Effect of Biochar-Containing Compost on Cucumber Quality and Antibiotic Resistance Genes Abundance in Soil-Cucumber System

The distribution of antibiotic resistance genes (ARGs) derived from compost in soil-plant systems is a serious issue. One possible remedy is the application of biochar-containing compost. In this study, cucumber quality and the abundance of ARGs in soil-cucumber systems under different compost treatments, namely, traditional pig manure and corn straw compost (PC); pig manure, corn straw, and large particle size biochar (5-10 mm) compost (PCLB); and pig manure, corn straw, and small particle size biochar (<2 mm) compost (PCSB); were investigated. The results showed that, under PCSB, the yield, vitamin C and soluble protein content of the cucumbers were the highest, while the absolute abundance of intI2 was reduced in the soil. The amount of available potassium in the soil contributed the most to changes in cucumber yield and quality. The total absolute abundance of ARGs in the soil was highest in PC, followed by PCLB, PCSB, and CK (control treatment without fertilization) treatments. Compared to CK treatments, PCLB and PCSB applications to the soil decreased the abundance of sul1 and tetG by 42-57% and 38-80%, respectively, in the cucumbers. In summary, the PCSB application was more beneficial in increasing soil nutrient content; improving cucumber yield, vitamin C, and soluble protein content; and reducing the risk of input and transport of ARGs in the soil-cucumber system.