Optimizing soil core fine root collection and characterization: significant time reduction with a sub-sampling approach

Background and aims The quantification of plant roots from soil represents a pivotal step in many studies in plant ecology and soil science. However, the substantial time investment required for this process often represents a considerable impediment to research progress. The objective of this study is to evaluate and propose a time-saving method to minimize the time required for collecting roots without compromising data integrity compared to traditional approaches. Methods The proposed Sub-sample Approach (SA) requires collecting fine roots from a sub-sample and subsequently leading calculations to estimate total root traits (mass, length, and length distribution among diameters) within the sampled soil core. A comparative analysis was carried out on root harvesting time between meticulous sample cleaning (Conventional Approach, CA) and SA. Moreover, these methods were assessed across different sites including grassland, oak forest, and olive orchard. Results The analysis conducted across many sites resulted in high heterogeneity of processing time when employing the CA (ranging from 2.6 to 27.6 h per sample). Conversely, the adoption of SA reduced processing time and resulted in less variation between samples (ranging from 37 to 112 min per sample). Remarkably, root trait data obtained using SA showed similarity to those obtained through the CA. Conclusion The SA offers a remarkable advantage over the CA by significantly reducing the time needed for root collection from soil core samples. Moreover, SA exhibits lower variability among different collection sites, while maintaining consistency in qualitative and quantitative data compared to the CA.