Improving soybean yield and oil productivity: an integrated nutrient management approach for sustainable soybean production

The increasing demand for oilseed crops like soybeans requires sustainable cultivation practices that not only boost productivity but also maintain the long-term health of soil and the environment. This research aimed to investigate the impact of an integrated nutrient management strategy, which includes organic sources (compost types), phosphorus management, and inoculation with phosphate-solubilizing bacteria (PSB), on soybean productivity and profitability. Furthermore, the study examined the response of soybeans to varying potassium levels and different types of compost under both irrigated and dryland conditions. Two separate field experiments were conducted, with and without PSB seed inoculation, to evaluate various parameters including yield components, seed quality, protein and oil contents, grain yield, and growers' income. The results demonstrated that the application of sole poultry manure compost significantly improved yield components, grain yield (3064 kg ha^-1), protein yield (771 kg ha^-1), and oil yield (546 kg ha^-1). Application of the highest P level (90 kg P ha^-1) produced the maximum grain yield (3222 kg ha^-1), protein yield (823 kg ha^-1), and oil yield (588 kg ha^-1). Furthermore, plots treated with PSB exhibited higher yield components, grain yield (3051 kg ha^-1), protein yield (769 kg ha^-1) and oil yield (550 kg ha^-1). Moreover, increasing phosphorus levels in conjunction with poultry manure compost or a combination of poultry + cattle manure composts resulted in improved yield components, protein and oil yields, and grain yield. In another aspect of the study, the response of soybean to potassium levels and different compost types under irrigated and dryland conditions was assessed. The findings revealed that higher potassium level (90 kg K ha^-1) significantly increased yield components and produced the maximum grain yield (3189 kg ha^-1), protein yield (725 kg ha^-1), and oil yield (574 kg ha^-1). Additionally, the application of sole poultry manure compost increased all yield components, grain yield (3160 kg ha^-1), protein yield (719 kg ha^-1), and oil yield (569 kg ha^-1). Moreover, the irrigated plots demonstrated higher yield components, grain yield (2981 kg ha^-1), protein yield (680 kg ha^-1) and oil yield (536 kg ha^-1). In conclusion, this research emphasizes the significance of an integrated nutrient management approach, incorporating compost, potassium, phosphorus, and phosphate solubilizing bacteria in enhancing soybean productivity and profitability.