Biofilm Treated Eppawala Rock Phosphate and Feldspar as Substitutes for Triple Super Phosphate and Muriate of Potash in Rice (<em>Oryza sativa</em> L.) Cultivation

The excessive and prolonged use of synthetic fertilizers such as Triple Super Phosphate (TSP) and Muriate of Potash (MOP), apart from Urea has led to serious environmental concerns, including soil and water pollution and the accumulation of heavy metals in agroecosystems. These issues have posed long-term risks to both ecosystem health and human well-being. This study evaluated biofilm-enriched Eppawala Rock Phosphate (BFE) and biofilm-enriched Feldspar (BFF) as bio-mineral fertilizers with biofilm biofertilizer (BFBF), proposed as a sustainable alternative to TSP and MOP. The experiment was conducted in a farmer managed paddy field using a Randomized Complete Block Design (RCBD) with three replicates, comparing BFE + BFF + BFBF practice with the current BFBF practice. Key parameters assessed included soil physicochemical properties, plant growth and yield, microbial activity, and heavy metal accumulation. Results indicated a significant (p<0.05) increase in exchangeable soil K in plots treated with the new BFBF practice, due to enhanced potassium availability with the BFF application. No statistically significant differences (p>0.05) were observed between the two practices for soil moisture, organic carbon, microbial biomass carbon, total phosphorus, total nitrogen, shoot and root dry weights, endophytic diazotroph populations, and crop yield. Furthermore, plant and soil cadmium (Cd) and iron (Fe) concentrations remained within safe limits and did not differ significantly between the two practices, indicating no adverse effects from the application of BFE and BFF. These findings suggest that biofilm-enriched P and K mineral fertilizers can effectively replace synthetic TSP and MOP without compromising rice growth, yield, or soil and plant health. The use of BFE and BFF within a BFBF system offers a promising approach for enhancing nutrient sustainability, reducing environmental impact, and supporting the transition toward organic and sustainable rice cultivation.