Changes in Composition and Connectivity of Soil Nematode Assemblages under Different Mulching Systems in a Strawberry Field Experiment

Healthy soils are of pivotal importance in sustainable production of fruits and vegetables, as majority of soil functions rely on the diversity and complexity of soil food webs. A five-month field experiment was conducted under an organic strawberry production system to better understand soil food web dynamics indicated by changes in soil nematode communities after two commonly used mulch treatments (grass hay and black geotextile). In addition to the traditional methods (diversity and community indices) in nematode ecology, we applied network analysis to identify the key relationships between nematode taxa/feeding groups under different mulching systems. Soil nematodes were significantly influenced by sampling time and mulch treatments during the study period. Total density of nematodes was lower in both non-mulched and covered soils compared to pre-plant levels. Effective species number (Hill’s number) of soil nematodes was higher in plots covered with geotextile as a result of the treatment. Significant difference was observed in community composition among treatments and sampling times. Although bacterial feeders dominated in almost all samples, relative abundance of fungivores increased by the end of summer. Organic mulched soils had the highest proportion of herbivores, significantly differing from untreated plots. Soil food web analysis showed that nematode assemblages became less structured and more degraded in all soils compared to the initial conditions. However, mulch applications enhance functional diversity and connectivity of assemblages, regardless of mulch type. These changes suggest a more stable soil ecosystem with higher functional resilience and adaptive capacity which is crucial to ensure viability and sustainability of agricultural production.