Eggplant growth in wheat straw-, wheat straw biochar- and compost-amended soils: a field study of CO2 emission dynamics, soil physicochemical, microbial, and nutrient effects

•Wheat straw biochar was prepared in a proprietary kachcha reactor (Indian patent no. 380921), designed using locally sourced clay.•WSBM, WSBC and compost combinations were used as soil amendments in the eggplant growth study.•Amendment effects on eggplant growth parameters, soil properties, soil CO2 efflux and microbial biomass carbon was evaluated.•Eggplant fruits were classified using the USDA method (Fancy, US No. 1, US No. 2, and Culls), and highest number of fruits (42) was produced from biochar + compost amendments.•Biochar, along with biochar combined with compost amendments, yield the most substantial overall enhancements in the soil and plant growth parameters examined in the study.