Optimizing compost quality: carbon-to-nitrogen ratio and nitrogen content in co-composting livestock manures
2023
Nurin, A.Y. | Lee, T.P. | Chin, N.L. | Nayan, N.
The mass production of horse manure (HM) and chicken manure (CM) can be effectively managed by harnessing their complementary effects through co-composting with sawdust (SW) as a bulking agent. To analyze the impact of various factors on the compost quality, response surface methodology (RSM) was employed. Four independent factors were considered at five levels: HM:CM composition (0:100, 25:75, 50:50, 75:25, 100:0), particle size (0.25cm, 0.50cm, 0.75cm, 1.0cm, 1.25cm), composting period (25 days, 30 days, 35 days, 40 days, 45 days), and bulking agent amount (5%, 10%, 15%, 20%, 25%). The quality particle parameters evaluated were C carbon-to-nitrogen (C/N) ratio and nitrogen content. Central composite design (CCD) was used to determine the relationship between the independent factors and the responses. The optimal conditions for co-composting HM and CM were determined as follows: HM:CM composition of 87:13, particle size of 0.5 cm, composting period of 32 days and 20% of SW content, producing C/N ratio of 20.1 and 2.1% N. The experimental values closely aligned with the predicted values, with a root mean square predicted error (RMSPE) of less than 0.50. This study has proven that RSM and CCD are effective in determining optimal process parameters and developing polynomial models for predicting responses in the co-composting of HM and CM. Furthermore, the co-composting of HM and CM with SW as a bulking agent yielded an optimal C/N ratio and high nitrogen content which can enhance nutrient mineralization, leading to improved soil health and fertility. The findings highlight the potential of utilizing co-composted HM and CM as a valuable resource for sustainable agriculture practices.
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