| 1. |
- Andrén, Olof, et al.
(författare)
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Carbon balances in US croplands during the last two decades of the twentieth century
- 2012
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 107, s. 207-225
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Tidskriftsartikel (refereegranskat)abstract
- Carbon (C) added to soil as organic matter in crop residues and carbon emitted to the atmosphere as CO(2) in soil respiration are key determinants of the C balance in cropland ecosystems. We used complete and comprehensive county-level yields and area data to estimate and analyze the spatial and temporal variability of regional and national scale residue C inputs, net primary productivity (NPP), and C stocks in US croplands from 1982 to 1997. Annual residue C inputs were highest in the North Central and Central and Northern Plains regions that comprise similar to 70% of US cropland. Average residue C inputs ranged from 1.8 (Delta States) to 3.0 (North Central region) Mg C ha(-1) year(-1), and average NPP ranged from 3.1 (Delta States) to 5.4 (Far West region) Mg C ha(-1) year(-1). Residue C inputs tended to be inversely proportional to the mean growing season temperature. A quadratic relationship incorporating the growing season mean temperature and total precipitation closely predicted the variation in residue C inputs in the North Central region and Central and Northern Plains. We analyzed the soil C balance using the crop residue database and the Introductory Carbon Balance regional Model (ICBMr). Soil C stocks (0-20 cm) on permanent cropland ranged between 3.07 and 3.1 Pg during the study period, with an average increase of similar to 4 Tg C year(-1), during the 1990s. Interannual variability in soil C stocks ranged from 0 to 20 Tg C (across a mean C stock of 3.08 +/- A 0.01 Pg) during the study period; interannual variability in residue C inputs varied between 1 and 43 Tg C (across a mean input of 220 +/- A 19 Tg). Such interannual variation has implications for national estimates of CO(2) emissions from cropland soils needed for implementation of greenhouse gas (GHG) mitigation strategies involving agriculture.
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| 2. |
- Andrén, Olof, et al.
(författare)
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How can soil monitoring networks be used to improve predictions of organic carbon pool dynamics and CO2 fluxes in agricultural soils?
- 2011
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 338, s. 247-259
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Tidskriftsartikel (refereegranskat)abstract
- As regional and continental carbon balances of terrestrial ecosystems become available, it becomes clear that the soils are the largest source of uncertainty. Repeated inventories of soil organic carbon (SOC) organized in soil monitoring networks (SMN) are being implemented in a number of countries. This paper reviews the concepts and design of SMNs in ten countries, and discusses the contribution of such networks to reducing the uncertainty of soil carbon balances. Some SMNs are designed to estimate country-specific land use or management effects on SOC stocks, while others collect soil carbon and ancillary data to provide a nationally consistent assessment of soil carbon condition across the major land-use/soil type combinations. The former use a single sampling campaign of paired sites, while for the latter both systematic (usually grid based) and stratified repeated sampling campaigns (5-10 years interval) are used with densities of one site per 10-1,040 kmA(2). For paired sites, multiple samples at each site are taken in order to allow statistical analysis, while for the single sites, composite samples are taken. In both cases, fixed depth increments together with samples for bulk density and stone content are recommended. Samples should be archived to allow for re-measurement purposes using updated techniques. Information on land management, and where possible, land use history should be systematically recorded for each site. A case study of the agricultural frontier in Brazil is presented in which land use effect factors are calculated in order to quantify the CO2 fluxes from national land use/management conversion matrices. Process-based SOC models can be run for the individual points of the SMN, provided detailed land management records are available. These studies are still rare, as most SMNs have been implemented recently or are in progress. Examples from the USA and Belgium show that uncertainties in SOC change range from 1.6-6.5 Mg C ha(-1) for the prediction of SOC stock changes on individual sites to 11.72 Mg C ha(-1) or 34% of the median SOC change for soil/land use/climate units. For national SOC monitoring, stratified sampling sites appears to be the most straightforward attribution of SOC values to units with similar soil/land use/climate conditions (i.e. a spatially implicit upscaling approach).
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| 3. |
- Bolinder, Martin, et al.
(författare)
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Compositional analysis for an unbiased measure of soil aggregation
- 2012
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Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 179-180, s. 123-131
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Tidskriftsartikel (refereegranskat)abstract
- Soil aggregation is an index of soil structure measured by mean weight diameter (MWD) or scaling factors often interpreted as fragmentation fractal dimensions (D-f). However, the MWD provides a biased estimate of soil aggregation due to spurious correlations among aggregate-size fractions and scale-dependency. The scale-invariant D-f is based on weak assumptions to allow particle counts and sensitive to the selection of the fractal domain, and may frequently exceed a value of 3, implying that D-f is a biased estimate of aggregation. Aggregation indices based on mass may be computed without bias using compositional analysis techniques. Our objective was to elaborate compositional indices of soil aggregation and to compare them to MWD and D-f using a published dataset describing the effect of 7 cropping systems on aggregation. Six aggregate-size fractions were arranged into a sequence of D-1 balances of building blocks that portray the process of soil aggregation. Isometric log-ratios (ilrs) are scale-invariant and orthogonal log contrasts or balances that possess the Euclidean geometry necessary to compute a distance between any two aggregation states, known as the Aitchison distance (A(x,y)). Close correlations (r>0.98) were observed between MWD, D-f, and the ilr when contrasting large and small aggregate sizes. Several unbiased embedded ilrs can characterize the heterogeneous nature of soil aggregates and be related to soil properties or functions. Soil bulk density and penetrater resistance were closely related to A(x,y) with reference to bare fallow. The A(x,y) is easy to implement as unbiased index of soil aggregation using standard sieving methods and may allow comparisons between studies. (C) 2012 Elsevier B.V. All rights reserved.
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| 4. |
- Bolinder, Martin, et al.
(författare)
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Effects of climatic data low-pass filtering on the ICBM temperature- and moisture-based soil biological activity factors in a cool and humid climate
- 2011
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800 .- 1872-7026. ; 222, s. 3050-3060
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Tidskriftsartikel (refereegranskat)abstract
- The air temperature (T-air), total precipitation (TP) and potential evapotranspiration (PET) are standard input data for soil carbon dynamic models, i.e., for calculating temperature and moisture effects on soil biological activity. The resolution needed depends on objectives, the complexity of models and inbuilt pedotransfer functions. The Introductory Carbon Balance Model (ICBM) soil climate front end model calculates a multiplicative soil-temperature (r(e_temp)) and -moisture (r(e_wat)) factor with a daily time-step to estimate soil biological activity, i.e., r(e_crop) = r(e_temp) x r(e_wat). Our objective was to determine how much re_temp. r(e_wat) and r(e_crop) are affected by low-pass filtering of the climatic input data for a cool, humid temperate region. To achieve this we conducted spectral analysis on T-air, TP, PET and r(e_crop) in the frequency domain. Thereafter we applied Fourier low-pass filters of 5, 15, 30, 60 and 180 days on T-air, TP, PET and tracked their effects through the soil climate model's state variables and outputs. This was done using a sandy and a heavy clay soil and an 89-year daily time-series from a meteorological station in Quebec (Canada). The Fourier spectra showed that the variance for T-air, PET and r(e_temp) was dominated by an annual cycle, as could be expected. There was no yearly cycle for TP. The variation in r(e_temp) explained most of the variance in r(e_crop). The soil climate module outputs were not sensitive to low-pass filtering of PET. A daily time-step was needed to avoid overestimating r(e_crop) for the sandy soil. Using a weekly time-step for TP and T-air allowed us to explain about 80% of the variance in r(e_crop) for the heavy clay soil. This study also indicates that the standard leaf (and green) area index functions for calculating transpiration should receive more attention, since they have significant effects on the state and output variables. (C) 2011 Elsevier B.V. All rights reserved.
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| 5. |
- Bolinder, Martin, et al.
(författare)
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Estimating carbon inputs to soil in forage-based crop rotations and modeling the effects on soil carbon dynamics in a Swedish long-term field experiment
- 2012
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Ingår i: Canadian Journal of Soil Science. - 0008-4271. ; 92, s. 821-833
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Tidskriftsartikel (refereegranskat)abstract
- Bolinder, M. A., Katerer, T., Andren, O. and Parent, L. E. 2012. Estimating carbon inputs to soil in forage-based crop rotations and modeling the effects on soil carbon dynamics in a Swedish long-term field experiment. Can. J. Soil Sci. 92: 821-833. There is a need to improve the understanding of soil organic C (SOC) dynamics for forage-based rotations. A key requisite is accurate estimates of the below-ground (BG) C inputs to soil. We used the Introductory Carbon Balance Model (ICBM) to investigate the effects of C input assumptions on C balances with data from a 52-yr field experiment in northern Sweden. The main objective was to validate an approach for estimating annual crop residue C inputs to soil using the data from a continuous forage-based rotation (A). A rotation with only annual crops and more frequent tillage events (D) was used to obtain a rough estimate of the effect of tillage on SOC dynamics. The methodology used to estimate annual crop residue C inputs to soil gave a good fit to data from four out of the six large plots for rotation A. The approximate effects of more frequent tillage in rotation D increased SOC decomposition rate by about 20%. These results allow us to have more confidence in predicting SOC balances for forage-based crop rotations. Root biomass measurements used for calculating BG C inputs were also reviewed, and we show that they have not changed significantly during the past 150 yr.
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| 6. |
- Bolinder, Martin, et al.
(författare)
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Long-term soil organic carbon and nitrogen dynamics in forage-based crop rotations in Northern Sweden (63-64 degrees N)
- 2010
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Ingår i: Agriculture, Ecosystems and Environment. - : Elsevier BV. - 0167-8809 .- 1873-2305. ; 138, s. 335-342
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Tidskriftsartikel (refereegranskat)abstract
- For carbon sequestration estimates it is necessary to evaluate effects of management practices on soil organic carbon (SOC) and nitrogen (SON) dynamics in a wide range of production systems and climatic zones. At higher latitudes with cold temperate climate, crop rotations dominated by forage are common and often highly productive-and the climate as well as the forage cropping systems favour large stocks of SOC and SON. The objective of this study was to estimate SOC and SON stock dynamics in the arable layer (0-25 cm) for different 6-year forage-based rotations using sampling data from three long-term field experiments in Northern Sweden. At the site with the lowest initial amount of SOC (8.2 kg C m(-2)), SOC stocks increased by 12 g C m(-2) yr(-1) over a 50-year period for the continuous forage rotation ('A'), which received ca. 10 Mg ha(-1) of cattle manure per year (wet mass). At the same site, SOC stocks were more or less at steady state in rotation 'B' with 4 years of forage and 2 years of annuals, receiving the same amount of manure. For rotation 'C' with 3 years of forage and receiving ca. 6.5 Mg ha(-1) of manure, the SOC stocks decreased by 18 g C m(-2) yr(-1,) while the SOC stocks for rotation 'D' with only annuals and no manure application decreased by 24 g C m(-2) yr(-1). At the other two sites, with higher initial SOC stocks (12.1 and 12.8 kg C m(-2)), the SOC stocks in all treatments decreased during a 30-year period, at a rate ranging from 11 to 95 g C m(-2) yr(-1). Similar trends were found for the change in SON stocks, although they were more variable. The topsoil SOC stocks were high compared to southern Sweden and regions of similar climate in northeast Canada, in particular for rotation A. These results indicate that the estimates of SOC and SON storage rate changes for a particular management system van vary widely within a small region of a given climatic zone. (C) 2010 Elsevier B.V. All rights reserved.
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| 7. |
- Bolinder, Martin, et al.
(författare)
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Spatial and temporal variability of soil biological activity in the Province of Quebec, Canada (45-58 degrees N, 1960-2009) - calculations based on climate records
- 2013
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Ingår i: Climatic Change. - : Springer Science and Business Media LLC. - 0165-0009 .- 1573-1480. ; 117, s. 739-755
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Tidskriftsartikel (refereegranskat)abstract
- Climate records of air temperature (AT) and total precipitation (TP) are standard inputs for soil carbon dynamic models, i.e., for calculating temperature and moisture effects on soil biological activity. In this study our objective was to determine both spatial and temporal differences in soil biological activity in the Province of Qu,bec, Canada. Soil biological activity was here calculated on a daily basis with the ICBM re_clim parameter using data from weather stations. When keeping soil and crop properties constant, re_clim (unitless) allows us to assess relative differences in soil biological activity. The magnitude of the temporal changes in re_clim, AT and TP were analyzed using Sen's slope, which is a nonparametric method used to determine the presence of a trend component. The re_clim varied across Qu,bec from 0.50 (58 A degrees N) to a high of 1.66 (45 A degrees N). Considering only the area with significant agricultural production, re_clim varied from 0.99 at Gasp, (48 A degrees N) to 1.66 at Philipsburg (45 A degrees N), i.e., soil organic carbon (SOC) decomposition rate is 68 % higher at the latter site (1.66/0.99) and correspondingly more C input is needed to maintain SOC. Soil biological activity increased from 1960 to 2009, with a mean slope variation in re_clim of about +10 %. The temporal variation in AT had more influence than that of TP. For 1980-2009 the mean annual slope of re_clim was significantly different from zero for 29 out of 49 climate records (mean = +14 %; N = 29). We also emphasize that analysis of seasonal changes in AT is an issue that needs further attention, as well as modeling climate-induced changes in SOC dynamics based on future climate scenarios.
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| 8. |
- Börjesson, Gunnar, et al.
(författare)
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Four Swedish long-term field experiments with sewage sludge reveal a limited effect on soil microbes and on metal uptake by crops
- 2014
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Ingår i: Journal of Soils and Sediments. - : Springer Science and Business Media LLC. - 1439-0108 .- 1614-7480. ; 14, s. 164–177-
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Tidskriftsartikel (refereegranskat)abstract
- Purpose This study aims to study the effect of sewage sludge amendment on crop yield and on microbial biomass and community structure in Swedish agricultural soils. Materials and methods Topsoil samples (0-0.20 m depth) from four sites where sewage sludge had been repeatedly applied during 14-53 years were analysed for total C, total N, pH and phospholipid fatty acids (PLFAs). Heavy metals were analysed in both soil and plant samples, and crop yields were recorded. Results and discussion At all four sites, sewage sludge application increased crop yield and soil organic carbon. Sludge addition also resulted in elevated concentrations of some heavy metals (mainly Cu and Zn) in soils, but high concentrations of metals (Ni and Zn) in plant materials were almost exclusively found in the oldest experiment, started in 1956. PLFA analysis showed that themicrobial community structure was strongly affected by changes in soil pH. At those sites where sewage sludge had caused low pH, Gram-positive bacteria were more abundant. However, differences in community structure were larger between sites than between the treatments. Conclusions At all four sites, long-term sewage sludge application increased the soil organic carbon and nitrogen content, microbial biomass and crop yield. Long-term sewage sludge application led to a decrease in soil pH. Concentrations of some metals had increased significantly with sewage sludge application at all sites, but the amounts of metals added to soil with sewage sludge were found not to be toxic for microbes at any site.
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| 9. |
- Börjesson, Gunnar, et al.
(författare)
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Markbiologisk uppföljning i åkermark : en undersökning av fosfolipidfettsyror (PLFA) som möjlig mikrobiologisk indikator
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Monitoring and assessment of agricultural soils has become requested as means to detect changes in soil quality. Among possible microbial indicators for monitoring soil quality, the most common methods include microbial biomass, respiration, N mineralization and a community profiling method. Among the latter, the most used seem to be DGGE (denaturing gradient gel electrophoresis), PLFA (phospholipid fatty acids), and CLPP (community level physiology profile) analyses. Here we report results from an investigation of the PLFA analysis for the possible use as an indicator for monitoring soil quality. Soil samples were taken 2009 in the Ultuna soil organic matter field experi-ment, which was started in 1956 for investigating the long-term effect of mineral N fertilizers and different organic amendments on crop yields, soil organic matter changes and soil physical properties. PLFAs were extracted from top- and subsoils in ten treatments. PLFA concentrations were compared to other variables, such as total carbon, total nitrogen, pH and respiration, but also to other results reported earlier from the same experiment. Total PLFAs in topsoil samples (0-20 cm) were highest in the sewage sludge (O) treatment, which was almost reflected in subsoil samples, although the highest mean value among those samples was found for the farmyard manure (J) treatment. A good correlation was observed between total PLFAs in topsoil samples and total carbon, but total PLFAs were even better correlated with total nitrogen (r=0.81; p<0.0001). Subsoil samples (27-40 cm depth) reflected topsoil samples for total PLFAs, but the individual PLFAs revealed that the composition of the microbial communities were entirely different. The presence of cyclic fatty acids in the sewage sludge treatment indicated some kind of stress for gram-negative bacteria, probably caused by heavy metals, although a negative effect of the sewage sludge application could not be seen in other ways, e.g. crop yield. In conclusion, the PLFA analysis can give valuable information about the microbial community in soil samples. It can be used in a monitoring programme, although the recommendation is that it would be preferable to combine the PLFA analysis with other methods, for example CLPP, in order to determine trends and changes of microbial communities and activities in soils
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| 10. |
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