Title: Microbial community structure and functionality under peanut based cropping systems in a sandy soil Authors
Submitted to: Soil and Water Conservation Society
Publication Type: Abstract Only
Publication Acceptance Date: July 21, 2007
Publication Date: July 25, 2007
Citation: Acosta Martinez, V., Rowland, D., Sorensen, R.B. 2007. Microbial community structure and functionality under peanut based cropping systems in a sandy soil [abstract]. Soil and Water Conservation Society, July 21-25, 2007, Tampa, Florida. CD-ROM Technical Abstract: There is little information on soil microbial and biochemical properties, important for nutrient cycling and organic matter dynamics, as affected by different peanut (Arachis hypogaea L.) cropping systems and how they relate to soil quality and functioning and system sustainability. We studied a sandy soil (80% sand, 13% clay, pH of 6.1-6.5 at 0-20 cm) in Georgia, USA under continuous cotton ((Gossypium hirsutum) CtCtCt), cotton-cotton-peanut (CtCtPt), corn (Zea mays L.)-peanut-cotton (CrPtCt), peanut-peanut-cotton (PtPtCt) and continuous peanut (PtPtPt). Soil organic C was already higher under PtPtPt (avg: 8.7 g C kg-1 soil), PtPtCt (avg: 7.7) and CrPtCt (avg: 7.8) compared with CtCtPt (avg: 4.7) and CtCtCt (avg: 3.3) after 5 years. The changes in soil organic C dictated the trends of microbial communities and enzyme activities. Three dimensional plots for alkaline phosphatase, acid phosphatase and phosphodiesterase as a group showed higher activities under PtPtPt, PtPtCt and CrPtCt than under CtCtPt and CtCtCt. These results were in agreement with a mycorrhiza indicator fatty acid methyl ester (18:1'9c) providing evidence of increases in the secretion of phosphatases by mycorrhiza associations under peanut. The activities of glycosidases were more sensitive to the cropping systems: PtPtPt=CrPtCt>PtPtCt>CtCtPt>CtCtCt. These findings demonstrate distinctive trends in plant degradation-residue nutrients incorporation into soil. Due to the sustainability problems of continuous peanut (i.e., higher plant pathogens, lower yields) and the low residue incorporation with cotton systems (i.e., CtCtPt or CtCtCt), our results should be considered in management decisions for enhancing soil quality, and potentially influence peanut production under CrPtCt and PtPtCt rotations.