RESIDUAL EFFECT OF BIOCHAR WITH REDUCED DOSES OF CHEMICAL FERTILIZERS ON THE SOIL PROPERTIES, GROWTH AND YIELD RESPONSE OF OKRA

Abstract

The research work was conducted in the research field of the Department of Soil Science, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur during November 2022 to January 2023 to study the residual effect of biochar with reduced doses of chemical fertilizers on the soil properties, growth and yield response of okra (Local variety: Heera). The experimental soil belongs to the Old Himalayan Piedmont Plain (AEZ-1). The experiment was laid out in the randomized complete block design (RCBD) having eleven (11) treatments with three replications. The treatments were T1 = No residual biochar + No chemical fertilizer (Control), T2 = 100% RDF (Recommended Dose of Fertilizers), T3 = 50% RDF + Residual 20 t ha-1 Rice Husk biochar, T4 = 50% RDF + Residual 20 t ha-1 Sawdust biochar, T5 = 50% RDF + Residual 20 t ha-1 Biochar enriched organic fertilizer (OF), T6 = 75% RDF + Residual 15 t ha-1 Rice Husk biochar, T7 = 75 % RDF + Residual 15 t ha-1 Sawdust biochar, T8 = 75% RDF + Residual 15 t ha-1 Biochar enriched organic fertilizer (OF), T9 = 100% RDF + Residual 10 t ha-1 Rice Husk biochar, T10 = 100% RDF + Residual 10 t ha-1 Sawdust biochar, T11 = 100% RDF + Residual 10 t ha-1 Biochar enriched organic fertilizer (OF). The results showed that the growth and yield attributing components such as plant height, number of fruit plant-1, marketable fruit weight plant-1, fruit weight plot-1, fruit length, fresh shoot biomass plant-1, dry shoot biomass plant-1, root length, fresh root weight, dry root weight responded significantly except fruit breadth due to the application of different level of chemical fertilizers along with different level of residual biochar combination. The highest values of different parameters such as plant height (74.2 cm), number of fruit plant-1 (16.6), marketable fruit weight plant-1 (197.8 g), fruit weight plot-1 (1.18 kg), fruit length (11.3 cm), fruit breadth (5.0 cm), fresh shoot biomass plant-1 (181.5 g), dry shoot biomass plant-1 (30.8 g) were obtained in T11 treatment where 100% RDF + Residual 10 t ha-1 Biochar enriched organic fertilizer (OF) were applied. The lowest results were found in the control treatment (T1). In post- harvest soil, the treatments (T4 and T5) receiving high amount (20 t ha-1) of biochar gave the highest amount of total N, available P, exchangeable K, available S, organic carbon (OC) and organic matter (OM). In case of pH the highest (7.31) was found in T5 treatment. The residual effect of biochar with reduced doses of chemical fertilizers might be better for sustainable soil health for growing crops. Overall, the results suggested that reduced doses of chemical fertilizers in previous biochar incorporated field can be better for cultivation of okra in respect to higher yield response and might be advantageous cultivation of crops in the next year.