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United States Department of Agriculture

Agricultural Research Service

Research Project: INTERACTIONS BETWEEN LAND USE, LAND MGMT, AND CLIMATE CHANGE: RELATIONS TO CARBON AND NITROGEN CYCLING, TRACE GASES AND AGROECOSYSTEMS

Location: Soil Plant Nutrient Research (SPNR)

Title: US agriculture’s relationship to soil carbon

Author
item Follett, Ronald

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 26, 2009
Publication Date: November 1, 2009
Citation: Follett, R.F. 2009. US agriculture’s relationship to soil carbon. Journal of Soil and Water Conservation. Vol. 64, No. 6 159A-165A.

Interpretive Summary: Concerns of Hugh Hammond Bennett and others led to the formation of the Soil Erosion Service, created within the USDA in 1935 was the precursor to the Soil Conservation Service. Provided here is a historic perspective of the use of US agricultural lands and soil C, compare amounts of soil organic carbon (SOC) in cropland vs. land that has never been cultivated (native), and consider the future role of SOC in US agricultural lands. Within this context, the protection of SOC will continue to be a necessary component to the economic and environmental health of US agriculture. Little doubt exists that among the great negative impacts was severe loss of SOC associated with the eroding soil. There is a linear decline in SOC content with accumulative soil erosion and the enrichment ratio is about 3-to 5. Accelerated erosion in the US began with European settlement more that four centuries ago. Following the end of the Civil War in 1865, westward population movement and population growth was increasingly dynamic. Movement of the US population was aided by the Homestead Act of 1862 and completion of the transcontinental railroad in 1869. From the 1870’s until about 1940 grain produced per unit of land area in the US was static. Thus, along with the westward movement and growing populations, increasing areas of land were broken from their native condition. The ‘Dust Bowl’ of the 1930’s provided a hard lesson about the use of large-scale, improper soil management that, coupled with drought had devastating effects upon a nation and society. By 1940 over 2.5 million people had moved out of the Great Plains. Following the shock of the 1930’s ‘Dust Bowl’, and after 1940, better land and resource management began to result, and though not directly recognized at the time – better soil C management, helped restore productivity to the land and the quality of the water and to conserve and help restore what were no doubt previous major losses of SOC. Land under the ‘Soil Bank Act’ of 1956 was set aside primarily to divert cropland from the production of major crops and thus to decrease agricultural inventories but with a second purpose of establishing protective vegetative cover on land that needed conservation practices and protection from wind and water erosion. Major subsequent technological innovations included: (a) ‘Mechanization’ wherein farms used gasoline tractors. There was increased use and availability of specialized agricultural machinery, including combines, planting equipment, high-clearance tillage equipment, center-pivot irrigation rigs, and other equipment. (b) ‘Crop varieties’ were improved with genetic advances and introduction of new crops (e.g. soybean) to push farmers towards ‘monocultures’, limited rotations, and increased ‘crop specific’ knowledge by farmers so that optimized yields could be obtained, and (c) ‘Agricultural chemical’ use such as manufactured nitrogen (N) fertilizer and use of agricultural pesticides increased after WWII. These three technologies led farmers to increasingly grow a single or only a few crops and to develop increased confidence that, with the use of technology, their crops would flourish. (d) Coupled with the above is a fourth technology that is referred to as ‘improved soil management’ (reduced tillage, enhanced crop residue management, water and precipitation conservation, and plant nutrient management). Improved soil management also includes use of crop rotations and cover crops. These management components are instrumental to decreasing soil erosion and protecting and restoring SOC.

Technical Abstract: Concerns of Hugh Hammond Bennett and others led to the formation of the Soil Erosion Service, created within the USDA in 1935 was the precursor to the Soil Conservation Service. Provided here is a historic perspective of the use of US agricultural lands and soil C, compare amounts of soil organic carbon (SOC) in cropland vs. land that has never been cultivated (native), and consider the future role of SOC in US agricultural lands. Within this context, the protection of SOC will continue to be a necessary component to the economic and environmental health of US agriculture. Little doubt exists that among the great negative impacts was severe loss of SOC associated with the eroding soil. There is a linear decline in SOC content with accumulative soil erosion and the enrichment ratio is about 3-to 5. Accelerated erosion in the US began with European settlement more that four centuries ago. Following the end of the Civil War in 1865, westward population movement and population growth was increasingly dynamic. Movement of the US population was aided by the Homestead Act of 1862 and completion of the transcontinental railroad in 1869. From the 1870’s until about 1940 grain produced per unit of land area in the US was static. Thus, along with the westward movement and growing populations, increasing areas of land were broken from their native condition. The ‘Dust Bowl’ of the 1930’s provided a hard lesson about the use of large-scale, improper soil management that, coupled with drought had devastating effects upon a nation and society. By 1940 over 2.5 million people had moved out of the Great Plains. Following the shock of the 1930’s ‘Dust Bowl’, and after 1940, better land and resource management began to result, and though not directly recognized at the time – better soil C management, helped restore productivity to the land and the quality of the water and to conserve and help restore what were no doubt previous major losses of SOC. Land under the ‘Soil Bank Act’ of 1956 was set aside primarily to divert cropland from the production of major crops and thus to decrease agricultural inventories but with a second purpose of establishing protective vegetative cover on land that needed conservation practices and protection from wind and water erosion. Major subsequent technological innovations included: (a) ‘Mechanization’ wherein farms used gasoline tractors. There was increased use and availability of specialized agricultural machinery, including combines, planting equipment, high-clearance tillage equipment, center-pivot irrigation rigs, and other equipment. (b) ‘Crop varieties’ were improved with genetic advances and introduction of new crops (e.g. soybean) to push farmers towards ‘monocultures’, limited rotations, and increased ‘crop specific’ knowledge by farmers so that optimized yields could be obtained, and (c) ‘Agricultural chemical’ use such as manufactured nitrogen (N) fertilizer and use of agricultural pesticides increased after WWII. These three technologies led farmers to increasingly grow a single or only a few crops and to develop increased confidence that, with the use of technology, their crops would flourish. (d) Coupled with the above is a fourth technology that is referred to as ‘improved soil management’ (reduced tillage, enhanced crop residue management, water and precipitation conservation, and plant nutrient management). Improved soil management also includes use of crop rotations and cover crops. These management components are instrumental to decreasing soil erosion and protecting and restoring SOC. [GRACENet publication]

Last Modified: 4/16/2014
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