Microbiological parameters as indicators of soil organic carbon dynamics in relation to different land use management

Abstract

Labile C fractions: microbial biomass C (MBC), K 2 SO 4 extractable C (C K 2 SO 4 ) and the cumulated mineralized C in 21 days incubation at 28°C (C-CO 2(21d) ), were compared as land use indicators in a calcareous soil under three different management systems: native Querqus ilex forest (under and outside tree cover), a Pinus halepensis plantation, and cropped land (with cereals). Microbial biomass and activity were found to be low and coincided with high carbonate contents. As indicators of land use, C K 2 SO 4 and C-CO 2(21d) showed the same sensitivity as MBC. C-CO 2 emissions were measured in an incubation experiment in order to study C mineralization kinetics. The data for cumulative amounts of C-CO 2 released showed a good fit (R 2 [ 0.94) to the first-order kinetic model C m = C o (1 -e -kt ). The kinetic parameters C o and C o k were affected by land use and especially by tree cover. Principal components analysis was applied to the data and the relationship among microbial metabolic quotient (qCO 2 ), labile C pools, and MBC revealed a decrease in efficiency of organic substrate utilization with an increase in availability and lability of the organic matter.

Carbon content of forest floor and mineral soil in Mediterranean Pinus spp. and Oak stands in acid soils in Northern Spain

“…In contrast, in Pinus spp., clay contents didn´t show significant differences between depths probably due to mixing of soil horizons when the afforestation was performed. The higher clay contents found in the second depth in oak stands could explain the higher values (Anderson, 2003;Llorente & Turrión, 2010). In principle, the qCO 2 values were expected to decrease with increasing substrate quality being higher under unfavourable than under favourable conditions.…”

Carbon, nitrogen and organic C fractions in topsoil affected by conversion from silvopastoral to different land use systems

“…However, the area cultivated over the past 50 years under continuous arable land presented similar C MB values compared with SP and SP-GL. C MB corresponds to a small portion of TOC, which has been shown to be more sensitive to provide indications of changes and future trends in SOM caused by modified management practices (Llorente and Turrión 2009;Maia et al 2007;Sparling 1997). Contrasting these findings, Hungria et al (2009) Vertical bars represent the standard error (n = 3).…”

“…Microbial biomass is defined as the living component of SOM (Sparling 1997), which is strongly influenced by environmental factors including soil moisture and temperature (Post and Kwon 2000). C MB corresponds to a small portion of TOC, which has been shown to be more sensitive to provide indications of changes and future trends in SOM caused by land use conversion (Llorente and Turrión 2009;Maia et al 2007;Sparling 1997). For that reason, the study of different C fractions, are useful tools to assess changes caused by different land use systems.…”

Effect of Cultivation on Organic Carbon Pools and Nutrient Availability in Soil under Different Land Use System: A Review

“…Microbial biomass carbon (MBC) corresponds to a small portion of total organic carbon and is sensitive to variations in land-use and soil management practices which provide indications of changes and future trends in SOM caused by modified management practices (Llorente and Turrion, 2009). Land use/land cover changes (degradation of natural forest and subsequent cultivation of soils) resulted in significant decreases in microbial biomass (Islam et al, 2000).…”