and conservation tillage effects on soil organic carbon storage. Soil Use and Management. 2005;21(1):38–52.

Bauer 2006* - Bauer PJ, Frederick JR, Novak JM, Hunt PG. Soil CO2 flux from a norfolk loamy sand after 25 years of conventional and conservation tillage. Soil and Tillage Research. 2006;90(1-2):205–11.

Citations - Implementation Examples

* Journal subscription may be required for access.

USDA-Ag census 2012 - US Department of Agriculture (USDA). 2012 Census of agriculture highlights: Conservation: Producers protect or improve millions of acres of agricultural land. 2014.

MN BWSR-Conservation tillage - Minnesota Board of Water and Soil Resources (MN BWSR). Carbon sequestration: Conservation tillage and cover crops.

PA No-till - Pennsylvania No-Till Alliance. Farmers improving soil health.

CO No-till - Colorado Conservation Tillage Association. Serving the conservation and no-till farmers of the High Plains.

AFT - American Farmland Trust (AFT). Agricultural conservation innovation center.

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