Reuse of sediments from surface reservoirs for agricultural production in the Brazilian semiarid region: extraction conditions, spatio-temporal variability, financial analysis and regulatory barriers

PurposeThis study explores sediment reuse from surface water reservoirs as a soil conditioner to reduce reliance on chemical fertilizers. It considers the variability of sediment properties, the financial and environmental benefits and the regulatory barriers for adopting this practice, highlighting its potential for sustainable agricultural production.MethodsTo assess the conditions for sediment extraction in the study area, we analyzed the temporal dynamics of water storage in 19 reservoirs. Spatio-temporal characterization of sediments was conducted using a database of over 200 samples from 10 reservoirs located in the Jaguaribe River Basin, in the Brazilian semiarid region. We also performed a cost-benefit analysis of sediment reuse in the context of the latest global economic crisis.ResultsThe temporal dynamics of reservoir water storage indicate frequent and prolonged sediment exposure, enabling removal by excavation. Sediment reuse can currently result in savings of up to 68% compared to conventional fertilization. Sediment heavy metals analysis showed that copper and zinc concentrations are, respectively, 4 and 35 times lower than the limits established by the most restrictive existing legislation. Replacing chemical nitrogen fertilizers with sediment could prevent nearly 12 x 10(3) t CO(2)e emissions.ConclusionsSediment reuse in agriculture can enhance crop yields and has the potential to substantially benefit both the environment and society. However, the spatiotemporal variability of the sediment's physicochemical properties may pose a challenge to scaling up this practice. While chemical fertilizer prices fluctuate, especially during global crises, sediment reuse costs remain more stable, providing financial predictability for the agricultural sector.