46 / 2021-06-29 16:09:12

Comparison the phytotoxicity of different livestock manures with heap retting

Livestock manure; Heap retting; Seed germination index; redundancy analysis; Correlation analysis

Comparison the phytotoxicity of different livestock manures with heap retting

Yilin Kong, Guoying Wang, Guoxue Li, Jing Yuan ^*

Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation, College of Resources and Environmental Science, China Agricultural University, Beijing 100193, China

This study investigated the fate of phytotoxicities during heap retting with four kinds of livestock manures (chicken, pig, sheep and cattle manure), and analyzed the correlations with four types of seed (cucumber, radish, Chinese cabbage, oilseed rape) by germination assays. Results indicated that all treatments did not meet the harmless requirements of organic fertilizer at the end of heap retting. The decreased concentrations of dissolved organic carbon (DOC) and dissolved nitrogen (DN) were found during all treatments (24.43%~56.72%), the degration of chicken manure was lowest and there were high amount of volatile fatty acids (VFAs) and NH₄⁺ in this pile. Germination index (GI) of the four kinds of seeds in chicken manure were 0, while in sheep and cattle manure it was much higher (45.99%~105.75%) at the end of treating process. The bacterial community structures were significantly different among the four manures, which were mainly affected by the DN content reflected by redundancy analysis. Correlation analysis showed that GI had significantly negative correlations with VFAs，DOC and DN in all composts (P<0.05), which proved that VFAs and NH₄⁺ led to the significant inhibition of GI in chicken manure trail. These findings in the present study can provide important theoretical basis for the evaluation of heap retting process with different livestock manures and the safety application of retting manure in farmlands．

Key words: Livestock manure; Heap retting; Seed germination index; redundancy analysis; Correlation analysis