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| 2. |
- Andresen, Louise C., 1974, et al.
(författare)
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Moderate nitrogen retention in temperate heath ecosystem after elevated CO2, drought and warming through 7years
- 2023
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Ingår i: European Journal of Soil Science. - 1351-0754 .- 1365-2389. ; 74:4
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen (N) dynamic is one of the main controlling factors of responses to climate change in N-limited terrestrial ecosystems, which rely on nutrient re-cycling and retention. In this study we investigate the N partitioning in ecosystem compartments of a grassland heath, and the impact of multiple climate change factors on long-term N retention after 15N pulse labelling. The impacts of elevated carbon dioxide (eCO2), warming and drought and the treatments in combination on ecosystem N retention was investigated in a field scale manipulation experiment. A six-year time-course was assessed by pulse-labelling with the stable N isotope 15N and by sampling after 1 day, 1 year and 6years. After the six years we observed that the total ecosystem retained 42 % of the amended 15N across treatments (recovery of the amended 15N in the pool). The fate of the applied 15N was mainly stabilisation in soil, with 36 % recovery, while the plant compartment and microbial biomass each retained only 1-2 % of the added 15N. This suggests a moderate retention of N, for all treatments, as compared to similar long-term studies of forest ecosystems. A decreased ammonium and vegetation N pool combined with higher 15N retention in the soil at eCO2 treatments suggests that eCO2 promoted processes that immobilize N in soil, while warming counteracted this when combined with eCO2. Drought treatments contrastingly increased the vegetation N pool. We conclude that as the organic soil layer has the main capacity for N storage in a temperate heathland-grassland, it is important for buffering nutrient availability and maintaining a resilient ecosystem. However, the full treatment combination of drought, warming and eCO2 did not differ in 15N recovery from the controls, suggesting unchanged long-term consequences of climate change on retention of pulse added N in this ecosystem.
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| 3. |
- Baken, S., et al.
(författare)
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Ageing of vanadium in soils and consequences for bioavailability
- 2012
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Ingår i: European Journal of Soil Science. - : Elsevier. - 1351-0754 .- 1365-2389. ; 63:6, s. 839-847
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Tidskriftsartikel (refereegranskat)abstract
- Total vanadium (V) concentrations in soils commonly range from 20 to 120 mg kg-1. Vanadium added directly to soils is more soluble than geogenic V and can be phytotoxic at doses within this range of background concentrations. However, it is unknown how slow sorption reactions change the fate and effect of added V in soils. This study addresses the changes in V solubility, toxicity and bioavailability in soils over time. Four soils were amended with pentavalent V in the form of a soluble vanadate salt, and extractable V concentrations were monitored over 100 days. The toxicity to barley and tomato plants was evaluated in freshly spiked soils and in the corresponding aged soils that were equilibrated for up to 330 days after spiking. The V concentrations in 0.01 m CaCl2 soil extracts decreased approximately two-fold between 14 and 100 days after soil spiking, and the reaction kinetics were similar for all soils. The phytotoxicity of added V decreased on average two-fold between freshly spiked and aged soils. The reduced toxicity was associated with a corresponding decrease in V concentrations in the isolated soil solutions and in the shoots. The V speciation in the soil solution of the aged soils was dominated by V(V); less than 8% was present as V(IV). Oxalate extractions suggest that the V(V) added to soils is predominantly sorbed onto poorly crystalline oxyhydroxides. It is concluded that the toxicity of V measured in freshly spiked soils may not be representative of soils subject to a long-term V contamination in the field.
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| 4. |
- Barao, L., et al.
(författare)
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Pedogenic and biogenic alkaline-extracted silicon distributions along a temperate land-use gradient
- 2014
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Ingår i: European Journal of Soil Science. - : Wiley. - 1365-2389 .- 1351-0754. ; 65:5, s. 693-705
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Tidskriftsartikel (refereegranskat)abstract
- The primary source of dissolved silicon (Si: DSi) is the weathering of silicate minerals. In recent years, it has been shown that Si cycling through vegetation creates a more soluble Si pool in the soil, as amorphous Si (ASi) deposits in plants (phytoliths) are returned to the soil through litter. Amorphous Si accumulation in soils depends on a number of factors, including land use. In addition to the biogenic ASi fraction, soils contain other non-biogenic amorphous and sorbed Si fractions that could contribute significantly to DSi export to rivers, but hitherto these Si fractions have been difficult to separate from each other with traditionally applied extraction methods. The objective of this paper is to understand better how land use affects the distribution of the different extractable Si fractions. We re-analysed samples from the land-use gradient studied previously by Clymans et al. () with a continuous Si and aluminium (Al) extraction technique. Different extractable Si fractions of biogenic or pedogenic origin were successfully separated on the basis of their dissolution in alkaline solutions (Na2CO3 and NaOH) and Si:Al ratios. We show that forests store almost all alkaline extractable Si (AlkExSi) in the pedogenic fraction while the importance of phytoliths increases with human disturbance to become the dominant fraction in the AlkExSi pool at the arable site. The pedogenic AlkExSi pool is also more reactive than the phytolith-bound Si. Conversely, pastures and croplands tend to preserve phytoliths in the soil, which are less reactive, decreasing the potential of DSi export relative to forested ecosystems.
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| 5. |
- Boye, Kristin, et al.
(författare)
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Quantification of chemical sulphur species in bulk soil and organic sulphur fractions by S K-edge XANES spectroscopy
- 2011
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 62, s. 874–881-
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Tidskriftsartikel (refereegranskat)abstract
- A new data treatment method for fitting spectra obtained by sulphur (S) K-edge X-ray absorption near-edge structure (XANES) spectroscopy was used to quantify the chemical S speciation at three experimental sites with arable soils receiving the same long-term field treatments. Two treatments, crop residue (CR) incorporation and farmyard manure (FYM) application, with equal applications of mineral nutrients were included in the study. In the new data treatment method, internally calibrated spectra of dilute solutions (30 mm) of model compounds were used to fit the sample spectra. This greatly enhanced the reliability of quantitative determination of contributing S species in soil samples and soil extracts. The results indicated that long-term FYM application shifted S species composition from highly oxidized towards intermediate oxidization in two of the soils, but in the third soil the opposite trend was observed. Sulphur XANES spectroscopy of acetylacetone extracts of physically protected and unprotected organic S in two of the soils revealed that physical protection was not related to S speciation; however, intermediate forms of oxidized S species appeared to accumulate in the residual S pool (not extractable by acetylacetone)
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| 6. |
- Braun, Sabina, et al.
(författare)
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Modelling heterogeneous phosphate sorption kinetics on iron oxyhydroxides and soil with a continuous distribution approach
- 2018
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 69, s. 475-487
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Tidskriftsartikel (refereegranskat)abstract
- The kinetics of orthophosphate (PO4) sorption in soil has far reaching consequences on its long-term fate. Traditionally, a distinction is made between fast, reversible adsorption and slow fixation. The kinetics are commonly described by compartmental models (CMs) assuming kinetically distinct homogeneous pools (e.g. a rapid- and slow-sorbing pool), with phenomenological equations or with complex diffusion-based models. Alternatively, this process can be described by assuming frequency distributions of both adsorption and desorption rate constants and, thereby, enabling better description of experimental data with fewer adjustable parameters. Here, we developed such a rate constant distribution (RCD) model and compared it with CMs and other commonly used rate equations. Batch (PO4)-P-33 sorption was measured in agitated suspensions between 2minutes and 20days after spiking in 13 contrasting types of soil and two iron oxyhydroxides. Overall, the RCD model, with three adjustable parameters, describes the data better than the other models tested. The so-called slow reactions, denoted as the factor change in soluble (PO4)-P-33 between 1 and 20days after spiking, were described better by the RCD model and ranged from 1.0 (i.e. no change) to 6.9. The extent of slow reactions increased with the increase in the fraction of poorly crystalline iron in the soil (r=0.69; P=0.0088). Equilibrium was elusive up to 20days for PO4 sorption on ferrihydrite and on soil samples with a large fraction of poorly crystalline iron oxyhydroxides. The RCD model code is available as freeware from the first author.
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| 7. |
- Börjesson, Gunnar
(författare)
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A comparison of soil tests for available phosphorus in long-term field experiments in Europe
- 2017
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 68, s. 873-885
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Tidskriftsartikel (refereegranskat)abstract
- Most soil tests for available phosphorus (P) perform rather poorly in predicting crop response. This study was set up to compare different established soil tests in their capacity to predict crop response across contrasting types of soil. Soil samples from long-term field experiments, the oldest >100 years old, were collected in five European countries. The total number of soil samples (n = 218), which differed in cropping and P treatment, and originated from 11 different soil types, were analysed with five tests: ammonium oxalate (Ox), ammonium lactate (AL), Olsen P, 0.01 m CaCl2 and the diffusive gradient in thin film (DGT). The first three tests denote available P quantity (Q), whereas the last two indicate P intensity (I) of the soil solution. All five tests were positively related to the crop yield data (n = 317). The Q-tests generally outperformed I-tests when evaluated with goodness of fit in Mitscherlich models, but critical P values of the I-tests varied the least among different types of soil. No test was clearly superior to the others, except for the oxalate extraction, which was generally poor. The combination of Q- and I-tests performed slightly better for predicting crop yield than any single soil P test. This Q + I analysis explains why recent successes with I-tests (e.g. DGT) were found for soils with larger P sorption than for those in the present study. This systematic evaluation of soil tests using a unique compilation of established field trials provides critical soil P values that are valid across Europe.Highlights We compared soil P tests for predicting crop response across contrasting soil types. No test was clearly superior to the others except for the oxalate extraction, which was generally poor. This study suggests that intensity tests do not perform markedly better than quantity tests. The evaluation of soil P tests on this unique dataset provided critical soil P values across Europe.
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| 8. |
- Börjesson, Gunnar, et al.
(författare)
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Seasonal dynamics of the soil microbial community: assimilation of old and young carbon sources in a long-term field experiment as revealed by natural C-13 abundance
- 2016
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 67, s. 79-89
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Tidskriftsartikel (refereegranskat)abstract
- Microbial biomass is a small part of the total soil organic carbon (SOC) pool, but plays a major role in its turnover. A field experiment in Sweden, amended with different mineral and organic materials since 1956, was changed from continuous C3 plants to C4 vegetation (silage maize) in 2000. In 2012, soil samples from three fertilizer treatments (calcium nitrate, calcium nitrate plus straw and sewage sludge) and two controls (bare fallow and cropped unfertilized) were taken on three occasions (before, during and after cropping). Phospholipid fatty acids (PLFAs) were extracted from all soil samples and analysed for C-12 and C-13 contents in individual PLFAs. Seasonal variation in total PLFAs was small except for the most SOC-rich treatment (sewage sludge). Weighted means of C-13 in PLFAs showed that the plots fertilized with calcium nitrate only had the largest C-13 values in PLFAs before (-20.24 parts per thousand) and after the vegetation period (-20.37 parts per thousand). However, during the vegetation period the values were much smaller (-21.85 parts per thousand). This coincided with a strong increase in the PLFA 18:26,9, indicating the use of old organic matter by fungi. Monounsaturated PLFAs indicative of Gram-negative bacteria were more frequent before and after the growing season. This observed rebound' effect of the C-13 PLFA values during the vegetation period indicates that seasonal turnover of the microbial biomass can be substantial.
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| 9. |
- Börjesson, Gunnar
(författare)
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Strong pH influence on N2O and CH4 fluxes from forested organic soils
- 2009
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 60, s. 311-320
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Tidskriftsartikel (refereegranskat)abstract
- Greenhouse gas (GHG) emissions from farmed organic soils can have a major impact on national emission budgets. This investigation was conducted to evaluate whether afforestation of such soils could mitigate this problem. Over the period 1994-1997, emissions of methane (CH4) and nitrous oxide (N2O) were recorded from an organic soil site in Sweden, forested with silver birch (Betula pendula Roth), using static field chambers. The site was used for grazing prior to forestation. Soil pH and soil carbon content varied greatly across the site. The soil pH ranged from 3.6 to 5.9 and soil carbon from 34 to 42%.The mean annual N2O emission was 19.4 (+/- 6.7) kg N2O-N ha(-1) and was strongly correlated with soil pH (r = -0.93, P < 0.01) and soil carbon content (r = 0.97, P < 0.001). The N2O emissions showed large spatial and temporal variability with greatest emissions during the summer periods. The site was a sink for CH4 (i.e. -0.8 (+/- 0.5) kg CH4 ha(-1) year(-1)) and the flux correlated well with the C/N ratio (r = 0.93, P < 0.01), N2O emission (r = 0.92, P < 0.01), soil pH (r = -0.95, P < 0.01) and soil carbon (r = 0.97, P < 0.001). CH4 flux followed a seasonal pattern, with uptake dominating during the summer, and emission during winter.This study indicates that, because of the large N2O emissions, afforestation may not mitigate the GHG emissions from fertile peat soils with acidic pH, although it can reduce the net GHG because of greater CO2 assimilation by the trees compared with agricultural crops.
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| 10. |
- Campbell, Colin
(författare)
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Comparison of soil carbon stocks in Scottish soils between 1978 and 2009
- 2013
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 64, s. 455-465
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Tidskriftsartikel (refereegranskat)abstract
- The change in soil carbon (C) stock over a 19-31-year period (mean 25years) has been measured at 179 sites on a 20-km grid across Scotland. Sampling was by horizon from a profile pit. Although soil bulk density determinations were absent at the first sampling time, we used bulk density values from the second sampling time calibrated against NIR spectra to predict the missing values. There was no detectable change in overall total soil C stock (mean +/- standard error, to a depth of 100cm), which was 266 +/- 15 and 270 +/- 15tCha(-1) for the first and second sampling times, respectively, or generally in C stock within specific vegetation or soil types. The exception was for soils under woodland, excluding those on deep peat, which exhibited a significant (P=0.05) gain of 1.0tCha(-1)year(-1). Soils under woodland (mainly coniferous plantation) also showed a significant (P=0.04) increase in C content (gkg(-1)), a significant decrease in bulk density (P=0.006) and an increase in the thickness of the Litter-Fermentation-Humus (LFH) layer (P=0.06). Recalculating the C stock to a depth of 15cm showed a significant increase in overall C stock (when deep peat sites were excluded) as well as specifically in moorland and woodland soils, suggesting that had we sampled only to 15cm, we would have reached a different conclusion. Both improved grassland soils and those initially under arable cultivation showed a significant decrease in C content. However, the mean thickness of Ap horizons increased from 29 to 32cm, with a concomitant decrease in C content and a slight increase in bulk density; this we ascribe to deeper ploughing between the sample periods. In the context of possible soil C losses, we can be 95% confident that the mean loss does not exceed 0.2%year(-1) and 99% confident that it does not exceed 0.4%year(-1).
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