Linking Polymer Transformation and Soil Microclimate to Mulch (Bio)Degradation: A Field-Based Approach Using Mesh Bags and FTIR

The degradation of mulch materials in perennial cropping systems is governed by both polymer properties and environmental conditions. Their relative influence under field conditions remains unclear. To our knowledge, this study is one of the first to integrate mass loss measurements, polymer characterization, and soil microclimatic assessment under field conditions. A one-year field experiment was conducted under irrigated Mediterranean conditions to compare the degradation of Kraft® paper and polybutylene adipate terephthalate (PBAT)-based (Kritifil®) mulch with polypropylene (PP) geotextile fabric and polyethylene (PE) mulch in randomized blocks, with three replicates. Mass loss was quantified in situ using mesh bags, while soil moisture, temperature, and electrical conductivity (EC) were monitored monthly to characterize microclimatic and edaphic conditions underlying mulch treatments. Polymer changes were assessed by ATR-FTIR analysis of field-exposed mulch fragments. Kraft® paper degraded rapidly (≈72% mass loss), consistent with moisture-driven biological processes and susceptibility to hydrolysis. In contrast, PBAT-based mulch showed limited degradation (≈3.5%) despite favourable conditions, suggesting constraints in enzymatic activity. No mass loss was observed for PE- and PP-based mulch. ATR-FTIR analysis indicated minimal structural changes in PBAT, PP, and PE, reflecting their high stability. Overall, polymer composition and inherent (bio)degradability, rather than soil thermal time, were the main drivers of mulch (bio)degradation under Mediterranean conditions.