Microbial community structure and functionality under peanut-based cropping systems in a sandy soil

Little information is available on soil microbial and biochemical properties, important for understanding nutrient cycling and organic matter dynamics, as affected by different peanut cropping systems and how they relate to soil functioning. Thus, we studied a Tifton loamy sand (fine-loamy, kaolinitic, thermic Plinthic Kandiudults) in Georgia, which is first in peanut production in USA, after 5 and 8 years under continuous cotton (Gossypium hirsutum, L) (CtCtCt), cotton-cotton-peanut (CtCtPt), corn (Zea mays L.)-peanut-cotton (CrPtCt), peanut-peanut-cotton (PtPtCt), and continuous peanut (PtPtPt). Soil organic carbon (OC) at 0-20 cm was already higher under PtPtPt (average, 8.7 g C kg(-1) supercript stop soil), PtPtCt (average, 7.7 g C kg(-1) soil), and CrPtCt (average, 7.8 g C kg(-1) soil) compared with CtCtPt (average, 4.7 g C kg(-1) soil) and CtCtCt (average, 3.3 g C kg(-1) soil). Similarly, alkaline phosphatase, acid phosphatase, and phosphodiesterase as a group showed higher activities under PtPtPt, PtPtCt, and CrPtCt than under CtCtPt and CtCtCt. The activities of glycosidases (alpha-galactosidase, beta-glucosidase, and beta-glucosaminidase) as a group were more sensitive to the cropping systems than phosphastases and showed a distinctive cropping system separation as follows: PtPtPt=CrPtCt > PtPtCt > CtCtPt > CtCtCt. Similar to OC and microbial biomass C trends, distinctive differences were found in the microbial community structure of this sandy soil after 8 years between peanut-based cropping systems (CrPtCt, PtPtCt, and PtPtPt) and cotton-based cropping systems (CtCtCt and CtCtPt) as indicated by the fatty acid methyl esters profiles.