Efficacy Improvement of ZEVO (ZEzika VOlkanika) through Mineral and Organic Supplies: A Case Study of the Bean (Phaseolus vulgaris)

In Madagascar, agriculture remains largely traditional, practiced on often depleted and acidic soils, particularly ferralitic soils. This situation limits agricultural yields and undermines food security, in a context marked by the high cost and limited availability of imported chemical fertilizers. Faced with this problem, the utilization of local resources, such as volcanic scoria treated as ZEVO (ZEzika VOlkanika), represents a sustainable alternative for improving soil fertility. This study aims to evaluate the effect of ZEVO combined with manure or varying doses of mineral fertilizer on bean growth and productivity. Four treatments were compared to an unamended control (T), ZEVO + manure (Z + F), ZEVO + manure + NPK at 2.5% weight of the mixture (Z + F + NPK (2.5%)), and ZEVO + manure + NPK at 5% weight of the mixture (Z + F + NPK (5%)). The Z + F treatment yielded slightly more pods with larger seeds, while the Z + F + NPK (2.5%) treatment produced a greater number of seeds but of smaller size and lower mass. Applying a 5% dose of NPK did not improve the results, demonstrating that an excess of NPK can hinder crop development due to nutritional imbalances. The combination of ZEVO and manure already provides a balanced and effective supply of nutrients. Therefore, judicious fertilization combining natural resources with organic inputs is essential to optimize crop production.