An investigation on the combined amendment of biochar and bioinoculant as a promising plant and soil health promoters

Research in exploring the use of biochar as soil amendment to enhance soil fertility and sequester carbon is upgraded day by day. However, the impacts of different levels of biochar with bioinoculants like Azospirillum on microbial as well as crop growth stimulation are unknown. Hence, a pot culture experiment was conducted to find out the impact of different levels of Acacia wood based biochar with Azospirillum strain AZ204 on the growth of Maize variety PEHM5 under unsterile vertisols. Biochar application at the level of 25 t ha⁻¹ with Azospirillum recorded significantly higher growth parameters like shoot length, root length, girth of stem and total dry weight over other levels of biochar (0, 5, 10, 15 and 20 t ha⁻¹) at 30, 60 and 90 days after sowing. Also, the population size of beneficial soil microbes like Azospirillum and total diazotrophs in the rhizosphere registered maximum at the highest level of biochar (25 t ha⁻¹) application with Azospirillum at all the days of sampling. Furthermore, a significant increase of the native mycorrhizal responses to 25 t ha⁻¹ of biochar with Azospirillum application was also observed in terms of root colonization of maize and spore number in the soil. The experimental results indicated that biochar at higher levels of 25 t ha⁻¹ with Azospirillum inoculation was significantly superior in increasing the uptake of nutrients by maize. This treatment combination also proved efficient in increasing the yield of maize by recording 104.08 g plant⁻¹ and 18.62 g of total cob and 100 grain weight. Thus, biochar amendments at the rate of 25 t ha⁻¹ with Azospirillum is indeed capable of improving nutrient availability as well as microbial activity in vertisol resulting in a significant increase (upto 60%) in yield of maize. Thereby, the addition of biochar at the level of 25 t ha⁻¹ to soil with Azospirillum has the potential to bring in a significant plant-microbial responses, ultimately leading to enhanced crop growth and productivity upto 60%.