Is Permanganate Oxidizable Soil Carbon a Good Indicator of Mineralizable Soil Nitrogen?.

Soil nitrogen (N) mineralization is the transformation of organic N (e.g. proteins) into inorganic N compounds (e.g. NH₄⁺, NO₃^-), and is reportedly related to soil organic matter (SOM) and particulate organic matter (POM). Permanganate oxidizable carbon (POXC) is a relatively new method that rapidly and inexpensively quantifies labile soil C. We used the long-term aerobic incubation method to determine the potential mineralizable nitrogen (PMN) from the 0-10 cm soil depth increment across six diverse tillage and rotation systems imposed on a Maury silt loam (fine, mixed, active, mesic Typic Paleudalf), and measured POXC, SOM, and POM to determine whether POXC was a better indicator of PMN than SOM or POM. Coefficients of determination between PMN and soil organic carbon (SOC), soil organic nitrogen (SON), POXC, particulate organic carbon (POC), and particulate organic nitrogen (PON) were 0.70, 0.60, 0.55, 0.35 and 0.37, respectively. Our analysis demonstrates that SOC was a better indicator of potential mineralizable soil N than POXC, SON, or POM, while POXC could also be selected as a good practical indicator of mineralizable soil nitrogen since this measurement can be conveniently done with a field kit that used a hand-held colorimeter. 

Key terms: Permanganate Oxidizable Carbon; SOM; POM; soil N mineralization