Nutrient Uptake Responses to Biochar-Based Slow Nutrient Release Fertilizer in Vertisol and Its Effect on Cotton (Gossypium spp.) Productivity

Abstract

Background: Biochar-based slow nutrient release fertilisers may provide a more gradual nutrient supply than conventional fertilisers and could support nutrient uptake in cotton. Aim: This study aimed to evaluate the efficacy of a biochar-based slow nutrient release fertiliser (SnRF, 10% N w/w) applied at varying nitrogen levels on the productivity and total NPK uptake of cotton grown in a Vertisol. Study Design: The experiment was conducted using a randomised block design (RBD) with seven treatments and three replications. Place and Duration of Study: Research Farm, Department of Soil Science, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, India, during the Kharif season of 2024–25. Methodology: The experiment involved seven treatments under the RBD, as follows: Absolute control (T1), 100% RDF through straight fertiliser (T2), 100% RDF through straight fertiliser + FYM @ 5 t   ha-1 (T3), 100% RDN through SnRF + 100% PK through straight fertiliser (T4), 75% RDN through SnRF + 100% PK through straight fertiliser (T5), 50% RDN through SnRF + 100% PK through straight fertiliser (T6), and 25% RDN through SnRF + 100% PK through straight fertiliser (T7). The cotton crop was managed with a recommended fertiliser dose (RDF) of 90:45:45 kg N, P2O5, K2O ha-1 using a spatial planting geometry of 90 cm × 45 cm. At crop maturity, economic performance was evaluated using seed cotton and stalk yields, which were subsequently correlated with total nitrogen (N), phosphorus (P), and potassium (K) uptake. Conclusion: Compared with T2, treatment T3 significantly increased seed cotton and stalk yields by 12.47% and 8.44%, respectively. Similarly, treatment T4 increased seed cotton and stalk yields by 4.78% and 2.50%, respectively, relative to T2. These productivity increases were closely reflected in macronutrient uptake; T3 increased total nitrogen (N), phosphorus (P), and potassium (K) uptake by 26%, 19%, and 15%, respectively, whereas T4 increased N, P, and K uptake by 14%, 8%, and 6%, respectively, compared with T2. Consequently, these findings indicate that inorganic fertilisers combined with FYM performed better, while slow nutrient release fertiliser (SnRF) served as an efficient and potentially sustainable alternative to conventional inorganic fertilisation.