Contrasting resilience of soil microbial biomass, microbial diversity and ammonification enzymes under three applied soil fumigants

Abstract

Fumigation is a widely applied approach to mitigate the soil-borne diseases. However, the potential effects of currently applied fumigants on ammonification remain unclear. An 84-day incubation experiment was conducted based on non-fumigated soil (CK) and fumigated soil using three common fumigants, i.e., chloropicrin (CP), 1,3-dichloropropene (1,3-D), and metam sodium (MS). The results showed that, the three fumigants all decreased the microbial C, and the largest reduction (84.7%) occurred with the application of CP. After fumigation, the microbial diversity in the CP treatment rapidly recovered, but that in the 1,3-D treatment decreased and did not recover by the end of the experiment. The application of MS showed no impact on the microbial diversity during the assay, indicating that significantly different microbial diversity can be achieved by choosing different fumigants. Furthermore, the three fumigants showed divergent effects on the enzymes involved in ammonification. The analysis showed that the enzyme variation with CP application was mainly associated with the changed microbial C and N (P<0.05), and not with the microbial community, which was different from the observed effects of 1,3-D or MS application. In addition, the soil quality index showed that CP was still significantly harmful at the end of incubation compared with the good resilience of MS, indicating that CP may not be a suitable fumigant.