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Title: REVIEW OF ELEVATED ATMOSPHERIC CO2 EFFECTS ON AGRO-ECOSYSTEMS: RESIDUE DECOMPOSITION PROCESSES AND SOIL C STORAGE

Author
item Torbert, Henry - Allen
item Prior, Stephen - Steve
item Rogers Jr, Hugo
item WOOD, C - AUBURN UNIV

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Scientist have become concerned with the increasing concentration of carbon dioxide (CO2) in the atmosphere and its potential to induce changes to the environment on a global scale. For example, this increase has led to concerns regarding the possibility of global warming. A highly debated hypothesis is that CO2 is being removed from the atmosphere by plants and is being stored in soil in the form of organic carbon. Recently, efforts have been made to promote the process of soil carbon storage to remove more CO2 from the atmosphere. Understanding how CO2 is cycled is important if we are to increase our ability to store C in the soil. This study examined how plants grown under different levels of atmospheric CO2 decomposed after they died. Data indicated that there is a potential for carbon from atmospheric CO2 to be stored in soil under agriculture production systems, but the potential storage of carbon may be different for different crops. The findings of this study demonstrate the importance of further research for developing mitigation strategies for global change based upon wise management practices.

Technical Abstract: The impact of elevated CO2 on soils in agro-ecosystems is important on a global scale because soil C storage may be altered by management. A series of studies using major crops were reviewed to examine the impact of elevated CO2 on crop residue decomposition within agro-ecosystems. Laboratory incubation studies using soil collected after cotton and wheat were conducted to examine the impact of Free Air CO2 Enrichment (FACE) on soil C and N cycling. Results indicated that FACE could lead to increased soil C storage. Further study revealed that CO2-induced changes in cotton could alter N mineralization which was dependent on plant organ and soil series. Incubation studies utilizing soybean and grain sorghum grown in OTC indicated that N mineralization was reduced with elevated CO2 in both species. Over 14 d, little difference was observed for CO2 treatments in soybean, but C mineralization was reduced with elevated CO2 in grain sorghum. For 60 d, a reduction in CO2-C mineralized per g of residue added was observed with the elevated CO2 treatment in both crop species. Results agreed with those from the OTC field observations. Observations from field and laboratory studies indicate that with elevated CO2, the rate of plant residue decomposition may be limited by N and the release of N from decomposing plant material may be slowed. This indicates that understanding N cycling as affected by elevated CO2 is fundamental to understanding the potential for soil C storage on a global scale.