Measurement and analysis of biogas fertilizer use efficiency, nutrient distribution and influencing factors of biogas residues and slurry on pig farms

Abstract

Although the effects of biogas residues and slurry returning to farmland are good, they still cannot be used widely in China. In this study, the biogas fertilizer use efficiency, nutrient distribution and influencing factors of fertilizer use efficiency of biogas residues and slurry in 20 biogas projects in Chongming County, Shanghai, China were measured and analyzed. The correlation and a linear regression fit of parts of test indicators were also analyzed. The results show that pig farm biogas residues and slurry mixture are nutrient-rich and can be used as a high-quality organic fertilizer, while its fertilizer use efficiency is unstable because of the differences among area, raw materials, fermentation technology and operation management. Nutrients are not evenly distributed in biogas residues and slurry. Higher levels of organic matters, P and trace elements were detected in biogas residues and higher levels of water-soluble N and K were detected in biogas slurry. The correlations between some test indicators of biogas residues and slurry mixture are significant, especially between total K and conductivity. Linear regression model fitting results of parts of test indicators are satisfactory. Hence, the values of the other test indicators can be estimated by one known indicator which can effectively reduce the determination workload under some limited situations.