Designed residue-based amendments tailored to soil-specific requirements for wheat within an integrated nutrient management framework

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Introduction Inorganic fertilizers (IF) remain the most common nutrient source in agriculture due to their high nutrient availability to crops and efficiency. Circular economy strategies through waste recovery can complement them. However, the use of wastes remains challenging because they contain multiple nutrients and potential pollutants. This study aims to demonstrate that using waste-derived soil amendments can reduce the reliance on IF. Methods We compared different treatments: (1) Control (no-fertilized); (2) formulated residue-based amendment (RBA); (3) inorganic fertilizer (IF); and (4) their combination, RBA + IF (50:50), as an integrated nutrient management (INM) strategy. Moreover, the RBAs were specifically designed for each of the four agricultural soils studied to supply equal amounts of N, P, K, and S among the treatments and formulated according to Regulation 1009/2019 (EU). The main soil constraints targeted were texture, pH, organic matter, low P and K availability, and high Mn levels of nutrient availability. Wheat performance was evaluated through germination, SPAD, total biomass, yield, plant nutrition, nutrient use, and physiological efficiency. Results One key result was the significant soil × treatment interaction found with the factorial ANOVA for most variables analyzed, indicating that RBA formulation should therefore be more soil specific. RBA showed the highest increase in yield compared to Control in Soil 1 (97%) and 4 (39%), while IF did it in Soil 2 (223%) and RBA + IF in Soil 3 (183%). Discussion We conclude that the effectiveness of RBA and RBA + IF as alternatives to IF depends on soil-specific formulation and nutrient-release dynamics.