Enhanced nitrogen retention by lignite during poultry litter composting

Composting is an effective method to transform organic wastes into soil amendments. However, significant nitrogen (N) is lost through ammonia (NH3) volatilization during composting. This work evaluated the effect of lignite amendment (0% (CK), 5% (T1), 10% (T2), 15% (T3)) on N transformation during composting. The results showed T3 increased total nitrogen content by 25% (33.0 g kg(-1) in T3 vs 21.0 g kg(-1) in CK), and increased mineral N by >60% compared with CK. The X-ray photo-electron spectroscopy and Boehm's titration analysis showed that composted T3 contained higher total acid groups than composted CK. Notably, the abundances of ammonium oxidizers decreased in all lignite treatments. High moisture content and low NH3 availability could suppress ammonia oxidizers, therefore improved N retention. Partial least-squares path modeling suggested that physiochemical properties played a dominant role in N loss in composting with or without lignite, however, acid group content appeared to be able to strongly inhibited N loss by adsorption NH4+ under composting with lignite addition. The results of this study suggested lignite addition at 15% as a proper ratio for composting to achieve fast organic degradation and great N retention. (C) 2020 Elsevier Ltd. All rights reserved.