Ryegrass (Lolium multiflorum L.) and Indian mustard (Brassica juncea L.) intercropping can improve the phytoremediation of antibiotics and antibiotic resistance genes but not heavy metals

Research team of safety utilization of unconventional water resources, institute of farmland irrigation of CAAS, has made important progress in phytoremediation of soil heavy metals-antibiotics-ARGs (antibiotic resistance genes) combined pollution caused by long-term swine manure and slurry application. We conducted a field experiment to comprehensively investigate the effects of intercropping (L. multiflorum and B. juncea) on the removal of combined pollutants, providing theoretical basis and technical support for the application of phytoremediation technology in the remediation of combined polluted soil. Relevant achievements are published online in Science of the Total Environment.

Intercropping, which is an economical and effective cropping pattern, has an advantage over sole cropping in ameliorating plant growth and affecting the soil environment. We hypothesized that intercropping would result in minimal soil accumulation and maximum plant uptake when compared with sole cropping. The results showed that the competitive interaction between antibiotics and heavy metals would affect their mobility, making the removal of heavy metals more difficult. Compared with sole cropping, intercropping of L. multiflorum and B. juncea could improve the removal efficiency of different kinds of antibiotics by 4.48%–100.00% by increasing plant accumulation and the contents of some members of phyla (Actinobacteria, Bacteroidetes, and Proteobacteria). Moreover, intercropping resulted in lower ARGs abundance, especially in the rhizosphere of L. multiflorum and B. juncea. MGEs (mobile genetic elements) and bacterial community, and soil properties and MGEs were the main factors impacting the ARGs variation in rhizosphere and bulk soil, respectively.

This study was financially supported by Agricultural Science and Technology Innovation Program (ASTIP) of Chinese Academy of Agricultural Sciences; Scientific and Technological Project of Henan Province; National Key Research and Development Program of China; National Natural Science Foundation of China.