Designer compost with biomass ashes for ameliorating acid tropical soils: Effects on the soil microbiota

In a greenhouse study we investigated the potential of wood ash amended composts to ameliorate acid tropical soils. Three composts (produced with 0%, 8%, 16% wood ash admixture, respectively), and two acid tropical soils, an Oxisol and an Ultisol from Cameroon were used for that purpose. In this paper we report the effects on the soil microbiota at the end of the cropping cycle (100 days soybean plus 100 days fallow). Principal coordinate analysis of denaturing gradient gel electrophoresis patterns of ammonium oxidizing bacteria (AOB) indicated that they were stimulated by addition of compost. AOB communities of the compost treated soils differed from the control ones, and no significant differences among the different composts were found in both soils. Soil type clearly influenced the AOB community. Ester-linked phospholipid fatty acids increased in compost treated soils, up to an ash amendment of 8%.