| 1. |
- Bolinder, Martin
(författare)
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Contribution of Regis R. Simard to phosphorus research in agroecosystems and future prospects
- 2009
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Ingår i: Canadian Journal of Soil Science. - 0008-4271. ; 89, s. 145-155
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Tidskriftsartikel (refereegranskat)abstract
- Can. J. Soil Sci. 89: 145-155. In this paper we present the soil test P saturation, budget, and fractionation procedures used in R. R. Simard's laboratory. We expand that work to: (1) Mehlich-III P saturation index using a weighting factor for Fe accumulation in soils; (2) P budget including below-ground biomass; and (3) compositional data analysis of P fractions to describe changing patterns of soil P fractions that differ in their availability to plants and risk to the environment. The Mehlich III P and Al two-way classification applied to forage crops by Simard and co-workers was replaced by the P/Al ratio test for P fertilizer recommendation in Quebec. The concept was further expanded to (P/[Al+gamma Fe), where gamma is 0 or 1 in mineral soils and 5 in organic soils. To provide a more complete picture of the P budget and risk index in agroecosystems, it Would be advantageous to consider root P, despite limited data. Using compositional analysis for a closed information space or simplex, a perturbation vector describing relative increase or decrease in P pools in response to a driving variable as well as the simplicial distance between control and modified soil P simplexes showed that added P primarily influenced the most labile inorganic P fractions (resin-P(i) and NaHCO(3)-P(i)) in five Quebec gleysolic soils. Changes in P patterns were more prominent in coarse- than in fine-textured soils. Soil P saturation, the P budget and proximate P analysis used by R.R. Simard support current progress on P issues. Future research should address gamma as a function of soil Fe forms (hydroxide or bound to organic matter), below-ground P in the P budget, and soil P compositional patterns in response to driving variables.
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| 2. |
- 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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| 3. |
- Bolinder, Martin, et al.
(författare)
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Net primary productivity and below-ground crop residue inputs for root crops: Potato (Solanum tuberosum L.) and sugar beet (Beta vulgaris L.)
- 2015
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Ingår i: Canadian Journal of Soil Science. - 0008-4271. ; 95, s. 87-93
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Tidskriftsartikel (refereegranskat)abstract
- Root crops are significant in agro-ecosystems of temperate climates. However, the amounts of crop residues for these crop types are not well documented and they need to be accounted for in the modeling of soil organic carbon dynamics. Our objective was to review field measurements of root biomass left in the soil as crop residues at harvest for potato and sugar beet. We considered estimates for crop residue inputs as root biomass presented in the literature and some unpublished results. Our analysis showed that compared to, for example, cereals, the contribution of below-ground net primary productivity (NPP) to crop residues is at least two to three times lower for root crops. Indeed, the field measurements indicated that root biomass for topsoils only represents on average 25 to 30 g dry matter (DM) m(-2) yr(-1). Other estimates, albeit variable and region-specific, tended to be higher. We suggest relative plant DM allocation coefficients for agronomic yield (R-P), above-ground biomass (R-S) and root biomass (R-R) components, expressed as a proportion of total NPP. These coefficients, representative for temperate climates (0.739:0.236:0.025 for potato and 0.626:0.357:0.017 for sugar beet), should be useful in the modeling of agro-ecosystems that include root crops.
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| 4. |
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| 5. |
- Clegg, S, et al.
(författare)
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Rhizospheric P and K in forest soil manipulated with ammonium sulfate and water
- 1997
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Ingår i: CANADIAN JOURNAL OF SOIL SCIENCE. - : AGR INST CANADA. - 0008-4271. ; 77:4, s. 525-533
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This study shows how the stress manipulations, ammonium sulfate, drought and irrigation changed the P and K status of three soil fractions (bulk soil, rhizosphere and soil-root interface) from E, Bh and Bs horizons of a Norway spruce stand in southwestern
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| 6. |
- Gobran, GR, et al.
(författare)
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A conceptual model for nutrient availability in the mineral soil-root system
- 1996
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Ingår i: CANADIAN JOURNAL OF SOIL SCIENCE. - : AGR INST CANADA. - 0008-4271. ; 76:2, s. 125-131
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We propose a conceptual model based on our results from rhizospheric studies of a Norway spruce stand growing on a nutrient poor podzol in Southwest Sweden. We assume that dynamic linkages exist between three soil fractions: bulk soil, rhizosphere (Rhizo)
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| 7. |
- Haei, Mahsa, et al.
(författare)
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Snow removal reduces annual cellulose decomposition in a riparian boreal forest
- 2013
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Ingår i: Canadian Journal of Soil Science. - 0008-4271. ; 93, s. 427-433
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Tidskriftsartikel (refereegranskat)abstract
- Decomposition is a key process in carbon and nutrient cycling. However, little is known about its response to altered winter soil temperature regimes in boreal forests. Here, the impact of soil frost on cellulose decomposition over 1 yr and soil biotic activity (bait-lamina sticks) over winter, in spring, and in summer was investigated using a long-term (9-yr) snow-cover manipulation experiment in a boreal Picea abies forest. The experiment consisted of the treatments: snow removal, increased insulation, and ambient control. The snow removal treatment caused longer and deeper soil frost (minimum temperature - 8.6 degrees C versus - 1.4 degrees C) at 10 cm soil depth in comparison with control, while the increased insulation treatment resulted in nearly no soil frost during winter. Annual cellulose decomposition rates were reduced by 46% in the snow removal manipulation in comparison with control conditions. Increased insulation had no significant effect on decomposition. The decomposition was mainly driven by microorganisms, as no significant difference was observed for containers enclosed with a 44-mu m and a 1-mm mesh. Soil biotic activity was slightly increased by both the snow removal and the increased insulation treatment in comparison with control conditions over winter. However, this effect disappeared over spring and summer. We conclude that soil frost can have strong effects on decomposition in boreal ecosystems. Further studies should investigate to which degree the observed reduction in decomposition due to reduced snow cover in winter slows or even offsets the expected increase in decomposition rates with global warming.
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