Modeling organic carbon dynamics under no-tillage and plowed systems in tropical soils of Brazil using CQESTR.

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Effects of Tillage and Nitrogen Fertilizers on CH4 and CO2 Emissions and Soil Organic Carbon in Paddy Fields of Central China

Quantifying carbon (C) sequestration in paddy soils is necessary to help better understand the effect of agricultural practices on the C cycle. The objective of the present study was to assess the effects of tillage practices [conventional tillage (CT) and no-tillage (NT)] and the application of nitrogen (N) fertilizer (0 and 210 kg N ha−1) on fluxes of CH4 and CO2, and soil organic C (SOC) sequestration during the 2009 and 2010 rice growing seasons in central China. Application of N fertilizer significantly increased CH4 emissions by 13%–66% and SOC by 21%–94% irrespective of soil sampling depths, but had no effect on CO2 emissions in either year. Tillage significantly affected CH4 and CO2 emissions, where NT significantly decreased CH4 emissions by 10%–36% but increased CO2 emissions by 22%–40% in both years. The effects of tillage on the SOC varied with the depth of soil sampling. NT significantly increased the SOC by 7%–48% in the 0–5 cm layer compared with CT. However, there was no significant difference in the SOC between NT and CT across the entire 0–20 cm layer. Hence, our results suggest that the potential of SOC sequestration in NT paddy fields may be overestimated in central China if only surface soil samples are considered

Conservation tillage in Georgia: economics and water resources

Conservation tillage systems have proven effective in reducing soil erosion, but additional benefits to agricultural production, water quality and quantity, and on- and off-site impacts of water loss are often ignored. In spite of known benefits, no specific mention has been made of the use of conservation tillage in the development of the current statewide comprehensive water use plan. We estimate that water savings from the use of conservation tillage on cropland currently in conventional tillage could result in potentially enough water to support 2.8 million people annually in Georgia, and that off-site benefits associated with reduced erosion and improved water quality could be as great as $245 million annually. Based upon these potential benefits, conservation tillage needs to be considered in the formulation of the current policy to conserve and protect the state’s water supply for the future. Conservation tillage warrants recognition as a cost-effective practice to conserve Georgia’s water resources.Sponsored by: Georgia Environmental Protection Division U.S. Geological Survey, Georgia Water Science Center U.S. Department of Agriculture, Natural Resources Conservation Service Georgia Institute of Technology, Georgia Water Resources Institute The University of Georgia, Water Resources Facult

Modeling organic carbon dynamics under no-tillage and plowed systems in tropical soils of Brazil using CQESTR.

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