Effect of various biochar on selected soil properties and agronomical parameters of okra (Abelmoschus esculentus L.) at Rupandehi, Nepal

Biochar is rich in carbon and obtained by carbonization of biomass heated at 300-1000°C under limited oxygen which improves the soil properties and yield of various crops. This study aimed to determine the changes in soil properties and agronomical characteristics of okra by biochar prepared from different feedstock. The research was conducted in randomized blocks and replicated thrice, with treatments; control, wood ash (WA), rice husk biochar (RHB), bamboo biochar (BB), Ashoka leaves biochar (ALB), coconut husk biochar (CHB), and sawdust biochar (SB), applied at 18 t/ha. Biochar-incorporated soil and the biochar were analyzed for pH, electrical conductivity, nitrogen, P2O5, K2O, and organic matter, and the soil for bulk density, particle density, and porosity. Agronomical parameters like plant height, fruit size, and yield were also recorded. The biochar incorporation modified the soil's chemical properties and significantly decreased bulk and particle density. The highest reduction of 10.9% in bulk density (1.22gm/cm3), and 4.4% in particle density (2.39gm/cm3) were observed in ALB and SB incorporated soil respectively. ALB (50%) followed by BB (49%) showed a significant increase in soil porosity compared to the control (45.18%). BB (15.7cm) significantly increased the fruit size compared to the control (14.06cm) followed by ALB (15.5cm). ALB (8.16t/ha) significantly increased the yield of okra relative to control (7.82t/ha). The findings suggest the use of ALB and BB to improve soil properties and yield in the long run.