Nutrient transformation during aerobic composting of pig manure with biochar prepared at different temperatures

Abstract

The effects of the corn stalk charred biomass (CB) prepared at different pyrolysis temperatures as additives on nutrient transformation during aerobic composting of pig manure were investigated. The results showed that the addition of CB carbonized at different temperatures to pig manure compost significantly influenced the compost temperature, moisture, pH, electrical conductivity, organic matter degradation, total nitrogen, and NH₃ variations during composting. Compared with control and adding CB charred at lower temperature treatments, the addition of CB prepared over 700°C resulted in higher pH (over 9.2) and NH₃ emission and lower potherb mustard seed germination index value during the thermophilic phase. Peak temperatures of composts appeared at 7 days for control and 11 days for CB added treatments. During 90 days composting, the organic matter degradation could be increased over 14.8–29.6% after adding of CB in the compost mixture. The introduction of CB in pig manure could prolong the thermophilic phase, inhibit moisture reduce, facilitate the organic matter decomposition, reduce diethylene triamine pentaacetic acid (DTPA) extractable Zn and Cu contents in pig manure composts and increase ryegrass growth. The study indicated that the corn stalk CB prepared around 500°C was a suitable additive in pig manure composting.

Keywords:

• compost
• biochar
• carbonized temperature
• pig manure
• nutrient transformation

Acknowledgements

Funding for this research was provided by National Natural Science Foundation of China (No. 41101288), Shannxi Province Natural Science Foundation of Research Projects (No. 2013JM3011) and Northwest A&F University Young Scholar Research Projects (2014YB064). Mr. Yanjun Yin in Northwest A&F University was thanked for his constructive advices. Jiaojiao Zhou, Xuan Wang and other students who took part in the 2013 Undergraduate Research Project of Northwest A&F University were also thanked for their help. The anonymous reviewers are gratefully acknowledged for their valuable comments and suggestions that helped to substantially improve this article.