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| Registros recuperados: 54 | |
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| Melander, B.; Olesen, J.E.. |
| Weed problems can constrain organic crop production resulting in significant losses in yield and quality. Especially perennial weed species such as Elytrigia repens, Cirsium arvense and Tussilago farfara are posing problems as arable cropping systems do not hamper their vegetative proliferation sufficiently. Annual weeds may also reach unacceptable infestation levels leaving the growers with poor yielding crops and severe future weed problems owing to the shedding and spread of weed seeds. Effective weed management is a key component for successful organic crop production and a prerequisite to increase the yielding potential of many organic crop production systems. Weed problems are most severe on stockless arable farms because the supply of nutrients can... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Crop combinations and interactions; Weed management. |
| Ano: 2013 |
URL: http://orgprints.org/24550/1/24550.pdf |
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| Chirinda, N.; Carter, M.S; Albert, K.R.; Ambus, P.; Olesen, J.E.; Porter, J.R.; Petersen, S.O.. |
| Conventional cropping systems rely on targeted short-term fertility management, whereas organic systems depend, in part, on long-term increase in soil fertility as determined by crop rotation and management. Such differences influence soil nitrogen (N) cycling and availability through the year. The main objective of this study was to compare nitrous oxide (N2O) emissions from soil under winter wheat (Triticum aestivum L.) within three organic and one conventional cropping system that differed in type of fertilizer, presence of catch crops and proportion of N2-fixing crops. The study was replicated in two identical long-term crop rotation experiments on sandy loam soils under different climatic conditions in Denmark (Flakkebjerg–eastern Denmark and... |
| Tipo: Journal paper |
Palavras-chave: Farming Systems; Air and water emissions; Environmental aspects. |
| Ano: 2010 |
URL: http://orgprints.org/18510/1/chirinda_et_al_2010_%28N2O%29.pdf |
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| Chatskikh, D.; Olesen, J.E.; Berntsen, J.; Regina, K.; Yamulki, S.. |
| Nitrous oxide (N2O) is a potent greenhouse gas with a high contribution from agricultural soils and emissions that depend on soil type, climate, crops and management practices. The N2O emissions therefore need to be included as an integral part of environmental assessment of agricultural production systems. A dynamical algorithm for N2O production and emission from agricultural soils was developed and included in the FASSET whole-farm model. The model simulated carbon and nitrogen (N) turnover on a daily basis. Both nitrification and denitrification was included in the model as sources for N2O production, and the N2O emissions were simulated to depend on soil microbial and physical conditions. The model was tested on experimental data of N2O emissions from... |
| Tipo: Journal paper |
Palavras-chave: Pasture and forage crops; Air and water emissions. |
| Ano: 2005 |
URL: http://orgprints.org/1808/2/1808.pdf |
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| Petersen, B.M.; Berntsen, J.; Kristensen, I.S.; Olesen, J.E.. |
| I forbindelse med den faglige evaluering forud for Vandmiljøplan II (VMP II) blev det anslået, at økologisk jordbrug i gennemsnit reducerede udvaskningen med 10 kg kvælstof (N) per ha. Det fremgik, at dette tal var behæftet med stor usikkerhed. Da der i forbindelse med genberegning af udvaskningsniveauet fra dansk landbrug i 2002 skete en opjustering af det generelle udvaskningsniveau før VMP II, vurderedes dette ikke at skulle ske for økologisk jordbrug. Forskellen i nitratudvaskning mellem økologiske og konventionelle arealer blev derfor revurderet til at være 28 kg N per ha.DJF har nu genanalyseret forskellene mellem økologiske og konventionelle planteavlsbrug for repræsentative sædskifter, driftsledelser og gødningsimport (Berntsen et al., 2004).... |
| Tipo: Journal paper |
Palavras-chave: Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/4663/1/4663.PDF |
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| Berntsen, J.; Petersen, B.M.; Kristensen, I.S.; Olesen, J.E.. |
| Med udgangspunkt i regnskabsdata fra Fødevareøkonomisk Institut (FØI) og data fra Centrale Registre (CR) blev importen af kvælstof (N) i gødning til marken til konventionelle og økologiske planteavlere estimeret til hhv. 129 og 51 kg N ha-1 år-1. Desuden blev der med udgangspunkt i den aktuelle afgrødefordeling opstillet et generelt sædskifte for hver af de to systemer. Det opstillede sædskifte for den økologiske planteavl havde en høj andel af vårsæd og desuden 20% kløvergræs, mens den konventionelle planteavl var domineret af kornafgrøder primært i form af vintersæd. Med baggrund i disse model-sædskifter blev N-balancen på markniveau beregnet ved anvendelse af FASSET modellen. Dette inkluderede også N-udvaskning og ændring i jordens N-pulje. Alle... |
| Tipo: Report |
Palavras-chave: Nutrient turnover; Soil; Soil biology; Soil quality; Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/4653/1/4653.pdf |
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| Olesen, J.E.; Sørensen, P.; Thomsen, I.K.; Eriksen, J.; Thomsen, A.G.; Berntsen, J.. |
| Cycling of N in agriculture through the use of mineral fertilizers, manures and N-fixing crops gives rise to many forms of N emissions to the environment, including nitrate (NO3) leaching, ammonia (NH3) volatilization and nitrous oxide (N2O) emissions, resulting in ground water pollution, eutrophication of surface waters, soil acidification and contributions to global warming. The high rates of N input in intensive North European agricultural systems have given rise to high loss rates, and the focus in Danish agriculture during the past two decades has been on increasing the N use efficiency with the aim of reducing losses. The N use efficiency at the system level can be increased by improved handling of manure, targeted application of fertilizers and... |
| Tipo: Book chapter |
Palavras-chave: Nutrient turnover. |
| Ano: 2004 |
URL: http://orgprints.org/4668/3/4668.pdf |
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| Thomsen, I. K.; Schjønning, P.; Olesen, J.E.; Christensen, B. T.. |
| The turnover of native and applied C and N in undisturbed soil samples of different texture but similar mineralogical composition, origin and cropping history was evaluated at –10 kPa water potential. Cores of structurally intact soil with 108, 224 and 337 g clay kg-1 were horizontially sliced and 15N-labelled sheep faeces was placed between the two halves of the intact core. The cores together with unamended treatments were incubated in the dark at 20°C and the evolution of CO2-C determined continuously for 177 d. Inorganic and microbial biomass N and 15N were determined periodically. Net nitrification was less in soil amended with faeces compared with unamended soil. When adjusted for the NO3-N present in soil before faeces was applied, net nitrification... |
| Tipo: Journal paper |
Palavras-chave: Nutrient turnover. |
| Ano: 2003 |
URL: http://orgprints.org/272/1/HarmTaskArev.doc |
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| Vinther, F.P.; Hansen, E.M.; Olesen, J.E.. |
| The impacts of crop rotation and input of organic matter in the form of green manure crops, straw residues and incorporation of catch crops on crop yield, nitrogen uptake, microbial biomass and activity was studied in unfertilised crop rotations differing in input of plant residues, i.e. high-input rotations with a grass-clover crop and catch crops included and low-input cereal rotations without catch crops. The parameters studied included substrate induced respiration (SIR), hydrolysis of fluorescein diacetate (FDA), arylsulfatase activity (ASA), N mineralisation, N2O emission, and soil respiration. These parameters were measured in bare soil plots, to estimate the effects of previous years crops and input of plant residues. In neighbouring plots crop... |
| Tipo: Journal paper |
Palavras-chave: Nutrient turnover; Soil biology; Soil quality; Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/4012/1/Vinther%2C_Hansen_Olesen_2004.pdf |
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| Dalgaard, R.; Olesen, J.E.; Halberg, N.; Berntsen, J.. |
| De sædskiftemæssige aspekter af energiproduktion i økologisk jordbrug er belyst ved anvendelse af to forskellige tilgangsvinkler ved hjælp af henholdsvis bedriftsmodellen FASSET anvendt på markniveau og ved hjælp af en livscyklusanalyse (LCA) på bedriftsniveau. FASSET-modellen giver mulighed for at vurdere effekter af anvendelse af kløvergræs til biogas på afgrødeudbytte og på miljøeffekter (kvælstofudvaskning og drivhusgasemissioner fra marken). LCA-analyserne giver mulighed for at vurdere effekter på energiproduktion sammenholdt med øvrige kilder til drivhusgasemissioner, herunder emissionerne fra energiforbrug og indkøbt foder. I beregningerne med FASSET-modellen er der taget udgangspunkt i et rent planteavlssædskifte til økologisk jordbrug. I dette... |
| Tipo: Report chapter |
Palavras-chave: Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/4674/1/4674.doc |
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| Johansen, A.; Hauggaard-Nielsen, H.; Ambus, P.; Dalgaard, T.; Jørgensen, U.; Nielsen, A.M.; Nielsen, L.H.; Olesen, J.E.; Roepstorff, A.; Skytte, K.; Smith, J.E.; Thomsen, A.B.; Carter, M.S.; Jensen, E.S.. |
| Production of bioenergy in organic agriculture may be implemented in the future to reduce the reliance on non-renewable fossil fuels and minimize greenhouse gas (GHG) emissions. Therefore it is important to assess the potential effect this may have on soil quality and biological parameters. This project aims at designing and evaluate a combined concept for biomass and bio-energy production in OA, while considering soil bio-geo-chemical cycling of plant nutrients and biodiversity of the soil microbiota. |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Nutrient turnover; Soil biology; Biodiversity and ecosystem services; Soil quality; Air and water emissions; Farm economics; Farm nutrient management; Quality and evaluation of inputs. |
| Ano: 2008 |
URL: http://orgprints.org/15157/1/15157.pdf |
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| Olesen, J.E.; Petersen, B.M.. |
| The Kyoto Protocol allows carbon sequestration from changes in agricultural land use to be a mechanism for reducing anthropogenic greenhouse gas emissions. There is a specific requirement in the protocol for verification of the sequestration estimates, which may often involve the use of soil carbon simulation models and thus puts a large requirement on the validity of these models. The commonly used soil organic matter models have been calibrated on the basis of measurements of topsoil C contents under the implicit assumption that there is negligible vertical transport of soil C. We demonstrate this assumption to be wrong, and that it may lead to large deviations when modelling long-term soil organic matter development. Therefore a model with a net... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Nutrient turnover. |
| Ano: 2004 |
URL: http://orgprints.org/4670/1/4670.doc |
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| Schjønning, P.; Munkholm, L.J.; Elmholt, S.; Olesen, J.E.. |
| Management-induced depletion in soil organic carbon (SOC) may create critical tilth conditions for arable farming. We investigated the short-term effect of crop rotation and addition of animal manure on SOC fractions, the dispersibility of soil clay, the length of fungal hyphae, wet aggregate stability, tensile strength of dry aggregates, and the pore size distribution, gas diffusivity and permeability of undisturbed bulk soil. SOC fractions were measured in whole-soil samples and in 1-2 mm air-dried aggregates. Plough layer soil was sampled five and six years after the start of a field experiment with different cropping systems at two loamy sand soils (Foulum, ~9% clay and Flakkebjerg, ~14% clay). A soil drop test was performed in the field to evaluate in... |
| Tipo: Journal paper |
Palavras-chave: Crop combinations and interactions; Soil biology; Soil quality; Soil tillage; Composting and manuring. |
| Ano: 2007 |
URL: http://orgprints.org/7750/1/7750.pdf |
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| Vinther, F.P.; Hansen, E.M.; Olesen, J.E.. |
| The impacts of crop rotation and input of organic matter in the form of straw residues and incorporation of catch crops on crop yield, nitrogen uptake and microbial biomass and activity was studied in a field experiment initiated in 1996 at Research Centre Foulum. The parameters studied included substrate-induced respiration (SIR) from where microbial biomass C was calculated, hydrolysis of fluorescein diacetate (FDA), arylsulfatase activity (ASA), N mineralisation, N2O emission, and soil respiration. These experiments were carried out in bare soil plots to measure the effects of previous crops and input of organic matter. In 2001 measurements were carried out in four treatments where the crops in 2000 were winter wheat (W-w), pea-barley (P-b),... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Nutrient turnover Soil quality Production systems Soil biology Air and water emissions Cereals; Pulses and oilseeds. |
| Ano: 2002 |
URL: http://orgprints.org/1790/1/Finn_Vinther_abstract.doc |
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| Noe, E.; Sørensen, P.; Melander, B.; Olesen, J.E.; Fog, E.. |
| There is a gap between the scientific idea of robust and economically viable organic arable farming systems with optimized crop rotations for nutrient and pest management and how these systems look like in practice. In order to explore this gap, we visited and interviewed ten organic arable farms in Denmark. Our main findings are: 1) Organic arable farming operates in a very dynamic and changing environment in terms of prizing and market opportunities, and the main focus of the farm managements was the coping strategy within this changing environment; 2) The farming systems were continuously changing and developing, buying and renting more land, changing manure agreements and other forms of cooperation and arrangements; 3) Short term profit was paid much... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Markets and trade; Research communication and quality. |
| Ano: 2013 |
URL: http://orgprints.org/24578/1/24578.pdf |
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| Dalgaard, Tommy; Hutchings, Nicholas J.; Dragosits, U.; Olesen, J.E.; Kjeldsen, Chris; Drouet, J.L.; Cellier, P.. |
| The aim of this study is to illustrate the importance of farm scale heterogeneity on nitrogen (N) losses in agricultural landscapes. Results are exemplified with a chain of N models calculating farm-N balances and distributing the N-surplus to N-losses (volatilisation, denitrification, leaching) and soil-N accumulation/release in a Danish landscape. Possible non-linearities in upscaling are assessed by comparing average model results based on (i) individual farm level calculations and (ii) averaged inputs at landscape level. Effects of the non-linearities that appear when scaling up from farm to landscape are demonstrated. Especially in relation to ammonia losses the non-linearity between livestock density and N-loss is significant (p > 0.999), with... |
| Tipo: Journal paper |
Palavras-chave: Air and water emissions; Landscape and recreation; Farm nutrient management. |
| Ano: 2011 |
URL: http://orgprints.org/19043/4/19043.pdf |
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| Rasmussen, I.A.; Askegaard, M.; Olesen, J.E.. |
| Catch crops reduced nitrate leaching in both rotations at Jyndevad. The same tendency was seen in one rotation at Flakkebjerg. At Jyndevad, stubble cultivations decreased Elymus repens density in the treatments without catch crops. Application of manure decreased the E. repens density in one rotation. At Flakkebjerg, there was a lower infestation of C. arvense in the rotation with than without grass-clover, with least biomass in the crop the year after grass-clover. There was no significant difference between the biomass of C. arvense in the treatments with and without catch crop, in spite of the fact that stubble cultivations and row hoeing were carried out without catch crops. The reason was most likely that the nutrients retained in the topsoil by the... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Crop combinations and interactions; Weed management. |
| Ano: 2007 |
URL: http://orgprints.org/11346/1/abs_6.1_Ilse_Rasmussen.doc |
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| Rasmussen, I.A.; Askegaard, M.; Olesen, J.E.. |
| Long-term control of perennial weeds create a challenge in organic farming, especially in ar-able farming. Perennial weeds are most often controlled by tillage, often stubble tillage after harvest of cereals or short-term tillage during the summer (Melander et al., 2005). Tillage leads to increased leaching of nutrients (Askegaard et al., 2005), which is unacceptable for the environment and in turn renders the succeeding crop less competitive compared to the peren-nial weeds – thus initiating a vicious circle. |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Crop combinations and interactions; Weed management. |
| Ano: 2007 |
URL: http://orgprints.org/11349/1/NJF07_10_Rasmussen2.doc |
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| Registros recuperados: 54 | |
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