Abstract

Low phosphorus (P) availability is a main limiting factor for plant growing on ash-derived volcanic soils (Andisols). Andisol soils have more than 85% of phosphate retention, which reduces severely the plant growth rates. The high dung concentrations present in grazing pastures contribute to high input of P and phosphatase enzymatic activity by microorganisms, increasing the P availability in the rhizosphere. Lolium perenne L is the most important grazing species in southern Chile. Towards a better understanding of dung influence in L. perenne growth, rhizosphere ecology and P availability, we evaluate three cow dung treatments (200, 400 or 600 g P kg-1 soil) using the rhizobox system and grown under greenhouse condition. Bacterial community structure in the rhizosphere was assessed by denaturing gradient gel electrophoresis (DGGE), culturable rhizobacteria in soil and dung was quantified. The results showed changes in bacterial communities compared with controls and different soil treatments, according to the results the greatest contribution of bacteria is given by the soil compared with the dung.