| 1. |
- Ahmed, Mukhtar
(författare)
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Removing top leaves increases yield and nutrient uptake in maize plants
- 2020
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Ingår i: Nutrient cycling in agroecosystems. - : Springer Science and Business Media LLC. - 1385-1314 .- 1573-0867. ; 118, s. 57-73
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Tidskriftsartikel (refereegranskat)abstract
- Intraspecific competition for light affects nutrient uptake of maize, especially during the seed filling phase (from the blistering-stage to physiological-maturity). Partial leaf removal only affects the top leaves and improves the light-environment, which could then enhance nutrient uptake during the seed filling phase. However, there is a shortage of quantitative information on the yield effects of such a management measure. A 3-year field trial was conducted to evaluate the impact of different leaf removal treatments (no removal of leaves (D0: control), removal of two leaves (D2), removal of four leaves (D4), and removal of six leaves (D6) from maize-canopy) on total dry matter accumulation, and nitrogen, phosphorus, and potassium uptake at the blistering-stage and physiological-maturity, plus seed number per plant, seed weight, and seed yield at physiological maturity. Compared to D0, at physiological-maturity, D2 significantly increased total dry matter accumulation (by 9%), and uptake of nitrogen (by 5%), phosphorus (by 10%), and potassium (by 4%); while excessive leaf removal treatments considerably reduced dry matter accumulation and nutrient uptake. Importantly, during the seed filling phase of maize, treatment D2 significantly enhanced the uptake of nitrogen, phosphorus, and potassium by 76%, 40%, and 65%, respectively, compared to control. Treatment D2 increased seed number per plant (by 6.4%, from 448 under D0 to 477 in D2) and seed weight (by 5.7%). Relative to control, maize in D2 had 12%, 14%, and 11%, higher seed-yields in 2017, 2018, and 2019, respectively, and it also improved the economic profit when taking into account labor costs.
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| 2. |
- Aronsson, Helena, et al.
(författare)
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Combining mechanical control of couch grass (Elymus repens L.) with reduced tillage in early autumn and cover crops to decrease nitrogen and phosphorus leaching
- 2015
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Ingår i: Nutrient Cycling in Agroecosystems. - : Kluwer Academic Publishers. - 1385-1314 .- 1573-0867. ; 102:3, s. 383-396
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Tidskriftsartikel (refereegranskat)abstract
- Methods for control of couch grass (Elymus repens L.) with reduced tillage and cover crops to achieve low risk of nitrogen (N) and phosphorus (P) leaching were investigated. Treatments with reduced post-harvest tillage (one or two passes with duckfoot cultivator), hoeing between rows in combination with a cover crop, and a cover crop mown twice during autumn were compared with treatments with conventional disc cultivation and the control without tillage or cover crop. The study was conducted on a sandy soil in Sweden with measurements of N and P leaching. A 2-year experimental protocol was used, repeated twice. Treatments were implemented in the first year, and effects on couch grass (shoot density, shoot and rhizome biomass) were measured during autumn and in the second year. Significant effects of a single duckfoot cultivation and cover crop strategies were observed on couch grass shoot density in autumn but persistent effects were not verified. In conclusion, a single cultivation after harvest instead of repeated reduced the risk of N leaching and a cover crop in combination with hoeing or mowing effectively reduced it. Repeated cultivations resulted in mean annual N leaching of 26 kg N ha−1 compared with 20 kg in the treatment with one cultivation, 17 kg in the control, 16 and 12 kg in cover crop treatments with mowing and hoeing, respectively. The P leaching was small (0.04–0.09 P ha−1 year−1), but there were indications of increased P drainage water concentrations in the treatment with a cover crop which was mown. © 2015, The Author(s).
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| 3. |
- Aronsson, Helena, et al.
(författare)
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Effects of pig and dairy slurry application on N and P leaching from crop rotations with spring cereals and forage leys
- 2014
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Ingår i: Nutrient cycling in agroecosystems. - : Springer Science and Business Media LLC. - 1385-1314 .- 1573-0867. ; 98, s. 281-293
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Tidskriftsartikel (refereegranskat)abstract
- Two crop rotations dominated by spring cereals and grass/clover leys on a clay soil were studied over 2 years with respect to nitrogen (N) and phosphorus (P) leaching associated with pig or dairy slurry application in April, June and October. Leaching losses of total N (TN), total P (TP), nitrate-N and dissolved reactive P (DRP) were determined in separately tile-drained field plots (four replicates). Mean annual DRP leaching after October application of dairy slurry (17 kg P ha(-1)) to growing grass/clover was 0.37 kg ha(-1). It was significantly higher than after October application of pig slurry (13 kg ha(-1)) following spring cereals (0.16 kg ha(-1)) and than in the unfertilised control (0.07 kg P ha(-1)). The proportion of DRP in TP in drainage water from the grass/clover crop rotation (35 %) was higher than from the spring cereal rotation (25 %) and the control (14 %). The grass/clover rotation proved to be very robust with respect to N leaching, with mean TN leaching of 10.5 kg ha(-1) year(-1) compared with 19.2 kg ha(-1) year(-1) from the cereal crop rotation. Pig slurry application after cereals in October resulted in TN leaching of 25.7 kg ha(-1) compared with 7.0 kg ha(-1) year(-1) after application to grass/clover in October and 19.1 kg ha(-1) year(-1) after application to spring cereals in April. In conclusion, these results show that crop rotations dominated by forage leys need special attention with respect to DRP leaching and that slurry application should be avoided during wet conditions or combined with methods to increase adsorption of P to soil particles.
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| 4. |
- Börjesson, Gunnar, et al.
(författare)
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Soil fertility effects of repeated application of sewage sludge in two 30-year-old field experiments
- 2018
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Ingår i: Nutrient cycling in agroecosystems. - : Springer Science and Business Media LLC. - 1385-1314 .- 1573-0867. ; 112, s. 369-385
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Tidskriftsartikel (refereegranskat)abstract
- Recirculation of plant nutrients from waste materials back to agriculture is necessary in a sustainable food production system. In this study we investigated the long-term effect of direct land application of sewage sludge (SS) on soil fertility on two Swedish farms, where field experiments were set up in 1981 with three rates of SS (0, 4 and 12Mgdrymatterha(-1) every 4years) and three rates of mineral fertilisation, in a factorial design with four replicates. At one site, SS application tended to increase crop yield over time but, when plant nutrients were not limiting, the effect was only significant for spring barley. We deduced that improved soil structure was the main driver for this fertility enhancement after SS application, as indicated by lower soil bulk density and higher soil carbon concentration. After 30years, soil organic carbon stocks to 0.40m depth differed by up to 17Mgha(-1) between treatments. According to carbon balance calculations, retention of carbon derived from SS ranged between 18 and 20% for the soil layers analysed at the two sites. Soluble phosphorus (P) increased with sludge application rate, but represented only around 2% of the expected residual P according to P-balance calculations. The fertiliser value of nitrogen was also low, with only 3-8% nitrogen use efficiency. Heavy metals such as copper, zinc and mercury showed moderate accumulation in the soil, but elevated levels of metals were not detected in crops, even at the highest dose of SS. These results show that SS represents a valuable resource for improving soil fertility in terms of soil organic matter and soil structure, but its efficiency for nutrient cycling is very low within the time frame considered in the study.
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| 5. |
- Dahlin, Sigrun, et al.
(författare)
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Mulch N recycling in green manure leys under Scandinavian conditions
- 2011
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Ingår i: Nutrient cycling in agroecosystems. - : Springer Science and Business Media LLC. - 1385-1314 .- 1573-0867. ; 91, s. 119-129
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen (N) recycling to the regrowth of mulched red clover (Trifolium pratense L.) and mulched mixed red clover/perennial ryegrass (Lolium perenne L.) leys was determined in field experiments during three consecutive years using (15)N-labelled shoot material. Nitrogen recycling was greater in the pure clover stands than in the mixed stands in the beginning of the growing season, but increased successively in the mixed stands so that it was similar (14-15.5%) in both stands at the end of the season. This recycling of N from the mulch led to increased biomass accumulation but did not alter stand composition in the mixed stands. Mulch-derived N was incorporated into the soil organic N in both pure clover and mixed stands which thus contributed to building up soil fertility. An approximately similar proportion of N remained unaccounted for in mulched pure clover and mixed stand leys and presumably represented gaseous losses. To exploit the benefits of green manure leys in the humid temperate zone while minimising the negative environmental impact, these should be harvested rather than mulched.
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| 6. |
- Djodjic, Faruk, et al.
(författare)
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Soils potentially vulnerable to phosphorus losses : speciation of inorganic and organic phosphorus and estimation of leaching losses
- 2023
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Ingår i: Nutrient Cycling in Agroecosystems. - : Springer. - 1385-1314 .- 1573-0867. ; 127, s. 225-245
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Tidskriftsartikel (refereegranskat)abstract
- Eutrophication is an important threat to aquatic ecosystems world-wide, and reliable identification of areas vulnerable to phosphorus (P) losses from diffuse sources is essential for high efficiency of mitigation measures. In this three-step study we investigated (i) relationships between the agronomic (Olsen-P and P-AL) and environmental soil P tests (P-CaCl2) with molecular techniques (P-31 NMR and XANES) followed by (ii) rainfall simulation experiment on topsoil lysimeters and (iii) comparison to long-term field measurements of water quality. Soil samples were collected from seven sites indicated to be vulnerable to nutrient losses due to underlying geology. High P release correlated to standard agronomic P tests (Olsen P, r = 0.67; and P-AL, r = 0.74) and low P sorption capacity (r = - 0.5). High content of iron-bound P compounds indicated more labile P and higher release of dissolved P (r = 0.67). The leaching experiment showed that three out of four soils with high initial soil P status had both higher P leaching concentrations before fertilization (0.83-7.7 mg P l(-1)) compared to soil with low initial soil P status (0.007-0.23 mg P l(-1)), and higher increase in P concentrations after fertilization. Higher soil P sorption capacity reduced P leaching losses. Finally, long-term monitoring data show no significant trends in P losses in a field with low initial P content and moderate P fertilization rates whereas high and over time increasing P losses were recorded in a field with high initial soil P content and repetitively high P fertilization rates.
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| 7. |
- Einarsson, Rasmus, 1988, et al.
(författare)
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Nitrogen flows on organic and conventional dairy farms: a comparison of three indicators
- 2018
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Ingår i: Nutrient Cycling in Agroecosystems. - : Springer Science and Business Media LLC. - 1385-1314 .- 1573-0867. ; 110:1, s. 25-38
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Tidskriftsartikel (refereegranskat)abstract
- This paper analyzes nitrogen (N) flows on organic and conventional dairy farms in Sweden, and compares three indicators for the N pollution associated with the milk: (1) the farm-gate N surplus, (2) the chain N surplus, and (3) the N footprint. We find that, compared to indicators based on N surplus, the N footprint is a more understandable indicator for the N pollution associated with a product. However, the N footprint is not a replacement for the often-used farm-gate N surplus per unit area, since the two indicators give different information. An uncertainty analysis shows that, despite the large dataset, 1566 conventional and 283 organic farms, there is substantial uncertainty in the indicator values, of which a large part is due to possible bias in estimates of biological N fixation (BNF). Hence, although the best estimate is that conventional milk has 10–20% higher indicator values than organic, it is conceivable that improved estimates of BNF will change that conclusion. All three indicators simplify reality by aggregating N flows over time and space, and of different chemical forms. Thus, they hide many complexities with environmental relevance, which means that they can be misleading for decision-makers. This motivates further research on the relation between N surpluses and N footprints, and actual environmental damages.
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| 8. |
- Einarsson, Rasmus, 1988, et al.
(författare)
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Subnational nutrient budgets to monitor environmental risks in EU agriculture: calculating phosphorus budgets for 243 EU28 regions using public data
- 2020
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Ingår i: Nutrient Cycling in Agroecosystems. - : Springer Science and Business Media LLC. - 1573-0867 .- 1385-1314. ; 117:2, s. 199-213
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a method to estimate soil surface phosphorus (P) budgets for 243 subnational regions in EU28. This is about the maximum spatial resolution that can be achieved mainly using international datasets that are regularly updated. Similar subnational budgets could be established for nitrogen (N) with some additions to this method. Increasing the spatial resolution from national to subnational is one way to address the well-known issue that national nutrient budgets sometimes mask considerable heterogeneity, i.e., regional surpluses and deficits that are not seen in national averages. Our results indeed show how a rich structure of different P budgets emerges when moving from national to subnational level. Another approach is to exclude the most extensively managed areas from the budgets, to better represent the surplus in intensive agriculture areas. Here, we show that both approaches are useful and sometimes important as they can affect P surplus estimates by about 10 kg P ha− 1 y− 1 or more. The choice of spatial resolution is a trade-off between accuracy and precision. National budgets are the most accurate thanks to good data coverage, but they sometimes fail to identify considerable P surpluses and deficits at subnational level. Increasing the precision (spatial resolution) gradually reveals this heterogeneity but comes at the cost of growing data gaps, which we discuss in detail. These subnational P surpluses represent a middle ground which may prove useful as one indicator among others to monitor the development of environmental risks and resource problems over time.
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| 9. |
- Hamnér, Karin, et al.
(författare)
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Trace element concentrations in cereal grain of long-term field trials with organic fertilizer in Sweden
- 2015
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Ingår i: Nutrient cycling in agroecosystems. - : Springer Science and Business Media LLC. - 1385-1314 .- 1573-0867. ; 103, s. 347-358
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Tidskriftsartikel (refereegranskat)abstract
- Long-term use of organic fertilizers can lead to slow accumulation of trace elements in arable soil, whereas cropping systems with no return of organic residues to soil can lead to depletion. These changes in soil concentrations may potentially influence crop uptake of both essential and toxic metals over time. The aim of this study was to investigate the long-term use of manure and sewage sludge on trace element composition of cereal grain samples from on-going field experiments. The analyses showed that the organic fertilizers had limited or no impact on grain concentrations of cadmium (Cd), copper (Cu), manganese (Mn), molybdenum (Mo) and selenium (Se). Concentrations of these metals in grain remained low to moderate. However, application of the organic residues resulted in higher grain concentrations of zinc (Zn) at several locations, although results for different sites were contradictory. It was concluded that added trace metals present in organic fertilizer are not easily available to crops and that changes in soil properties, such as pH, and root proliferation often are of greater importance for crop uptake. Application of sewage sludge with a low Cd content to agricultural soil does not pose a high risk of increased Cd concentrations in crops. At low Cd concentrations as in Swedish arable soils, the Cd:Zn ratio seems to have little importance at low to moderate input of Cd and Zn.
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| 10. |
- Henryson, Kajsa, et al.
(författare)
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Environmental performance of crop cultivation at different sites and nitrogen rates in Sweden
- 2019
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Ingår i: Nutrient Cycling in Agroecosystems. - : SPRINGER. - 1385-1314 .- 1573-0867. ; 114:2, s. 139-155
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen (N) fertilisation has positive and negative effects on the environmental impact of crop cultivation. The mechanisms governing these effects are highly site-dependent, a factor often ignored in assessments of the environmental impact of crop cultivation. By assessing outputs of crop rotations using a life cycle approach, this study explored how greenhouse gas emissions and marine eutrophication caused by crop cultivation (including upstream processes such as production of farm inputs) depend on fertiliser rate and the site at which the cultivation occurs. Cereal unit (CU) was used as the functional unit. The calculations were based on data from multi-site long-term field experiments in Sweden and site-dependent data and models for non-measured processes. Cultivation at three N levels was evaluated, where the highest N rate was close to current average practices and the lowest level corresponded to one-third of that. Site characteristics had a stronger influence on both greenhouse gas emissions and marine eutrophication (variations of up to 330% and 490%, respectively, within N levels) than N level (variations of up to 74% and 59%, respectively, within sites). Main sources of variation in greenhouse gas emissions were soil nitrous oxide emissions (58-810g CO2eqCU-1) and soil organic carbon changes (14-720g CO2eqCU-1), while variations in marine eutrophication were mainly explained by field-level waterborne N losses (0.9-8.2g NeqCU-1). The large variation between sites highlights the importance of considering site characteristics when assessing the environmental impact of crop cultivation and evaluating the environmental consequences of crop management practices.
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