Permanganate Oxidizable Carbon, New Soil Health Indicator for Mollisols of the Southeastern Argentinean Pampas?

Abstract

Sustainable agriculture requires frequent soil health monitoring. Sensitive, simple, and cheap soil health indicators (SHI) are needed. This work aimed to evaluate permanganate oxidizable carbon (POXC) as SHI through analyzing 1) the magnitude of POXC change due to soil use, as compared to total (SOC) and particulate (POC) organic carbon, and hot-water extractable carbon (HWC), and 2) the relationship between POXC and SOC, POC, HWC, anaerobically mineralized nitrogen (AN), and aggregate stability (AS). Soil samples (0–5 and 5–20 cm) from 32 crop production fields (CPF) and pseudo-pristine areas (PPA) from Mollisols throughout the Southeastern Argentinean Pampas were analyzed: bulk density (BD), change of aggregate mean weight diameter (ΔMWD), SOC, POC, HWC, AN, and POXC. The POXC was negatively related to BD and ΔMWD, and positively, to SOC, POC, HWC, and AN. At 0–20 cm, POXC dropped 22% in CPF respect to PPA, whereas POC, AN, HWC, and SOC decreased 62%, 44%, 35%, and 25%, respectively. The POXC could be used as an SHI, given it was sensitive to the changes produced by cropping and it related to other soil properties that indicate soil health status. Its determination is simple, fast, and cheap, which favors its adoption by soil test laboratories.