Inoculation with nitrogen turnover bacterial agent appropriately increasing nitrogen and promoting maturity in pig manure composting

- The NTB agent prolonged the thermophilic stage.
- Adding 1% NTB agent at the beginning of composting reduced N loss.
- Adding 1% NTB agent at the beginning facilitated TOC degradation.
- Adding 1% NTB agent at the beginning improved the compost quality.

The nitrogen turnover bacterial (NTB) agent, which is closely related to nitrogen turnover, was comprised of a bacterial consortium of ammonifiers, nitrobacteria and Azotobacter in this study. The three constituents of the bacterial consortium were added to pig manure and wheat straw mixtures in different doses and at different times, and subsequently composted to investigate their effects on nitrogen transformation and maturity. Throughout the period, the total N loss was 35-56%, 10.7-22.7% of which consisted of NH3, and 18-35% of the initial organic carbon was degraded. Adding the NTB agent prolonged the thermophilic stage by one to six days compared to the control. The lowest N loss (35%), the highest degradation rate of organic carbon (35%) and the greatest increase in total nitrogen content (36.1%) occurred in the inoculation with 1% NTB agent at the beginning of composting. However, adding 1% NTB agent after the thermophilic stage and 3% NTB agent at the beginning of composting had no positive effect with respect to retaining nitrogen or accelerating the maturation process. Therefore, the inoculation with 1% NTB agent at the beginning of composting was effective for reducing N loss and promoting maturity.