Impact of biofertilizers from goat and sheep manure on rhizospheric microbial community of Cenchrus ciliaris

Use of biofertilizers has been increasing to enhance plant growth, yet less attention has been given to their effects on the microbial community and functional composition of the rhizosphere. In this study, biofertilizers produced from sheep (BO) and goat (BC) manure were tested at concentrations ranging from 0 to 10% of soil volume over two vegetative cycles of Cenchrus ciliaris. As expected, biofertilizer application increased CFU counts of coliforms and microbial biomass carbon (MBC). However, the effects on rhizospheric soil biological and chemical properties varied depending on the biofertilizer source. BO increased organic matter (OM) content, whereas BC increased some nutrients, electrical conductivity and the number of total fungi while reducing the number of glomerospores and mycorrhizal colonization. Higher relative abundance of OTUs was found with pure BO, indicating that its application increased microbial diversity and functional composition compared to BC. Moreover, biofertilizer application in the second vegetative cycle suggested that its continuous use may impact the rhizospheric microbial community. These results suggest that the source of biofertilizer and the application of parsimonious doses may prevent the loss of microbial diversity and maintain rhizospheric soil functional capacity.