Assessing the impact of nano-milled biochar on some soil fertility indices, microbial and enzymatic activities under drought condition in an okra cultivation trial

The agricultural sector faces challenges such as climate change, declining soil fertility, and nutrient deficiencies, all influenced by soil microbial and biochemical activities. Nanotechnology in agriculture has been used to improve nutrient delivery, crop performance, and resilience to pests, diseases, and climate change. However, the impact of biochar-derived nanoparticles on soil microbial communities and biochemical properties remains underexplored. This study applied six levels of nano-milled biochar (0 g, 100 g, 200 g, 300 g, 400 g, and a 0 g control with constant water supply) to 20 g of soil planted with okra, to assess soil chemical, microbial, and biochemical properties. These included pH, organic matter, exchangeable acidity, nutrient levels, cation exchange capacity, base saturation, and enzymatic activities. The results showed that the application of nano-milled biochar at 100g improved soil properties significantly, with organic carbon increasing by 39.46%, cation exchange capacity by 17.85%, and exchangeable calcium, potassium and magnesium by 37.06%, 34.18%, and 34.51% respectively. Nitrogen and phosphorus increased by 41.97%, and 24.33%, respectively. Additionally, it positively influenced microbial populations and enzymatic activities of enzymes, particularly urease, phosphatase, and amidase. However, at higher application, a negative effect was found on enzymatic activities. Thus, nano-milled biochar emerges as a promising soil amendment for enhancing soil health through improved microbial and biochemical activities.