Linking anaerobic digestate application to soil microbial and nematode community structure, diversity, and functionality in maize cultivation

Conventional chemical fertilization, while effective at increasing crop yields, can pose risks to soil biota and longterm soil health. Anaerobic digestate represents a sustainable alternative, providing nutrients while potentially mitigating negative impacts on soil organisms. To evaluate this, we conducted a field experiment with maize, comparing the effects of digestate, conventional chemical fertilizer, and a mixed fertilization treatment over one growing season. Digestate supplied essential nutrients to the soil and supported plant biomass production at levels comparable to, or exceeding, those achieved with conventional fertilization. The lack of significant shifts in microbial community composition and alpha diversity suggests that digestate-associated taxa failed to colonize the soil or significantly alter the indigenous microbiome. Soil nematode communities responded to digestate by favoring bacterivorous taxa, particularly Acrobeloides, while reducing herbivorous nematodes, such as Pratylenchus. Although overall microbial functional diversity did not differ significantly between treatments, we observed treatment-specific enrichments of certain bacterial and fungal taxa, indicating functional redundancy within the soil microbiome. Overall, these results highlight the potential of anaerobic digestate as an effective and sustainable fertilizer that supports crop productivity while maintaining soil ecological integrity.