A group from School of Minerals Processing and Bioengineering, Central South University, Changsha, China, etc. has reported that fumigation treatment was better than bioagent treatment in continuous cropping fields.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9354655/
Continuous cropping alters soil physiochemical properties and microbial community, causes soil salinization and acidification, accumulates harmful microbes, reduces fertilizer efficiency, and leads to severe soil-borne diseases, resulting in yield reduction and huge economic losses in agriculture production.
In this study, fumigation and biological agent treatments were evaluated to alleviate continuous cropping barriers. Three fumigation treatments, namely, chloropicrin (FM1), dazomet (FM2), and untreated control (CK_FM), and three biological treatments, namely, two biological agents (AG1 and AG2) offered by Prof. Jian Ye from the Institute of Microbiology, CAS, and untreated control (CK_AG) were compared.
Compared with the biological agent treatment, fumigation treatment had stronger disease inhibition effects. Furthermore, not only did the fumigation treatment increase pH, but it also increased nutrient availability in soil and stimulated crop growth.
The bacterial diversity was significantly reduced by the application of fumigants, compared with the biological agents, which caused a significant increase in bacterial diversity. This could be explained by the fact that fumigation chemicals are often toxicants to organisms. Fumigants are well-known poisonous substances used in killing insects, nematodes, and other animals or plants that cause damage to foods, seeds, or human dwelling. Although it is widely accepted that the diverse soil microbial community would benefit above-ground crops against disease infection and promote plant growth, this was in contrast to the results obtained in this study for fumigation treatment.
This can be explained as follows: fumigation treatment disrupted the entire soil microbial ecosystem and also leaded to changes in soil characteristics and plant performance, and thereby the crop benefitted from the reassembled rhizosphere microbiome resulting in the effective alleviation of continuous cropping barriers.