Soil biological responses to bio-based hydromulches formulated from different agro-industrial residues under controlled laboratory conditions

Liquid-applied mulches (hydromulches) have been proposed as a biodegradable alternative to conventional plastic mulches, with the potential to improve the sustainability of agricultural and urban systems. Although their effectiveness in weed control and soil moisture conservation has been demonstrated, there is still limited knowledge about how hydromulch composition, particularly the origin of the lignocellulosic residues used, affects their degradation and soil biological activity in the medium and long term.In this study, we assessed the effects of twelve hydromulch formulations prepared from different agricultural and agro-industrial residues of herbaceous and woody origin on soil biological quality. The experiment was conducted under controlled conditions using a 300-day microcosm incubation. Hydromulches were incorporated into agricultural soil, and key indicators of microbial activity and soil functioning were periodically measured, including soil respiration and several enzyme activities.Overall, soil biological activity increased after hydromulch application, although clear differences were observed depending on the type of residue used. Some formulations caused strong and early stimulation of microbial respiration and enzyme activity, whereas others showed more moderate but longer-lasting effects. Similarly, enzymatic activities associated with different nutrient cycles responded differently depending on hydromulch composition, reflecting distinct degradation patterns and substrate availability.These results suggest that hydromulches act not only as physical soil covers but also influence soil biological activity depending on their composition. Because microbial and enzymatic activities are closely linked to nutrient cycling, these effects may have important implications for soil fertility and soil health. Therefore, selecting specific residues for hydromulch formulation may be a useful strategy within circular bioeconomy approaches aimed at improving soil functioning.Keywords: hydromulches, soil biological activity, agro-industrial residues, soil healthAcknowledgements: PID2020-113865RR-C43 (HMulchCircle)/AEI/10.13039 - 501100011033 (Spanish Ministry of Science and Innovation) / 2024-TRAN-36705 (University of Castilla-La Mancha)