Effects of phosphorus rich organic manure (PROM) on growth and yield of soybean in calcareous soil

The phosphorus fixation and its availability are a major challenge not only in alkaline or calcareous soil but also in acidic soil. The stress of nutrient availability from soil is a major challenge for more phosphorus demanding leguminous crops like soybean. Using organic manure and rock phosphate in presence of phosphorus solubilising bacteria (PSB) plays a vital role not only by enhancing phosphorus availability but also by reducing stress of other nutrients too. The purpose of this study was to evaluate the impact of various phosphorus sources, including organic and inorganic inputs, on the growth parameters and productivity of soybean cultivated in calcareous soil conditions. The study found that applying 75% or 100% P2O5 through phosphorus rich organic manure or 100% via vermicompost significantly improved soybean growth, with larger leaves and plant height at days 28 and 56 after sowing. Phosphorus rich organic manure amendment for 100% P2O5 also resulted in the largest leaf area per plant (1,657.26 cm²), leaf area index (7.37), and total chlorophyll content (1.23 mg g⁻¹). Additionally, 100% P2O5 through phosphorus rich organic manure led to significantly more pods per plant (46.33), seeds per pod (3.00), and seeds per plant (150.27). Subsequently, significantly higher grain (25.94 q ha-1) and straw (35.16 q ha-1) yield of soybean was achieved with the application of 100% P2O5 via phosphorus rich organic manure and which was followed by incorporation of 75% P2O5 via phosphorus rich organic manure or 100% P2O5 through vermicompost. Hence this could be a sustainable way of producing P-rich organic manure to improve the growth and yield attributes of soybean. The findings of this study can be beneficial to soil scientists, agronomist, farmers and agricultural enterprises working involved in legume production and other phosphorus demanding crops