Evaluation of Vermicompost from Local Substrates: Effects on Soil Conditioning, Nutrient Dynamics, and its Potential as a Sustainable Organic Fertilizer

This study evaluated the potential of vermiculture in improving soil fertility through the production of vermicasts derived from different organic substrates. The research focused on analyzing the chemical properties of vermicasts, particularly nitrogen (N), phosphorus (P), potassium (K), and soil pH, which are critical in determining soil quality and crop productivity. The experiment took place at Isabela State University – San Mariano Campus, San Mariano, Isabela. A Randomized Complete Block Design (RCBD) was employed with six substrate treatments: cow manure + rice straw + taro, cow manure + corn stover + taro, cow manure + ipil-ipil + taro, cow manure + centrosema + taro, cow manure + taro, and cow manure + kakawate + taro. Substrates were prepared and placed in vermibeds, and vermiworms were introduced after 15 days to initiate decomposition. Moisture was carefully maintained to ensure optimal microbial and earthworm activity. Laboratory analysis revealed that nitrogen levels were highest in vermicasts from cow manure + centrosema + taro (1.75%), indicating the positive contribution of nitrogen-fixing legumes. Treatments with rice straw and ipil-ipil also produced relatively high nitrogen contents (1.52% and 1.50%, respectively), while the lowest level was observed in cow manure + taro (1.13%). Phosphorus enrichment was likewise most pronounced in treatments with centrosema, while potassium levels peaked in combinations containing kakawate, highlighting its potential in supporting plant health and yield. Soil pH across treatments ranged from 6.94 to 7.20, reflecting a slightly acidic to neutral balance favorable for both earthworm activity and crop production. Moisture content varied widely, from 13.5% to 55%, with the highest recorded in cow manure + corn stover + taro, which created conditions conducive to nutrient transformation. Overall, the findings confirm that vermiculture is an effective means of producing a sustainable and nutrient-rich organic fertilizer. The study demonstrates that substrate composition significantly influences the nutrient profile of vermicasts, with legumes and potassium-rich plants offering particular benefits. The results emphasize the value of vermiculture as an eco-friendly alternative that improves soil health, enhances crop productivity, and contributes to long-term sustainable agricultural systems. Key words: Vermicomposting, Vermicast, Soil fertility, Nitrogen enrichment, Phosphorus dynamics, Potassium availability