Author
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Reicosky, Donald |
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Submitted to: International Soil Conservation Organization (ISCO)
Publication Type: Proceedings Publication Acceptance Date: 3/6/2001 Publication Date: N/A Citation: N/A Interpretive Summary: The increase in the carbon dioxide in the atmosphere related to concerns about potential global warming and prospects of using soil as a sink for carbon has attracted interest. The cumulative effect of tillage and many cropping rotations has been a 30-50% decrease in soil carbon that causes undesirable changes in soil physical, chemical and biological properties. Recent studies involving tillage methods indicate major gaseous loss of carbon immediately after tillage. This work evaluates the impact of various conservation tillage tools and strip tillage on tillage-induced CO2 loss. Conservation tillage tools that leave more residue on the surface had only 31% of the CO2 loss caused by the moldboard plow. Strip tillage decreased the amount of CO2 loss and appears to be related to the volume of soil disturbed. Progress is being made in developing conservation tillage tools that can further enhance soil carbon management. These results are significant to farmers and policy makers in that intensive tillage results in substantial short-term gaseous losses of CO2. This information will assist scientists and engineers in developing improved tillage methods to minimize the gaseous loss and to improve soil carbon management. Farmers can develop and utilize new management techniques for enhancing soil carbon by increasing the quantity and quality of crop residues and by changing the type and intensity of tillage. This information will be of direct benefit to the farmers to enable them to maintain crop production with minimal impact on air quality and the environment. Technical Abstract: The magnitude of greenhouse gas emissions from soil degradation depends on land use, cropping systems and tillage intensity. Concern for soil quality and related environmental issues requires new knowledge to minimize agriculture's impact on the environment. Agricultural ecosystems can play a significant role in the production and consumption of greenhouse gases, specifically carbon dioxide. Information is needed on the mechanisms and magnitude of greenhouse gas emission from agricultural soils with specific emphasis on tillage mechanisms. This work evaluates the impact of various conservation tillage tools and strip tillage on tillage-induced CO2 loss. Results showed the maximum CO2 loss following the moldboard plow with less CO2 loss from various conservation tillage tools and the least from no-till. Strip tillage decreased the amount of CO2 loss and appears to be related to the volume of soil disturbed by the tillage operation. Additional information on CO2 loss from the soil without using the portabl chamber was collected to characterize the plume of CO2 from a plowed strip 5.5 m wide by measuring the concentration up and downwind. Concentration differences decreased with time after tillage and were as large as 140 mmol mol**-1 immediately after tillage. The smaller CO2 loss from conservation tillage tools is significant and suggests progress in developing conservation tillage tools that can lead to soil carbon enhancement. Reducing the volume of soil disturbed through strip tillage should enhance soil and air quality by increasing the labile carbon content and decreasing the tillage-induced CO2 losses. These results suggest that soil and environmental benefits of less intensive tillage should be considered in soil management decisions. |
