The secondary compost products enhances soil suppressive capacity against bacterial wilt of tomato caused by Ralstonia solanacearum

Abstract

Composting crop residues and animal manures for CO2 fertilization of vegetable crops is popular in China, but its rapid adoption in greenhouses faces a roadblock: the public concern over the disposition of much large amounts of compost products. In the present study, we used a secondary compost process to re-use the compost products, and evaluated the effect of secondary compost products (SCP) on tomato bacterial wilt in three field trials. The results showed that SCP application had great potential for the control of tomato bacterial wilt. Compared with the control (local conventional cultivation), SCP application decreased the disease incidence by 32–81% and increased fruit yields by 59–95% across the three trials. Irrespective of treatment, significant correlations were found between Ralstonia solanacearum populations and total nitrogen, soil organic carbon and NO3−-N contents. Moreover, the severity of bacterial wilt negatively associated with the activity of phosphomonoesterase and β-d-glucosidase, FDA hydrolysis, soil respiration, microbial biomass carbon and bacterial community diversity, whereas positively related with fungal community diversity. The results indicate that the enhancement of soil suppressiveness against R. solanacearum by SCP application was likely due to the alteration of microbial community structure and increased competitive ability of beneficial microorganisms with pathogens. We concluded that SCP application, as a way of re-utilization of compost products have the ability to increase soil suppressive capacity against bacterial wilt.