An appraisal of soil organic C content in Mediterranean agricultural soils

2011 ◽  
pp. no-no ◽  
Author(s):  
J. Romanyà ◽  
P. Rovira
Keyword(s):  
Agricultural Soils ◽  
Soil Organic C ◽  
Organic C

Soil carbon sequestration and density distribution in a Vertosol under different farming practices

Soil Research ◽  
2004 ◽  
Vol 42 (8) ◽  
pp. 875 ◽  
Author(s):  
W. J. Wang ◽  
R. C. Dalal ◽  
P. W. Moody
Keyword(s):  
Seasonal Variations ◽  
Agricultural Soils ◽  
Cropping System ◽  
Subtropical Climate ◽  
Soil Organic C ◽  
Farming Practices ◽  
Winter Cereal ◽  
Organic C ◽  
Fallow Period

Abstract Agricultural soils play an important role in the global carbon (C) cycling and can act as a significant C sink if managed properly. The long-term (33 years) effects of no till (NT) v. conventional till (CT), stubble retention (SR) v. stubble burning (SB), and N fertiliser application (NF) v. nil N fertilisation (N0) on soil organic C sequestration, and their seasonal variations during the fallow period, were studied in a winter cereal–summer fallow cropping system under semi-arid subtropical climate in Queensland, Australia. The function of different density fractions of soil organic C in determining total organic C (TOC) dynamics and sequestration was investigated. Significant effect of NT, SR, or NF on soil organic C level was observed only in the top 10 cm soil and when they were practiced together, with the TOC contents being 1.1 to 3.4 t/ha higher under NT + NF + SR than under other treatments. There were significant seasonal fluctuations in TOC contents at different stages of the fallow period, and the lowest levels of TOC and treatment effects were observed in the late fallow period. Density fractionation of soil organic C showed that light fraction C (<1.6 g/cm3) declined rapidly during the fallow period and did not accumulate substantially in soil. TOC dynamics, either as a consequence of seasonal variations or as a long-term response to different farming practices, were predominantly controlled by the changes in the heavy fraction C (>1.6 g/cm3).

Comparison of structural stability, carbon fractions and chemistry of krasnozem soils from adjacent forest and pasture areas in south-western Victoria

Soil Research ◽  
2002 ◽  
Vol 40 (2) ◽  
pp. 283 ◽  
Author(s):  
M. R. Carter ◽  
J. O. Skjemstad ◽  
R. J. MacEwan
Keyword(s):  
Nmr Spectroscopy ◽  
Structural Stability ◽  
Forest Soils ◽  
Agricultural Soils ◽  
13C Nmr Spectroscopy ◽  
Soil Organic C ◽  
Organic C ◽  
Photo Oxidation ◽  
Western Victoria

Basalt-derived krasnozems are generally well-structured soils; however, there is a concern that intensive agricultural practices may result in an adverse decline in soil organic carbon, organic matter chemistry, and structural quality over time. A study was conducted on loam to silty clay loam krasnozems (Ferrosols) near Ballarat in south-western Victoria to assess changes in soil C, soil structural stability, and C chemistry, at the 0–10 cm soil depth, under 3 paired sites consisting of adjacent long-term forest (Monterey pine or eucalyptus) v. 30 year cropping &lsqb;3 year pasture–2 year crops (potato and a root crop or grain)&rsqb;. Soil structural stability was also characterised in the A and B horizons under long-term eucalyptus and several cropped sites. Organic C levels in the A horizons for all the soils were relatively high, ranging from 46 to 89 g&sol;kg. A lower organic C (30&percnt;), associated mainly with loss of the sand-sized (&gt;53 m) macro-C fraction, and a decrease in exchangeable Ca and Mg was found in the agricultural soils, compared with forest soils. Physically protected C in the &lt;53 m fraction, as indicated by UV photo-oxidation, was similar among soils. Wet sieving indicated a decline of both C and N concentration in water-stable aggregates and the degree of macro-aggregation under agricultural soils, compared with the forest soils. However, soil structural changes under cropping were mainly related to a decline in the &gt;5 mm sized aggregates, with no deleterious increase in the proportion of 0.10 mm aggregates. Solid state 13C NMR spectroscopy indicated a decrease in O-alkyl and alkyl C under pasture and cropping compared with forest soils, which was in agreement with the decline in the macro-C fraction. Characterisation of C chemistry following UV photo-oxidation showed that charcoal C (dominant presence of aryl C) accounted for 30&percnt; of the total soil organic C, while other functional groups (polysaccharides and alkyl C) were probably protected within micro-aggregates. Based on soil organic C and aggregate stability determinations alone, the implications for soil physical quality, soil loss, and diffuse pollution appear minimal. macroorganic carbon, soil aggregation, charcoal, photo-oxidation, potato rotation, CP&sol;MAS 13C NMR spectroscopy.

scholarly journals Estimations of soil fertility in physically degraded agricultural soils through selective accounting of fine earth and gravel fractions

Solid Earth ◽  
2016 ◽  
Vol 7 (3) ◽  
pp. 897-903 ◽  
Author(s):  
Mavinakoppa S. Nagaraja ◽  
Ajay Kumar Bhardwaj ◽  
G. V. Prabhakara Reddy ◽  
Chilakunda A. Srinivasamurthy ◽  
Sandeep Kumar
Keyword(s):  
Soil Fertility ◽  
Bulk Density ◽  
Agricultural Soils ◽  
Land Development ◽  
Soil Mass ◽  
Available Phosphorus ◽  
Soil Organic C ◽  
Fine Earth ◽  
Degraded Lands ◽  
Organic C

Abstract. Soil fertility and organic carbon (C) stock estimations are crucial to soil management, especially that of degraded soils, for productive agricultural use and in soil C sequestration studies. Currently, estimations based on generalized soil mass (hectare furrow basis) or bulk density are used which may be suitable for normal agricultural soils, but not for degraded soils. In this study, soil organic C, available nitrogen (N), available phosphorus (P2O5) and available potassium (K2O), and their stocks were estimated using three methods: (i) generalized soil mass (GSM, 2 million kg ha−1 furrow soil), (ii) bulk-density-based soil mass (BDSM) and (iii) the proportion of fine earth volume (FEV) method, for soils sampled from physically degraded lands in the eastern dry zone of Karnataka State in India. Comparative analyses using these methods revealed that the soil organic C, N, P2O and K2O stocks determined by using BDSM were higher than those determined by the GSM method. The soil organic C values were the lowest in the FEV method. The GSM method overestimated soil organic C, N, P2O and K2O by 9.3–72.1, 9.5–72.3, 7.1–66.6 and 9.2–72.3 %, respectively, compared to FEV-based estimations for physically degraded soils. The differences among the three methods of estimation were lower in soils with low gravel content and increased with an increase in gravel volume. There was overestimation of soil organic C and soil fertility with GSM and BDSM methods. A reassessment of methods of estimation was, therefore, attempted to provide fair estimates for land development projects in degraded lands.

scholarly journals Novel Proximal Sensing for Monitoring Soil Organic C Stocks and Condition

2017 ◽  
Vol 51 (10) ◽  
pp. 5630-5641 ◽  
Author(s):  
Raphael A. Viscarra Rossel ◽  
Craig R. Lobsey ◽  
Chris Sharman ◽  
Paul Flick ◽  
Gordon McLachlan
Keyword(s):  
Soil Organic C ◽  
Proximal Sensing ◽  
Organic C ◽  
C Stocks

scholarly journals Casting Activity ofScherotheca gigasin No-Till Mediterranean Soils: Role in Organic Matter Incorporation and Influence of Aridity

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Paloma Bescansa ◽  
Iñigo Virto ◽  
Oihane Fernández-Ugalde ◽  
María José Imaz ◽  
Alberto Enrique
Keyword(s):  
Organic Matter ◽  
Agricultural Soils ◽  
Nw Spain ◽  
Organic C ◽  
No Till ◽  
Physico Chemical ◽  
C Stocks ◽  
Casting Activity ◽  
Total Organic C

The behaviour of earthworms, their role in organic matter incorporation into the soil, and the influence of aridity in such processes in arid and semiarid regions have scarcely been studied. In this study, physico-chemical analyses of the casts and the surrounding no-till agricultural soils of three experimental sites representing an aridity gradient in Navarre (NW Spain) were done. The casts were formed by the activity of the only anecic species,Scherotheca gigas(Dugès, 1828), ubiquitous in no-till soils in this region. We observed a significant depletion of clay and higher concentration of total organic C and labile C in the form of particulate organic matter (POM) in the casts as compared to the surrounding soil, suggesting selective ingestion of soil byS. gigas. This, together with the observation of increased concentration in POM with increasing aridity, suggests a major role of this species in the observed progressive gains of organic C stocks in no-till soils in the region.

Warming increases soil carbon input in a Sibiraea angustata-dominated alpine shrub ecosystem

2021 ◽  
Author(s):  
Mei Liu ◽  
Jia-Hao Wen ◽  
Ya-Mei Chen ◽  
Wen-Juan Xu ◽  
Qiong Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Root Exudates ◽  
Climate Warming ◽  
Root Exudate ◽  
Soil Organic C ◽  
Organic C ◽  
Root Litter ◽  
C Stocks ◽  
Alpine Shrub ◽  
Key Drivers

Abstract Aims Plant-derived carbon (C) inputs via foliar litter, root litter and root exudates are key drivers of soil organic C stocks. However, the responses of these three input pathways to climate warming have rarely been studied in alpine shrublands. Methods By employing a three-year warming experiment (increased by1.3 ℃), we investigated the effects of warming on the relative C contributions from foliar litter, root litter and root exudates from Sibiraea angustata, a dominant shrub species in an alpine shrubland on the eastern Qinghai-Tibetan Plateau. Important Findings The soil organic C inputs from foliar litter, root litter and root exudates were 77.45, 90.58 and 26.94 g C m -2, respectively. Warming only slightly increased the soil organic C inputs from foliar litter and root litter by 8.04 and 11.13 g C m -2, but significantly increased the root exudate C input by 15.40 g C m -2. Warming significantly increased the relative C contributions of root exudates to total C inputs by 4.6% but slightly decreased those of foliar litter and root litter by 2.5% and 2.1%, respectively. Our results highlight that climate warming may stimulate plant-derived C inputs into soils mainly through root exudates rather than litter in alpine shrublands on the Qinghai-Tibetan Plateau.

Impact of long-term cultivation on the status of organic matter and cadmium in soil

2001 ◽  
Vol 81 (3) ◽  
pp. 349-355 ◽  
Author(s):  
D. F. E. McArthur ◽  
P M Huang ◽  
L M Kozak
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Significant Positive Correlation ◽  
Soil Organic C ◽  
Organic C ◽  
Total Soil ◽  
Total Organic C ◽  
Soil Cd ◽  
Cultivated Soils

Research has suggested a link between the bioavailability of soil Cd and total soil organic matter. However, some research suggested a negative relationship between total soil organic matter and bioavailable soil Cd while other research suggested a positive relationship. This study investigated the relationship between soil Cd and both the quantity and quality of soil organic matter as influenced by long-term cultivation. Two Orthic Chernozemic surface soil samples, one from a virgin prairie and the other from an adjacent cultivated prairie, were collected from each of 12 different sites throughout southern Saskatchewan, Canada. The samples were analyzed for total organic C, total Cd, Cd availability index (CAI), and pH. The nature of the soil organic matter was investigated with 13C Cross Polarization Magic Angle Spinning Nuclear Magnetic Resonance spectroscopy (13C CPMAS NMR). The total soil Cd, CAI, and total soil organic C of the cultivated soils were significantly lower than those of the virgin soils whereas the opposite trend was observed for the soil pH and the aromaticity of the organic C. The reduced CAI in the cultivated soils was related to the increase in both the soil pH and the aromaticity of the organic C. No relationship was found between the CAI and the soil organic C content, but a significant positive correlation was found between total organic C and total Cd in both the virgin and the cultivated soils. As well, a significant positive correlation was found between the fraction of total Cd removed from the soil after long-term cultivation and the corresponding fraction of organic C removed. Key words: Long-term cultivation, soil organic matter, 13C CPMAS NMR, cadmium

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