Microbiology and Nitrogen Mineralization in Composted Poultry Litter Amended with Biodiesel Wash Water

Abstract

Composting of poultry litter is an important method to increase the retention of nutrients such as nitrogen (N) prior to its use as an agricultural soil amendment. Biodiesel wash water (BWW) was used as a treatment during composting and compared to municipal water as a control. Molecular analyses examined the effects of BWW on the microbial communities (via denaturing gradient gel electrophoresis) and the abundance of bacteria, fungi, pathogens, and ureolytic/uricolytic N-cycling microorganisms (via quantitative real-time PCR). The lack of large community perturbence and variable abundance of N-cycling microbes supports the use of BWW, but higher levels of Campylobacter in the mature BWW compost will need to be examined further. Ureolytic screening of bacterial isolates identified the dominant group PLUP (poultry litter urease producers). Incubation of PL with BWW and PLUP microbial inoculant, revealed active ureolysis by PLUP, and inhibition of the enzymes involved in N-mineralization by BWW.