This study aimed to evaluate the effect of soil fertility levels on the growth, chlorophyll content, and yield of soybeans at the BINA substation in Barisal. The research was conducted using Binasoybean-3 in a randomized complete block design (RCBD) with three replications. Four different soil fertility treatments were applied: F0 (no fertilizer), F1 (Rhizobium inoculation), F2 (NPK fertilizer), and F3 (Organic matter, cow dung at 2 tons ha-1). Macronutrients such as nitrogen (N), phosphorus (P), and potassium (K) were supplied through urea, triple super phosphate, and muriate of potash. Plants that did not receive any fertilizer had the lowest chlorophyll content, while plants treated with NPK showed the highest chlorophyll content, which was 21.78% higher than the control. This higher chlorophyll level in NPK-treated plants contributed to superior total dry mass (TDM) accumulation at both 80 and 90 days after sowing (DAS), with an increase of 60.83% and 81.49%, respectively, compared to the control. The maximum absolute growth rate was observed in NPK-treated plants at both 80 and 90 DAS. Furthermore, key yield-related traits, including the number of branches, pods, grains per pod, and 1000-grain weight, were highest in NPK-treated plants. As a result, the grain yield in NPK-treated plants was 97.46% higher than the control. These findings indicate the essential role of adequate NPK fertilization in maximizing soybean grain yield, as it enhances chlorophyll production, which in turn improves yield and plant growth.
