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Fluid Journal : Fluid Journal 2005-2007
SPRING 2007 Fluid Journal 17 DR. ARDELL HALVORSON AND CURTIS REULE Conversion of native grasslands to cultivated cropland generally has resulted in a significant decline in soil organic matter and soil organic carbon with conventional-till under dryland conditions. Researchers have reported that after 27 years of no-till and intensive crop management at Nebraska sites, soil organic levels under no-till were 85 percent of native sod levels whereas soil organic levels in conventional- till, crop-fallow production systems were 40 percent of native sod levels. They also reported that soil organic matter declined with plow tillage under an irrigated sugarbeet/small grain rotation, but that the loss of soil organic matter was reduced with high N rates. Under irrigated agriculture and with reduced-till, crop residue levels (both above and below ground) may be sufficient to increase soil organic carbon storage in the Great Plains. Irrigated corn produces a large How To Enhance Soil Organic Carbon Sequestration Texas studies show optimizing crop yields and reducing soil erosion via proper management practices are paying dividends not only environmentally but in crop yields as well. SUMMARY Six-year trends show that soil organic carbon and total soil nitrogen (N) levels are increasing and producing optimum crop yield levels at two grower sites in Texas via the effects of proper crop and fertilization management practices on both corn and wheat grain. Residual soil NO3-N levels have increased since 1999. However, although sufficient N needs to be applied to optimize irrigated crop yield and economic returns, only the amount needed for optimum yield should be applied to minimize NO3-N leaching potential. Another year of data collection is being conducted to verify the trends in soil organic carbon sequestration. quantity of residue that is returned to the soil surface each crop year. In our studies, about 10,000 lbs/A of corn residue has been returned annually to the soil. With this level of residue input to the soil, the object was to determine if application of liquid N to the residue after harvest (N2 sites) would enhance residue decomposition and soil organic carbon sequestration, knowing at the same time that applying N to the residue may also increase the amount of N available for leaching. Information is limited on the long-term effects of crop management practices on crop residue production and its subsequent effects on soil organic carbon and total soil nitrogen in irrigated cropping systems in the Great Plains. The object of the project reported here is to evaluate the influence of crop management practices on residue production, total soil N, soil organic carbon sequestration, and soil NO3-N leaching potential from irrigated locations in north Texas. Grain/residue yield Dalhart. At the Dalhart location, hand-harvested corn grain yields averaged 216 and 168 bu/A for the N1 and N2 sites, respectively, from 1999 to 2005. Average combine- harvested corn yield in 2005 for the N2 half of the pivot was 190 bu/A (excluding the outer edge of the field) and 26 bu/A for the hand- harvested N2 sampling sites located in the outer edge of the field, which
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