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Title: Flush of CO2 as a short-term biological indicator of soil nitrogen mineralization in the Southeast

item PERSHING, MARY - North Carolina State University
item CROZIER, CARL - North Carolina State University
item SCHROEDER-MORENO, MICHELLE - North Carolina State University
item OSMOND, DEANNA - North Carolina State University
item Franzluebbers, Alan

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/15/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Determining the appropriate nitrogen (N) rate is critical to farm economics and environmental protection. In North Carolina, N fertilizer recommendations are not modified by residual inorganic N or biologically active N, but only by realistic yield expectation set for each soil type by crop. However, due to increasingly popular conservation management practices such as cover cropping and no-till farming, residual N can remain in the soil in a biologically active form for potential plant uptake, resulting in greater supply of N than expected. Measuring biologically active carbon (C) is faster, more accurate, and less expensive than measuring biologically active N. Soil samples (120) were collected from field stations representing the three physiographic regions of North Carolina (coastal plain, piedmont, and mountains) to use in a greenhouse trial. Unfertilized Sorghum bicolor was planted for the greenhouse trial and harvested at 4 and 8 weeks. Dry matter accumulation and N concentration were measured, which allowed for determination of N uptake. Carbon mineralization, or the “flush of CO2”, was measured for each soil, as was microbial biomass C using fumigation-incubation, prior to the greenhouse trial. Mean plant dry matter accumulation was linearly related to the flush of CO2 with an r2 of 0.78. Soil microbial biomass C was linearly related to the flush of CO2 with an r2 value of 0.80. These data, as well as total, particulate, and inorganic N, will contribute to a larger database of laboratory incubations and greenhouse trials to help understand nutrient dynamics and improve accuracy of fertilizer N recommendations in the Mid-Atlantic and southeastern USA.