Compost-mixed Biochar Improves Saline Soil Properties and Enhances Brassica Oleracea var. Capitata physio-biochemical Responses

The present research aimed to correlate changes in saline soil properties and cabbage agro-physiological attributes under compost-biochar co-application. The treatments used prior to cabbage cultivation were soil applications of compost/biochar mixtrure (CMB) at rates of 0 (CMB0), 10 (CMB10), and 20 (CMB20) t ha–1 in a randomized complete block design with three replications. The CMB20 was the effective practice for reducing dry bulk density, saturated hydraulic conductivity, pH, and electrical conductivity, while improving total porosity, water-holding pores, soil moisture at field capacity, organic matter, cation exchange capacity, and nutrient availability. CMB20 also improved plant relative water content, membrane stability index, and chlorophyll a and b concentrations. Hydrogen peroxide and malondialdehyde decreased by 13.5% each under CMB20 treatment. Cabbage plants grown in saline soil produced greater phenolics content (56.0%) with higher superoxide dismutase (17.2%) activity in CMB20-treated plots than CMB0. Leaf nitrogen, phosphorus, and potassium contents enhanced by 10.1, 28.1, and 18.4%, respectively, compared with CMB0. Finally, CMB20 achieved the maximal improvements in leaf number plant− 1 (41.8%), leaf area plant− 1 (216.2%), above-ground biomass (174.5%), head circumference (38.2%) and marketable yield (101.6%) of cabbage. It could be concluded that amending saline soil with CMB is regarded as a promising treatment for alleviating the salinity hazards on cabbage via modulating soil properties and physiological responses. Hence, CMB application, 20 t ha–1, can be recommended as an agronomic practice for cabbage production to obtain high yield and quality.