Effects of intercropping of peanut with the medicinal plant Atractylodes lancea on soil microecology and peanut yield in subtropical China

Diverse intercropping is an effective way to control crop disease and improve productivity. The aim of this study was to investigate the effects of intercropping peanut (Arachis hypogaea L.) with the medicinal plant Atractylodes lancea on peanut yield and on the microbial community in the soil. A. lancea was intercropped with peanut in an upland that had been monocropped with peanut for 10 years in subtropical China. The results showed that all the intercropping treatments increased the peanut pod yield. Intercropping of peanut with A. lancea effectively reduced the accumulation of soil phenolic allelochemicals and increased soil urease and invertase activities. Compared with addition of fertilizer, the row spacing between peanut and A. lancea was a more important factor influencing the soil microbial community. Analysis of phospholipid fatty acid (PLFA) profiles showed that Gram-negative (G(-)) bacteria were significantly affected by changes in the intercropping pattern. Especially in the rhizosphere region, which is nutrient-rich and has diverse substrate composition, the G(-) bacterial population increase by 31.2-79.9 % in intercropping treatments. Soil G(-) bacteria (as indicated by PLFA, including cy17:0, 18:1 omega 7, and 16:1 omega 9) were significantly promoted in the intercropping treatments. The increase in the G(-) bacterial population and the decrease of phenolic allelochemicals resulted in the promotion of peanut growth and increased peanut yield in the intercropping treatments. Our results provide details on the mechanisms by which intercropping of peanut with A. lancea can improve the soil environment.