Aggregation and soil organic carbon fractions under different land uses on the tableland of the Loess Plateau of China

Liu, Mengyun; Chang, Qingrui; Qi, Yanbing; Liu, Jing; Chen, Tao

doi:10.1016/j.catena.2013.11.002

Cited by 141 publications

(59 citation statements)

References 43 publications

(48 reference statements)

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“…SOC played a significant role in the improvement of the physicochemical properties of the soil and the formation of soil aggregates [47,48]. Our results are in line with similar findings of other researchers [49][50][51][52][53][54][55] and demonstrate that grassland contains a high amount of SOC and a significantly higher SOC content was observed in AAO. This is perhaps due to slightly higher WSA, GMD, and MWD in AAO and GL compared to the other types of land use.…”

Section: Differences In Soc Between Different Land-use Systemssupporting

confidence: 92%

Effects of Different Land-Use Systems on Soil Aggregates: A Case Study of the Loess Plateau (Northern China)

Kalhoro

Chen

et al. 2017

Sustainability

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Soil aggregate stability is an important indicator for controlling soil losses and can improve soil quality, particularly in an area such as the Loess Plateau. The objective of this study was to estimate the differences in soil aggregates across six different land-use systems (grassland, apple orchard, abandoned apple orchard, cropland maize, cropland wheat, and shrub-grassland). For this purpose, dry and wet sieving techniques were employed to assess aggregate content and aggregate stability. Higher percentages of water stable aggregates were observed in the abandoned apple orchard and shrub-grassland at 63% and 61%, respectively. The maximum dry aggregate stability (%) was recorded at 78% and 77% in both wheat cropland and common apple orchard, and the abandoned apple orchard was only 74%. Both mean weight diameters and geometric mean diameters of aggregate were recorded as higher in grassland, shrub-grassland, and the abandoned apple orchard, than the other land uses. The formation of soil aggregates and their stability were positively correlated with soil organic carbon content and root biomass of different plant communities. Higher amounts of soil organic carbon content were noted in the abandoned apple orchard, common apple orchard, and natural grassland at the 0-20 cm soil layer. The results of the correlation coefficient showed a positive significant correlation between the mean weight diameter, geometric diameter, root biomass, and soil organic carbon content. Conclusively, the type of land use affected the soil aggregation and distribution of size fractions; the small fractions of the aggregates formed large fractions by combining with fresh organic matter, and increased soil organic carbon concentrations were closely linked with the formation of macro-aggregates. Thus, converting slope farmland to forestland and grassland could improve water-stable aggregate and reduce soil disturbances in areas (like the Loess Plateau) with the highest erosion risk.

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Section: Differences In Soc Between Different Land-use Systemssupporting

confidence: 92%

Effects of Different Land-Use Systems on Soil Aggregates: A Case Study of the Loess Plateau (Northern China)

Kalhoro

Chen

et al. 2017

Sustainability

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“…In the present study, soil bulk density was mean values obtained from eight common pedo-transfer functions (Xu et al 2015). Mean weight diameter (MWD), geometric mean diameter (GMD), percentage of > 0.25 mm water stable aggregates (R 0.25 ), structure deterioration rate (SDR), index of unstable aggregates (E LT ), and stability ratio of water stable aggregate (WSAR) were calculated according to the methods described by Fan et al (2010), Gupta Choudhury et al (2014), and Liu et al (2014a). The ratios of alkyl C/O-alkyl C, aliphatic C/aromatic C, and hydrophobic C/ hydrophilic C were calculated according to the method of Zhang et al (2011).…”

Section: Calculations and Statistical Analysismentioning

confidence: 99%

“…As expected, MWD, GMD, R 0.25 , SDR, E LT and WSAR were significantly correlated with each other (Table 6). A larger MWD, GMD, R 0.25 and WSAR and a smaller SDR and E LT indicated the stability of soil aggregates was higher (Fan et al 2010;Gupta Choudhury et al 2014;Liu et al 2014a). Thus, our results (Table 3) suggested that the stability of soil water-stable aggregates was the highest for alpine meadow, followed by alpine steppe and alpine desert.…”

Section: Soil Aggregate Stabilitymentioning

confidence: 99%

Soil organic carbon contents, aggregate stability, and humic acid composition in different alpine grasslands in Qinghai-Tibet Plateau

Cao

Yong

et al. 2016

J. Mt. Sci.

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Alpine grassland soils on Qinghai-Tibet Plateau store approximately 33.5 Pg of organic carbon (C) at 0-0.75 m depth and play an important role in the global carbon cycle. We investigated soil organic C (SOC), water-soluble organic C (WSOC), easily oxidizable organic C (EOC), humic C fractions, aggregate-associated C, aggregate stability, and humic acid (HA) composition along an east-west transect across Qinghai-Tibet Plateau, and explored their spatial patterns and controlling factors. The contents of SOC, WSOC, EOC, humic C fractions and aggregate-associated C, the proportions of macroaggregates (2-0.25) and micro-aggregates (0.25-0.053 mm), and the aggregate stability indices all increased in the order alpine desert < alpine steppe < alpine meadow. The alkyl C, O-alkyl C, and aliphatic C/aromatic C ratio of HA increased as alpine desert < alpine meadow < alpine steppe, and the trends were reverse for the aromatic C and HB/HI ratio. Mean annual precipitation and aboveground biomass were significantly correlated with the contents of SOC and its fractions, the proportions of macro-and microaggregates, and the aggregate stability indices along this transect. Among all these C fractions, SOC content and aggregate stability were more closely associated with humic C and silt and clay sized C in comparison with WSOC, EOC, and macro-and microaggregate C. The results suggested that alpine meadow soils containing higher SOC exhibited high soil aggregation and aggregate stability. Mean annual precipitation should be the main climate factor controlling the spatial patterns of SOC, soil aggregation, and aggregate stability in this region. The resistant and stable C fractions rather than labile C fractions are the major determinant of SOC stocks and aggregate stability. Keywords

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“…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]. Use of density fractions and size fractions to characterize SOC from recent residue inputs shows that the nitrogen concentration and nitrogen availability of the SOC are affected by not only the fractionation method, but also by the quality and placement of the residue and by the environmental conditions that speed or slow the breakdown [49].…”

Section: Discussionmentioning

confidence: 99%

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

McGonigle

Turner

2017

Agriculture

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Primarily using cropped systems, previous studies have reported a positive linear relationship between microbial biomass carbon (MBC) and soil organic carbon (SOC). We conducted a meta-analysis to explore this relationship separately for grasslands and croplands using available literature. Studies were limited to those using fumigation-extraction for MBC for field samples. Trials were noted separately where records were distinct in space or time. Grasslands were naturally occurring, restored, or seeded. Cropping systems were typical of the temperate zone. MBC had a positive linear response to increasing SOC that was significant in both grasslands (p < 0.001; r 2 = 0.76) and croplands (p < 0.001; r 2 = 0.48). However, MBC increased 2.5-fold more steeply per unit of increasing SOC for grassland soils, as compared to the corresponding response in cropland soils. Expressing MBC as a proportion of SOC across the regression overall, slopes corresponded to 2.7% for grasslands and 1.1% for croplands. The slope of the linear relationship for grasslands was significantly (p = 0.0013) steeper than for croplands. The difference between the two systems is possibly caused by a greater proportion of SOC in grasslands being active rather than passive, relative to that in croplands, with that active fraction promoting the formation of MBC.

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Aggregation and soil organic carbon fractions under different land uses on the tableland of the Loess Plateau of China

Cited by 141 publications

References 43 publications

Effects of Different Land-Use Systems on Soil Aggregates: A Case Study of the Loess Plateau (Northern China)

Effects of Different Land-Use Systems on Soil Aggregates: A Case Study of the Loess Plateau (Northern China)

Soil organic carbon contents, aggregate stability, and humic acid composition in different alpine grasslands in Qinghai-Tibet Plateau

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

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