Comparison of Permanganate‐Oxidizable Carbon and Mineralizable Carbon for Assessment of Organic Matter Stabilization and Mineralization

Abstract

Permanganate-oxidizable C (POXC) and mineralizable C (as determined by short-term aerobic incubation of rewetted soil) are measures of active organic matter that may provide early indication of soil C stabilization and mineralization processes. To date, the relationship between these two promising active organic matter tests has not been comprehensively evaluated, and little is known about their functional role in the soil ecosystem. Here, we examined the relationship between POXC and mineralizable C across a wide range of soil types, management histories, and geographic locations across the United states (13 studies, 76 total sites; n = 1071) and the ability of POXC and mineralizable C to predict crop yield and total aboveground biomass. Results from this comparative analysis showed that POXC and mineralizable C are related (r 2 = 0.15-0.80) but that the relationship was differentially influenced by management practices. Overall, POXC better reflected practices that promote organic matter accumulation or stabilization and therefore can be a useful indicator of long-term soil C sequestration. Conversely, mineralizable C better reflected practices that promote organic matter mineralization and therefore can be a useful indicator of short-term soil nutrient availability. Our results also show that both mineralizable C and POXC were better predictors of corn (Zea mays L.) grain yield, aboveground biomass, and tomato (solanum lycopersicum L.) fruit yield than other soil C fractions evaluated here. Thus, the integrated use of POXC and mineralizable C can provide a complementary framework to assess the relative dynamics of soil C stabilization and nutrient mineralization functions in agroecosystems. O f the three pools that constitute soil organic matter (SOM), the active or labile pool is comprised of rapidly cycling organic material that mostly turns over in a shorter time frame (days to a few years) relative to the intermediate (a few years to decades) and stable (decades to centuries) pools (Cambardella and Elliott, 1992;Gregorich et al., 1994;Parton et al., 1987;Wander, 2004 Core Ideas• POXC and mineralizable C were evaluated across diverse agroecosystems.• The two are related but differentially influenced by management practices.• POXC better reflected sOM stabilizing practices.• Mineralizable C reflected sOM mineralizing practices.• Both predicted agronomic performance better than other soil C fractions.

Biological P cycling is influenced by the form of P fertilizer in an Oxisol

“…This is in agreement with evidence that SOM accrual in weathered soils is strongly limited by nutrient scarcity (Kirkby et al 2013). Increases in permanganateoxidizable C and a trend toward greater SOC with P fertilization are consistent with evidence that permanganateoxidizable C can be an early indicator of SOM accrual (Lucas and Weil 2012;Weil et al 2003) and is associated with management practices that promote SOM stabilization (Hurisso et al 2016). …”

Soil Organic Carbon Pools as Early Indicators for Soil Organic Matter Stock Changes under Different Tillage Practices in Inland Pacific Northwest

“…These results are in accordance with those reported by Morrow et al (2016), who observed that POXC, WEOC, WEON, MBC, MBN,, N-mineralization, acid hydrolysable, and non-hydrolysable C-and -N, SOC, and TN were all positively correlated with each other across soils under diverse agroecosystems within the iPNW. Similarly, significant interrelationships among SOM pools have also been reported in other arable soils in different agroecoregions (Cookson et al, 2008;Dou et al, 2008;Chen et al, 2009;Culman et al, 2012;Awale et al, 2013;Hurisso et al, 2016). Nevertheless, in the present study, C-pools were more strongly correlated with SOM compared to N-pools.…”

“…The POXC fraction of SOC is characterized based on its susceptibility to oxidation with weak potassium permanganate (KMnO 4 ) solution, and thereby simulates microbial oxidation (Weil et al, 2003). According to Culman et al (2012) and Hurisso et al (2016), POXC reflects a more stabilized fraction of SOC and reduced tillage promotes POXC in soils compared to intensive tillage because the latter increases microbial oxidation of POXC. High correlations of POXC with MBC (r = 0.76) and with microbial activity (r = 0.67) corroborate this assertion.…”

“…Basal respiration (BR) and C-mineralization are adequate indicators of microbial activity, which is dependent on substrate availability and the soil edaphic environment (Balota et al, 2003). A build-up of POXC in soil indicates long-term SOM stabilization (Culman et al, 2012(Culman et al, , 2013Hurisso et al, 2016). To this end, analyzing SOM pools and characterizing their interrelationships could improve our understanding of management effects on SOM dynamics in the iPNW.…”

Grasslands and Croplands Have Different Microbial Biomass Carbon Levels per Unit of Soil Organic Carbon

“…Chemical estimation of the active fraction of SOC has used permanganate oxidation [45], and this method has been applied to soil quality evaluation [46]. However, recent work illustrates that the fraction of SOC determined by permanganate appears to contribute primarily to SOC sequestration, whereas a closer correspondence to nutrient availability in the short term is shown by the SOC fraction disposed to mineralization during incubation studies [47]. Similarly, the fraction of SOC oxidized with dichromate was associated with larger aggregates of grassland and forest, rather than the small aggregates of croplands [48].…”