ESTIMATING SOIL PARTICULATE ORGANIC CARBON THROUGH TOTAL SOIL ORGANIC CARBON

Resumen

Particulate soil organic carbon (POC) is sensitive to management changes, and a good soil health indicator. However, its determination is tedious and time consuming. Given POC changes represent most of total organic carbon (TOC) variation due to soil use, we hypothesized that POC can be estimated through the variation of TOC. Our objective was to evaluate changes of POC and TOC for a wide range of soil silt (Si) + clay (Cy) contents to assess the feasibility of estimating POC through TOC. Soil samples (n=161) were collected from the surface layer of fields under no tillage throughout the Argentinean Pampean Region, and their TOC and POC were determined. The variation of POC was described with exponential models fitted as a function of both TOC and TOC/(Si+Cy). The models fitted adequately estimated POC as a function of TOC (R²=0,96, observed vs estimated not different form 1:1 line). No improvement was observed when POC and TOC contents were relativized to Si+Cy contents (R²=0,97). Approximately 74% of the estimated values of POC deviated less than ±10% from the observed. We conclude that for the conditions studied, the model acceptably estimated POC knowing TOC hence saving time and resources to assess soil health status.