To explore the effects of C/N ratios on the physicochemical properties and microbial com-munity diversity during the composting process of wolfberry branch powder for horticultural substrate production,this study used Ningxia wolfberry branch powder as base material and urea as the nitrogen source.The original mixtures were adjusted to C/N ratios of 15(W1),20(W2),25(W3),30(W4),35(W5),and 43.75(W6).The results showed that during the composting process,for all treatments,the pH and conductivity showed a gradually decreasing trend,while the total nitrogen content a gradually increasing trend.The ammonium nitrogen content showed a first increasing and then decreasing trend,while the nitrate nitrogen content increased first,then decreased and increased again.During the composting process,cellulase activity was significantly different among treatments.Specifically,it showed a continuous upward trend under the treatments W2,W3,W4 and W5 when C/N was 20-35.However,it showed a small upward trend in the early composting period(0-15 days)and a slow downward trend in 15-105 days when the C/N was too low(15)or too high(43.75).With respect to urease,it increased first,then decreased and increased again.When C/N was 20,the degradation rate of cellulose and hemicellulose and the increment value of lignin showed the highest values.At the genus level,Pandoraea,Nitrosomonas,Nitrosospira,Pseudomonas,Paracoccus,Thauera,Acidihalobacter,Ovis,Massilia,Nitrobacter,Actinoplanes and Sulfitortus were all dominant bacterial groups.When C/N was higher(C/N≥25),there were significantly in-creasing trends for the species number,species diversity,richness and species uniformity of the mi-crobial community in the composting pile of CMS.Based on PCA analysis,C/N value 25 was the crit-ical value of ammonification and nitrification,and C/N value 35 was the critical value of denitrifica-tion.H ence,to expedite the composting process and minimize nitrogen loss,it is recommended to maintain the initial C/N ratio of the composting pile within the range of 20-25.
Wolfberry branch powderFermentationC/NPhysicochemical propertiesNitrogen conversionMicrobial community
万方数据
维普
