| 1. |
- Bergström, Lars, et al.
(författare)
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Turnover and Losses of Phosphorus in Swedish Agricultural Soils: Long-Term Changes, Leaching Trends, and Mitigation Measures
- 2015
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Ingår i: Journal of Environmental Quality. - : Wiley. - 0047-2425 .- 1537-2537. ; 44, s. 512-523
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Tidskriftsartikel (refereegranskat)abstract
- Transport of phosphorus (P) from agricultural fields to water bodies deteriorates water quality and causes eutrophication. To reduce P losses and optimize P use efficiency by crops, better knowledge is needed of P turnover in soil and the efficiency of best management practices (BMPs). In this review, we examined these issues using results from 10 Swedish long-term soil fertility trials and various studies on subsurface losses of P. The fertility trials are more than 50 years old and consist of two cropping systems with farmyard manure and mineral fertilizer. One major finding was that replacement of P removed by crops with fertilizer P was not sufficient to maintain soil P concentrations, determined with acid ammonium lactate extraction. The BMPs for reducing P leaching losses reviewed here included catch crops, constructed wetlands, structure liming of clay soils, and various manure application strategies. None of the eight catch crops tested reduced P leaching significantly, whereas total P loads were reduced by 36% by wetland installation, by 39 to 55% by structure liming (tested at two sites), and by 50% by incorporation of pig slurry into a clay soil instead of surface application. Trend analysis of P monitoring data since the 1980s for a number of small Swedish catchments in which various BMPs have been implemented showed no clear pattern, and both upward and downward trends were observed. However, other factors, such as weather conditions and soil type, have profound effects on P losses, which can mask the effects of BMPs.
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| 2. |
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| 3. |
- Hong, Bongghi, et al.
(författare)
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Advances in NANI and NAPI accounting for the Baltic drainage basin : spatial and temporal trends and relationships to watershed TN and TP fluxes
- 2017
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 133:3, s. 245-261
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Tidskriftsartikel (refereegranskat)abstract
- In order to assess the progress toward eutrophication management goals, it is important to understand trends in land-based nutrient use. Here we present net anthropogenic nitrogen and phosphorus inputs (NANI and NAPI, respectively) for 2000 and 2010 for the Baltic Sea watershed. Overall, across the entire Baltic, between the 5-year periods centered on 2000 and 2010, NANI and NAPI decreased modestly by -6 and -4%, respectively, but with substantial regional variation, including major increases in the Gulf of Riga drainage basin (+19 and +58%, respectively) and decreases in the Danish Straits drainage basin (-25 and -40% respectively). The changes were due primarily to changes in mineral fertilizer use. Mineral fertilizers dominated inputs, at 57% of both NANI and NAPI in 2000, increasing to 68 and 70%, respectively, by 2010. Net food and feed imports declined over that period, corresponding to increased crop production; either fewer imports of food and feedstocks were required to feed humans and livestock, or more of these commodities were exported. A strong linear relationship exists between regional net nutrient inputs and riverine nutrient fluxes for both periods. About 17% of NANI and 4.7% of NAPI were exported to the sea in 2000; these relationships did not significantly differ from those for 2010. Changes in NANI from 2000 to 2010 across basins were directly proportional rather than linearly related to changes in total N (TN) fluxes to the sea (i.e., no change in NANI suggests no change in TN flux). Similarly, for all basins except those draining to the Baltic Proper, changes in NAPI were proportional to changes in total P (TP) fluxes. The Danish Straits decreased most between 2000 and 2010, where NANI and NAPI declined by 25 and 40%, respectively, and corresponding fluxes of TN and TP declined 31 and 18%, respectively. For the Baltic Proper, NAPI was relatively unchanged between 2000 and 2010, while riverine TP fluxes decreased 25%, due possibly to lagged effects of fertilizer reduction resulting from socio-political changes in the early 1990s or improvements in sewage treatment capabilities. For most regions, further reductions in NANI and NAPI could be achieved by more efficient production and greater substitution of manure for imported mineral fertilizers.
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| 4. |
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| 5. |
- McCrackin, Michelle L., et al.
(författare)
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A Century of Legacy Phosphorus Dynamics in a Large Drainage Basin
- 2018
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Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 32:7, s. 1107-1122
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Tidskriftsartikel (refereegranskat)abstract
- There is growing evidence that the release of phosphorus (P) from legacy stores can frustrate efforts to reduce P loading to surface water from sources such as agriculture and human sewage. Less is known, however, about the magnitude and residence times of these legacy pools. Here we constructed a budget of net anthropogenic P inputs to the Baltic Sea drainage basin and developed a three-parameter, two-box model to describe the movement of anthropogenic P though temporary (mobile) and long-term (stable) storage pools. Phosphorus entered the sea as direct coastal effluent discharge and via rapid transport and slow, legacy pathways. The model reproduced past waterborne P loads and suggested an similar to 30-year residence time in the mobile pool. Between 1900 and 2013, 17 and 27 Mt P has accumulated in the mobile and stable pools, respectively. Phosphorus inputs to the sea have halved since the 1980s due to improvements in coastal sewage treatment and reductions associated with the rapid transport pathway. After decades of accumulation, the system appears to have shifted to a depletion phase; absent further reductions in net anthropogenic P input, future waterborne loads could decrease. Presently, losses from the mobile pool contribute nearly half of P loads, suggesting that it will be difficult to achieve substantial near-term reductions. However, there is still potential to make progress toward eutrophication management goals by addressing rapid transport pathways, such as overland flow, as well as mobile stores, such as cropland with large soil-P reserves.
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| 6. |
- McCrackin, Michelle L., et al.
(författare)
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Opportunities to reduce nutrient inputs to the Baltic Sea by improving manure use efficiency in agriculture
- 2018
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Ingår i: Regional Environmental Change. - : Springer Science and Business Media LLC. - 1436-3798 .- 1436-378X. ; 18:6, s. 1843-1854
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Tidskriftsartikel (refereegranskat)abstract
- While progress has been made in reducing external nutrient inputs to the Baltic Sea, further actions are needed to meet the goals of the Baltic Sea Action Plan (BSAP), especially for the Baltic Proper, Gulf of Finland, and Gulf of Riga sub-basins. We used the net anthropogenic nitrogen and phosphorus inputs (NANI and NAPI, respectively) nutrient accounting approach to construct three scenarios of reduced NANI-NAPI. Reductions assumed that manure nutrients were redistributed from areas with intense animal production to areas that focus on crop production and would otherwise import synthetic and mineral fertilizers. We also used the Simple as Necessary Baltic Long Term Large Scale (SANBALTS) model to compare eutrophication conditions for the scenarios to current and BSAP-target conditions. The scenarios suggest that reducing NANI-NAPI by redistributing manure nutrients, together with improving agronomic practices, could meet 54–82% of the N reductions targets (28–43 kt N reduction) and 38–64% P reduction targets (4–6.6 kt P reduction), depending on scenario. SANBALTS output showed that even partial fulfillment of nutrient reduction targets could have ameliorating effects on eutrophication conditions. Meeting BSAP targets will require addressing additional sources, such as sewage. A common approach to apportioning sources to external nutrients loads could enable further assessment of the feasibility of eutrophication management targets.
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| 7. |
- Svanbäck, Annika, et al.
(författare)
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Influence of soil phosphorus and manure on phosphorus leaching in Swedish topsoils
- 2013
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Ingår i: Nutrient cycling in agroecosystems. - : Springer Science and Business Media LLC. - 1385-1314 .- 1573-0867. ; 96, s. 133-147
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden, subsurface transport of phosphorus (P) from agricultural soils represents the primary pathway of concern for surface water quality. However, there are mixed findings linking P in leachate with soil P and limited understanding of the interactive effects of applied P sources and soil test P on P leaching potential. Identifying soils that are susceptible to P leaching when manure is applied is critical to management strategies that reduce P loadings to water bodies. Intact soil columns (20 cm deep) from five long-term fertilization trials across Sweden were used in leaching experiments with simulated rainfall to explore the interactive effects of dairy cow (Bos taurus L.) manure application, soil test P and cropping system. Strong relationships were observed between ammonium-lactate extractable P in soil and dissolved reactive P (DRP) concentrations in leachate, although regression slopes varied across soils. For three soils, application of manure (equal to 21-30 kg P ha-1) to the soil columns significantly increased DRP leaching losses. The increase in DRP concentration was correlated to soil test P, but with wide variations between the three soils. For two soils leachate P concentrations after manure addition were independent of soil P status. Despite variable trends in P leaching across the different soils, P concentrations in leachate were always moderate from soils at fertilization rates equivalent to P removal with harvest. Results clearly stress the importance of long-term P balance to limit P leaching losses from Swedish agricultural soils.
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| 8. |
- Svanbäck, Annika, et al.
(författare)
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Long-term trends in phosphorus leaching and changes in soil phosphorus with phytomining
- 2015
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Ingår i: Journal of Soil and Water Conservation. - : Soil and Water Conservation Society. - 0022-4561 .- 1941-3300. ; 70:2, s. 121-132
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Tidskriftsartikel (refereegranskat)abstract
- Few mitigation strategies exist to reduce phosphorus (P) losses in leachate once soil P has built up. Phytomining, or harvesting a crop without application of fertilizer P to create a negative P balance, has been proposed as a strategy for lowering soil P levels and preventing P loss to runoff and leachate. In this study crops were grown and harvested over 7 to 16 years in undisturbed soil columns (105 cm [41 in] deep) with contrasting textures (loamy sand, sandy loam, silty clay loam, and clay) and high P levels, while P loss in leachate was measured. Soil test P in the topsoil (0 to 20 cm [0 to 8 in] depth) was significantly decreased from the beginning to the end of the study for all soils, while a significant decreasing trend in dissolved reactive P in leachate was only observed in one soil. Downward movement of P from the topsoil to deeper layers was indicated to occur in three out of four soils. Although phytomining lowered soil test P by 11% to 37% in topsoils over the 7 to 16 year period of the study, results indicate that soils with P content well above agronomic optimum may take a much longer time to reach the agronomic optimum.
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| 9. |
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| 10. |
- Svanbäck, Annika
(författare)
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Mitigation of phosphorus leaching from agricultural soils : improved fertilization and soil structure
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Phosphorus (P) is an essential element in crop production, but P losses from agricultural soils are a major contributor to surface water eutrophication. This thesis examined the effects of chemical soil properties and soil structure, as governed by agricultural management practices, on P leaching from agricultural soils and how this leaching can be reduced. An initial investigation on the effect of plant-available P concentration in the soil (P-AL) on topsoil P leaching from five soils clearly showed that topsoil P leaching depends not only on P status, but also on other soil characteristics. In three of these soils, increased P leaching after manure application was further amplified by high P-AL, while manure application did not affect topsoil P leaching in the other two soils. In a study assessing different management practices on a clay soil and the possible effect on P losses via tile drains, great spatial variation in P leaching was observed in the field, even though P-AL and discharge volume were relatively uniform across the field. Incorporation of quicklime (CaO) significantly reduced P leaching losses, primarily of particulate P, which was the dominant P form in drainage water. The other management options evaluated (conventional ploughing/shallow tillage; no P application/balanced P application; broadcasting/band spreading of fertilizer P) had no significant effects on P leaching. However, some effects of these management strategies could have been overshadowed by the large spatial variation in the data. Stopping P application and removing soil P with harvested crops (phytomining) showed potential to reduce excessive P levels in soils. After 7-9 years of no P application to the four soils studied, topsoil P-AL was lowered but most soils still had excessive levels. Only one soil, a clay soil with the lowest P-AL value in the study, showed a significant downward trend in leaching of dissolved reactive P. New knowledge outcomes were that: (i) the relationship between P-AL and topsoil P leaching clearly differs between soils, especially after manure application; (ii) incorporation of quicklime is a promising option for reducing P leaching from clay soils; and (iii) high P-AL values and P leaching may be reduced after phytomining, but this mitigation strategy takes a very long time.
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