Nitrogen-fortified nanobiochar impacts soil properties, root growth and basmati rice yield

Abstract Nanobiochar (NB) has emerged as a promising sustainable soil amendment, enhancing soil fertility due to its high surface area, porous nature, and nutrient retention and slow-release capabilities. Fortified nanobiochar application could be a durable strategy for enhancing soil fertility and crop productivity in nutrient deficient soils. This study investigates the effects of nitrogen-fortified nanobiochar (NBN) on nitrogen-deficient soils, aiming to reduce reliance on mineral fertilizers (MF) without compromising crop yield. An experiment was conducted with twelve treatments including MF at 100%, 75% and 50% of the recommended nitrogen dose alongside NBN applied at rates of 1,2.5 and 5 kgha −1 ), either alone or in combination. Results indicated that the combined application of 75% mineral nitrogen (N 75 ) and 5 kg ha −1 of NBN (N 75 NBN 5 ) significantly improved soil moisture content (SM), infiltration rate (IR), aggregate stability (AS) and hydraulic conductivity (H c ) by 1.01 to 1.42 times compared to the N 100 and N 75 treatments. Additionally, soil organic carbon, available N, NH 4 and NO 3 contents increased by 1.22, 1.03, 1.06 and 1.06 times, respectively, under N 75 NBN 5 over N 100 leading to enhanced nutrient uptake. Root growth metrics (root weight, length and volume) increased by 24.6%, 15.8% and 18.7%, respectively, while rice yield improved by 26.8% with N 75 NBN 5 compared to the N 75 treatment, with the lowest yield observed in the NBN 1 treatment. The significant and positive correlation between grain yield and soil physical properties and soil nutrient levels, confirmed the beneficial impact of NBN on soil properties that directly influenced crop yield. The study demonstrates that the integration of N 75 with NBN 5 not only enhances soil properties and crop growth but also offers ecological benefits by the valorization of agricultural waste into an effective soil amendment, thereby promoting sustainable agricultural practices. Graphical Abstract