Dinámica térmica, física y química de suelo salino-sódico tratado con carbón de bajo rango: implicaciones en biomasa vegetal

Soil salinization is a major constraint to agricultural productivity in the Caribbean region of Colombia. Low-rank coals (LRC), characterized by their high humic acid content, have been proposed as amendments capable of improving the physical and chemical conditions of degraded soils; however, their influence on soil thermal conductivity, a key property governing heat flow, soil microclimate, and plant performance, remains poorly understood. This study assessed the thermal, physical, and chemical responses of saline-sodic soils in Cesar following LRC application. A field experiment was conducted using three LRC application rates: 0, 2, and 4 t ha⁻¹. Measurements included thermal conductivity, soil physical and chemical properties, and plant biomass. Based on the results, LRC significantly decreased soil thermal conductivity by 36%, from 1.25 to 0.60 W m-1 K-1 (P<0.05), while increasing organic matter, aggregate stability, and porosity. Significant reductions (P<0.05) were also observed in pH, electrical conductivity, sodium adsorption ratio (SAR), exchangeable sodium percentage (ESP), and cation exchange capacity (CEC). Plant biomass increased by 200%, from 1 g to 9 g (P<0.05), indicating a strong positive response under saline-sodic conditions. Correlation analyses indicated a negative association between aggregate content and thermal conductivity and a positive association between bulk density and thermal conductivity. Overall, the results suggest that LRC improves soil physical and chemical conditions while modifying thermal behavior to enhance plant growth. This study provides evidence that LRC is an effective amendment capable of improving soil functionality and strengthening agricultural resilience in vulnerable regions.