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United States Department of Agriculture

Agricultural Research Service

Title: Flush of Co2 Following Rewetting of Dried Soil Relates to Active Organic Pools

Authors
item Franzluebbers, Alan
item Haney, R - TEXAS A&M UNIVERSITY
item Honeycutt, Charles
item Schomberg, Harry
item Hons, F - TEXAS A&M UNIVERSITY

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 18, 1999
Publication Date: N/A

Interpretive Summary: Soil quality assessment could become more standardized with the development of a simple, rapid, and reliable method for quantifying potential soil biological activity. We evaluated the flush of CO2 following rewetting of dried soil under standard laboratory conditions as a method to estimate an active organic matter fraction. Using 20 different soil series from four different regions (Alberta, cold/dry; Maine, cold/wet; Texas, hot/dry; Georgia, hot/wet), we found excellent correlations between the flush of CO2 during the first three days of incubation and microbial biomass and activity. Accounting for geographical differences in mean annual temperature and precipitation, which affect the quality of soil organic matter, further improved relationships between the flush of CO2 following rewetting and various well-defined pools of organic matter. Measuring the flush of CO2 following rewetting of dried soil can be recommended for routine soil testing of biological soil quality, because it (i) reflects microbial biomass and activity, (ii) shows a prompt and accurate response to management, (iii) integrates soil physical, chemical, and biological conditions during incubation, (iv) appears to be broadly applicable across soil texture and management systems, and (v) would be readily and economically accessible.

Technical Abstract: We evaluated the flush of CO2 following rewetting of dried soil under standard laboratory conditions as a method to estimate an active organic matter fraction. The flush of CO2 following rewetting of dried soil (3 d incubation at 50% water-filled pore space and 25 C) was assessed for 20 soil series containing a wide range of organic C (20+/-13 g/kg) from Alberta/British Columbia, Maine, Texas, and Georgia. The flush of CO2 following rewetting of dried soil explained 97% of the variability in C mineralization during 24 d (n=471), 86% of the variability in soil microbial biomass C (n=399), and 67% of the variability in net N mineralization during 24 d (n=327). Accounting for geographical differences in mean annual temperature and precipitation, which affect the quality of soil organic matter, further improved relationships between the flush of CO2 following rewetting and active, passive, and total C and N pools. Measuring the flush of CO2 following rewetting of dried soil can be recommended for routine soil testing of biological soil quality, because of its (i) strong overall relationships with active organic pools, (ii) predictable change in relationships with active organic pools based on climatic variables, (iii) simple setup with minimal equipment requirements, and (iv) rapid analysis time.

Last Modified: 8/1/2014
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