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| 2. |
- Ulen, Barbro, et al.
(författare)
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Recession of phosphorus and nitrogen concentrations in tile drainage water after high poultry manure applications in two consecutive years
- 2014
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Ingår i: Agricultural Water Management. - : Elsevier BV. - 0378-3774. ; 146, s. 208-217
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Tidskriftsartikel (refereegranskat)abstract
- High application rates of poultry (Gallus gallus domesticus) manure can impair drainage water quality through enhanced leaching of phosphorus (P) and nitrogen (N). In two years with application rates of broiler chicken manure corresponding to 99 and 79 kg P ha(-1) year to a tile-drained field with loamy soil in SW Sweden, mean concentrations of dissolved reactive P (DRP) were significantly higher (p < 0.05) elevated in peak water flows in the two winter periods than in 19 previous years without manure application of any kind. With the water sampling strategy used, this effect was observed 5 and 4 months after application, when 160 and 140 mm of water, respectively, had discharged. Flow recession of distinct peak flows was illustrated as exponential decay to time, with half-life 48 h, while recession of elevated DRP concentrations had approximately 2 h half-life. In the following 12 years, only moderate amounts of mineral P were applied (on three occasions) to this topsoil with 11% degree of P saturation measured in acid soil extract (DPS-AL). Mean DRP concentrations in peak, base and intermediate flow in that period were moderate, i.e. similar to those before manure application. In contrast, high concentrations of nitrate N (NO3-N) in peak, base and intermediate flows occurred in the 8-year period following manure application. Mean NO3-N concentration in peak flows decreased approximately linearly, by 5.6 mu g L-1, for every mm of total water discharge. Thus poultry manure should not be applied in repeated high loads in order to avoid the risk of enhanced P leaching losses during subsequent peak flows. Furthermore, N leaching losses during peak and base flow conditions can persist for longer than a 5-year crop rotation and were shown here to recede at a slower relative rate than P. (C) 2014 Elsevier B.V. All rights reserved.
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- Wennerholm, Ulla-Britt, 1948, et al.
(författare)
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Induction of labour at 41 weeks versus expectant management and induction of labour at 42 weeks (SWEdish Post-term Induction Study, SWEPIS) : multicentre, open label, randomised, superiority trial
- 2019
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Ingår i: The BMJ. - : BMJ Publishing Group Ltd. - 1756-1833 .- 0959-8138. ; 367
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate if induction of labour at 41 weeks improves perinatal and maternal outcomes in women with a low risk pregnancy compared with expectant management and induction of labour at 42 weeks.DESIGN: Multicentre, open label, randomised controlled superiority trial.SETTING: 14 hospitals in Sweden, 2016-18.PARTICIPANTS: 2760 women with a low risk uncomplicated singleton pregnancy randomised (1:1) by the Swedish Pregnancy Register. 1381 women were assigned to the induction group and 1379 were assigned to the expectant management group.INTERVENTIONS: Induction of labour at 41 weeks and expectant management and induction of labour at 42 weeks.MAIN OUTCOME MEASURES: The primary outcome was a composite perinatal outcome including one or more of stillbirth, neonatal mortality, Apgar score less than 7 at five minutes, pH less than 7.00 or metabolic acidosis (pH <7.05 and base deficit >12 mmol/L) in the umbilical artery, hypoxic ischaemic encephalopathy, intracranial haemorrhage, convulsions, meconium aspiration syndrome, mechanical ventilation within 72 hours, or obstetric brachial plexus injury. Primary analysis was by intention to treat.RESULTS: The study was stopped early owing to a significantly higher rate of perinatal mortality in the expectant management group. The composite primary perinatal outcome did not differ between the groups: 2.4% (33/1381) in the induction group and 2.2% (31/1379) in the expectant management group (relative risk 1.06, 95% confidence interval 0.65 to 1.73; P=0.90). No perinatal deaths occurred in the induction group but six (five stillbirths and one early neonatal death) occurred in the expectant management group (P=0.03). The proportion of caesarean delivery, instrumental vaginal delivery, or any major maternal morbidity did not differ between the groups.CONCLUSIONS: This study comparing induction of labour at 41 weeks with expectant management and induction at 42 weeks does not show any significant difference in the primary composite adverse perinatal outcome. However, a reduction of the secondary outcome perinatal mortality is observed without increasing adverse maternal outcomes. Although these results should be interpreted cautiously, induction of labour ought to be offered to women no later than at 41 weeks and could be one (of few) interventions that reduces the rate of stillbirths.TRIAL REGISTRATION: Current Controlled Trials ISRCTN26113652.
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- Wesström, Ingrid, et al.
(författare)
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Effects of tile drainage repair on nutrient leaching from a field under ordinary cultivation in Sweden
- 2015
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Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 65, s. 228-238
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Tidskriftsartikel (refereegranskat)abstract
- Leaching losses of nitrogen (N), phosphorus (P) and potassium (K) from arable land can be high, with N and P contributing significantly to the eutrophication of lakes and coastal waters. This study examined whether agriculture management and drain repair changed the chemical properties of shallow groundwater and affected nutrient leaching in the field. The hydrology of a subsurface-drained agricultural observation field included in the Swedish water quality monitoring programme was simulated for the period 1976-2006 using the process-based, field-scale model DRAINMOD. On the assumption that the drainage system operated similarly before and after repair, 54% more water was assigned to low-moderate flow events. Measured concentrations of sulphate-sulphur (SO4-S), sodium (Na), chloride (Cl) and potassium (K) were significantly lower in shallow groundwater in the period before drainage system repair (1980-1998) than afterwards (1998-2010). The concentrations were also significantly correlated with the corresponding concentrations in near-simultaneously sampled drain water. A similar connection was not observed for Na and Cl in the period before drain repair. Elevated concentrations of nitrate-nitrogen (NO3-N) were recorded both in shallow groundwater and in drainage water from 1998 to 2010, especially after incorporation of chicken manure into the soil in 1998. Based on simulated discharge (assuming a functioning measuring station throughout), estimated flow-weighted mean NO3-N concentration in drainage water increased from 5.6 mg L-1 (1977-1998) to 15.7 mg L-1 in the period 1998-2000. Simultaneously, mean NO3-N concentration in shallow groundwater increased from 0.2 to 4.0 mg L-1, and then to 4.8 mg L-1 in the period 2000-2012. It was estimated that after drain repair, a greater proportion of infiltrated NO3-N entered the receiving stream directly via the outlet of the tile drainage system close to the field's monitoring station than was the case before repair.
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