Co-application of wood distillate and biochar improves soil quality and plant growth in basil (Ocimum basilicum)

Background: Nowadays, an ever-increasing attention toward eco-friendly and sustainable agricultural practices, such as the use of biological fertilizers that do not alter the ecological balance of soil, has been grown worldwide. Aim: To evaluate the effect of wood distillate (WD), biochar (B), and their combination (BWD) in increasing soil biomass, soil biological activities, and plant growth in basil (Ocimum basilicum L.) by determination of plant biomass. Methods: Plants of basil were cultivated in greenhouse with three different amendments. WD was applied at a 1% dilution through fertigation. B was applied at a rate of 2% (w/w) corresponding to 34 t ha–1. Organic carbon (OC), dissolved organic carbon (DOC), soil microbial biomass carbon (MB-C), and enzymatic activities (dehydrogenase, phosphatase, arylsulfatase, β-glucosidase, and urease) were determined at the end of the cultivation period (4 weeks) in bulk soil and in the rhizospheric soil. The alteration index three (AI3), which calculates the balances between three enzymes and potentially allows to quantify in relative terms the differences between soils due to different management practices, was also determined. Results: WD and B significantly increased OC and MB-C content, whereas B preferentially retains soil DOC species and the organic substance of the WD in the BWD treatment. Phosphatase and urease activities were the most increased with the combination of the two amendments. AI3 in controls suggests that the application of WD and B at the right doses promotes the activity of soil microorganisms, enhancing the soil biological quality. Conclusion: The presence of the two organic sources increased the availability of nitrogen and phosphorus, with a positive response in terms of basil dry biomass. WD and B have been confirmed as suitable and sustainable amendments for potential application in crops cultivation.