Kristian Kristensen | Aarhus University (original) (raw)

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Research paper thumbnail of Physical destruction of the sprouting ability of Elytrigiarepens rhizome buds

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Research paper thumbnail of Determination of Fungicide Residues in Field-Grown Strawberries following Different Fungicide Strategies against Gray Mold ( Botrytis cinerea )

Journal of Agricultural and Food Chemistry, 2006

In a 2 year experiment, residues in field-grown strawberries were investigated from the fungicide... more In a 2 year experiment, residues in field-grown strawberries were investigated from the fungicides fenhexamid, pyrimethanil, tolylfluanid, and kresoxim-methyl resulting from different strategies, as regards the dose, number, and time of fungicide applications. Kresoxim-methyl was only used the first year and in full or no dose to control powdery mildew. In the first year, the highest concentrations analyzed were 0.66 mg kg(-1) for pyrimethanil and 0.63 mg kg(-1) for fenhexamid resulting from the use of recommended dose rates and a preharvest interval (PHI) of 10 days, thus not exceeding the Danish maximum residue limit (MRL) of 1 mg kg(-1). Tolylfluanid was used no later than 21 days before harvest, which left residue contents in the berries of 0.48 mg kg(-1), a value well below the MRL of 5 mg kg(-1). In the second year, fungicide residues found in the samples were generally lower, 0.39 and 0.03 mg kg(-1) for pyrimethanil and fenhexamid, respectively. No residues of kresoxim-methyl were found in any of the samples from the field trials, indicating that kresoxim-methyl residues had declined to a level well below the detection limit within the 28 day period between the last application and the harvest.

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Research paper thumbnail of NJF Seminar 438: Significant effects of the machine wheel load on grass yield by using a new field expermental method

NJF Report, 2010

... 2 Sensors based on soil electrical properties..... 3 Mapping variation in soil and plant prop... more ... 2 Sensors based on soil electrical properties..... 3 Mapping variation in soil and plant properties in Norway–Experiences from the last decade.. 9 Application of EM sensors in archaeology: EM survey at the manor Nr. Vosborg, Denmark.... ...

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Research paper thumbnail of The effects of strawberry cropping practices on the strawberry tortricid (Lepidoptera: Tortricidae), its natural enemies, and the presence of nematodes

Journal of insect science (Online), 2014

Cropping practice can affect pests and natural enemies. A three-year study of the strawberry tort... more Cropping practice can affect pests and natural enemies. A three-year study of the strawberry tortricid, Acleris comariana (Lienig and Zeller) (Lepidoptera: Tortricidae), its parasitoid Copidosoma aretas Walker (Hymenoptera: Encyrtidae), and its entomopathogenic fungi was conducted in seven pairs of organic and conventional farms to test the hypothesis that farming practice (organic versus conventional) will affect the level of pest infestation and will affect the natural enemies. In addition, the number of years with strawberries on the farm, field age, and other factors that may affect pests and their natural enemies were considered. Farms were characterized by their cropping practices, cropping history, and other parameters. Field-collected larvae were laboratory reared to assess mortality from parasitoids and entomopathogenic fungi. In 2010, a survey of nematodes was made to assess the response of an unrelated taxonomic group to cropping practice. 2,743 larvae were collected. Of ...

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Research paper thumbnail of Buffer zones for biodiversity of plants and arthropods: is there a compromise on width?

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Research paper thumbnail of Hjulbelastning og dæktryks påvirkning af græsudbyttet

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Research paper thumbnail of Simulation of vegetation cover on sidewalks in Denmark

Pest Management Science, 2004

Data from five 3-year experiments comparing different strategies of non-chemical weed control wer... more Data from five 3-year experiments comparing different strategies of non-chemical weed control were analysed in order to set up a model that could be used for simulating further strategies. The treatments included different frequencies and effects of weed control using flaming, steaming and weed brushing. Each plot consisted of about 100 m of sidewalk. The amount of weed on the sidewalks was recorded several times during the 3-year period using a system of cameras mounted on a Terrain Vehicle moving on the sidewalk and post processing using image analyses of extracted images. The percentage of sidewalk covered by weed was estimated on the basis of the image analyses. The model used for describing the weed coverage comprises three components. The first component describes the growth of weeds; the second describes reduction caused by wearing and decay of weeds in the autumn and the third describes the reduction caused by weed control using weed brushing, steaming and flaming. The parameters of the model were estimated from the data for later use for simulating additional strategies.

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Research paper thumbnail of Annual emissions of CH<sub>4</sub> and N<sub>2</sub>O, and ecosystem respiration, from eight organic soils in Western Denmark managed by agriculture

Biogeosciences, 2012

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Research paper thumbnail of Methodology for a labour extensive and semi-automated field trial design using autoguidance and conventional machinery

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Research paper thumbnail of Predicting spring barley yield from variety-specific yield potential, disease resistance and straw length, and from environment-specific disease loads and weed pressure

Euphytica, 2008

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Research paper thumbnail of Annual emissions of CH4 and N2O, and ecosystem respiration, from eight organic soils in Western Denmark managed by agriculture

Biogeosciences, 2012

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Research paper thumbnail of Predicting spring barley yield from variety-specific yield potential, disease resistance and straw length, and from environment-specific disease loads and weed pressure

Euphytica, 2008

For low-input crop production, well-characterised varieties increase the possibilities of managin... more For low-input crop production, well-characterised varieties increase the possibilities of managing diseases and weeds. This analysis aims at developing a framework for analyzing grain yield using external varietal information about disease resistance, weed competitiveness and yield potential and quantifying the impact of susceptibility grouping and straw length scores (as a measure for weed competitiveness) for predicting spring barley grain yield

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Research paper thumbnail of Winter wheat yield response to climate variability in Denmark

The Journal of Agricultural Science, 2011

... 2002). Tem-perature affects crop yield through effects on growth rate and on plant developmen... more ... 2002). Tem-perature affects crop yield through effects on growth rate and on plant development. At low temperatures (c. &amp;amp;amp;lt;10°C), both photosynthesis and plant sink strength would be restricted by temperatures (Gavito et al. 2001 ...

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Research paper thumbnail of Whole-rotation dry matter and nitrogen grain yields from the first course of an organic farming crop rotation experiment

The Journal of Agricultural Science, 2002

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Research paper thumbnail of Simulation of vegetation cover on sidewalks in Denmark

Pest Management Science, 2004

Data from five 3-year experiments comparing different strategies of non-chemical weed control wer... more Data from five 3-year experiments comparing different strategies of non-chemical weed control were analysed in order to set up a model that could be used for simulating further strategies. The treatments included different frequencies and effects of weed control using flaming, steaming and weed brushing. Each plot consisted of about 100 m of sidewalk. The amount of weed on the sidewalks was recorded several times during the 3-year period using a system of cameras mounted on a Terrain Vehicle moving on the sidewalk and post processing using image analyses of extracted images. The percentage of sidewalk covered by weed was estimated on the basis of the image analyses. The model used for describing the weed coverage comprises three components. The first component describes the growth of weeds; the second describes reduction caused by wearing and decay of weeds in the autumn and the third describes the reduction caused by weed control using weed brushing, steaming and flaming. The parameters of the model were estimated from the data for later use for simulating additional strategies.

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Research paper thumbnail of Strategies for non-chemical weed control on public paved areas in Denmark

Pest Management Science, 2004

To be proactive in minimizing pesticide use, the public authorities in Denmark agreed in 1998 to ... more To be proactive in minimizing pesticide use, the public authorities in Denmark agreed in 1998 to phase out the use of pesticides on publicly owned areas by the end of 2002. A part of the agreement was an increasing focus on research into and development of new methods and implements for non-chemical weed control on paved areas. Due to a large increase in the costs of non-chemical weed control, the park authorities have to put the different types and locations of paved areas in order of priority to optimize the weed control effort. The present authors divided the paved areas into five weed control levels, dependent on placement, quality and use. For the 3 years 1999-2001, experiments with different non-chemical weed control methods were conducted on pavements at six locations in Denmark. The aim was to test the reaction of the weeds to different treatments and strategies. The efficacies of the methods were evaluated by analysis of digital images to estimate the fraction of the paved area covered with green vegetation (weed coverage). The weed coverage was used as the dependent variable in the subsequent statistical analysis. The independent variables in the model were incoming radiation, wear, area of joints in the pavement, the dying process of the weeds and the number of runs/applied energy of the mechanical or thermal weed control methods, respectively. The estimated parameters from the statistical model were used to build a simulation model, which was used to optimise five weed control strategies to fulfil the suggested weed control levels. In the suggested strategy for maximum weed control, 12 thermal weeding applications at 2-week intervals are suggested. The &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;clean-up&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; strategy is based on one weed-brushing in late spring or early autumn.

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Research paper thumbnail of Time for a shift in crop production: embracing complexity through diversity at all levels

Journal of the Science of Food and Agriculture, 2009

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Research paper thumbnail of Relating soil microbial activity to water content and tillage-induced differences in soil structure

Geoderma, 2011

Several studies have identified optima in soil water content for aerobic microbial activity, and ... more Several studies have identified optima in soil water content for aerobic microbial activity, and this has been ascribed to a balance between gas and solute diffusivity as limiting processes. We investigated the role of soil structure, as created by different tillage practices (moldboard ploughing, MP, or shallow tillage, ST), in regulating net nitrification, applied here as an index of aerobic

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Research paper thumbnail of Turnover of organic matter in differently textured soils

Geoderma, 1999

Soil type effects on organic matter turnover are most often ascribed directly to differences in s... more Soil type effects on organic matter turnover are most often ascribed directly to differences in soil clay content. Since soil texture determines the physical characteristics of soil, aggregation and water holding capacity may be more relevant to address in the search for ...

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Research paper thumbnail of Similarity of differently sized macro-aggregates in arable soils of different texture

Geoderma, 2006

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Research paper thumbnail of Physical destruction of the sprouting ability of Elytrigiarepens rhizome buds

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Determination of Fungicide Residues in Field-Grown Strawberries following Different Fungicide Strategies against Gray Mold ( Botrytis cinerea )

Journal of Agricultural and Food Chemistry, 2006

In a 2 year experiment, residues in field-grown strawberries were investigated from the fungicide... more In a 2 year experiment, residues in field-grown strawberries were investigated from the fungicides fenhexamid, pyrimethanil, tolylfluanid, and kresoxim-methyl resulting from different strategies, as regards the dose, number, and time of fungicide applications. Kresoxim-methyl was only used the first year and in full or no dose to control powdery mildew. In the first year, the highest concentrations analyzed were 0.66 mg kg(-1) for pyrimethanil and 0.63 mg kg(-1) for fenhexamid resulting from the use of recommended dose rates and a preharvest interval (PHI) of 10 days, thus not exceeding the Danish maximum residue limit (MRL) of 1 mg kg(-1). Tolylfluanid was used no later than 21 days before harvest, which left residue contents in the berries of 0.48 mg kg(-1), a value well below the MRL of 5 mg kg(-1). In the second year, fungicide residues found in the samples were generally lower, 0.39 and 0.03 mg kg(-1) for pyrimethanil and fenhexamid, respectively. No residues of kresoxim-methyl were found in any of the samples from the field trials, indicating that kresoxim-methyl residues had declined to a level well below the detection limit within the 28 day period between the last application and the harvest.

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Research paper thumbnail of NJF Seminar 438: Significant effects of the machine wheel load on grass yield by using a new field expermental method

NJF Report, 2010

... 2 Sensors based on soil electrical properties..... 3 Mapping variation in soil and plant prop... more ... 2 Sensors based on soil electrical properties..... 3 Mapping variation in soil and plant properties in Norway–Experiences from the last decade.. 9 Application of EM sensors in archaeology: EM survey at the manor Nr. Vosborg, Denmark.... ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The effects of strawberry cropping practices on the strawberry tortricid (Lepidoptera: Tortricidae), its natural enemies, and the presence of nematodes

Journal of insect science (Online), 2014

Cropping practice can affect pests and natural enemies. A three-year study of the strawberry tort... more Cropping practice can affect pests and natural enemies. A three-year study of the strawberry tortricid, Acleris comariana (Lienig and Zeller) (Lepidoptera: Tortricidae), its parasitoid Copidosoma aretas Walker (Hymenoptera: Encyrtidae), and its entomopathogenic fungi was conducted in seven pairs of organic and conventional farms to test the hypothesis that farming practice (organic versus conventional) will affect the level of pest infestation and will affect the natural enemies. In addition, the number of years with strawberries on the farm, field age, and other factors that may affect pests and their natural enemies were considered. Farms were characterized by their cropping practices, cropping history, and other parameters. Field-collected larvae were laboratory reared to assess mortality from parasitoids and entomopathogenic fungi. In 2010, a survey of nematodes was made to assess the response of an unrelated taxonomic group to cropping practice. 2,743 larvae were collected. Of ...

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Research paper thumbnail of Buffer zones for biodiversity of plants and arthropods: is there a compromise on width?

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Hjulbelastning og dæktryks påvirkning af græsudbyttet

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Simulation of vegetation cover on sidewalks in Denmark

Pest Management Science, 2004

Data from five 3-year experiments comparing different strategies of non-chemical weed control wer... more Data from five 3-year experiments comparing different strategies of non-chemical weed control were analysed in order to set up a model that could be used for simulating further strategies. The treatments included different frequencies and effects of weed control using flaming, steaming and weed brushing. Each plot consisted of about 100 m of sidewalk. The amount of weed on the sidewalks was recorded several times during the 3-year period using a system of cameras mounted on a Terrain Vehicle moving on the sidewalk and post processing using image analyses of extracted images. The percentage of sidewalk covered by weed was estimated on the basis of the image analyses. The model used for describing the weed coverage comprises three components. The first component describes the growth of weeds; the second describes reduction caused by wearing and decay of weeds in the autumn and the third describes the reduction caused by weed control using weed brushing, steaming and flaming. The parameters of the model were estimated from the data for later use for simulating additional strategies.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Annual emissions of CH<sub>4</sub> and N<sub>2</sub>O, and ecosystem respiration, from eight organic soils in Western Denmark managed by agriculture

Biogeosciences, 2012

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Methodology for a labour extensive and semi-automated field trial design using autoguidance and conventional machinery

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Predicting spring barley yield from variety-specific yield potential, disease resistance and straw length, and from environment-specific disease loads and weed pressure

Euphytica, 2008

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Annual emissions of CH4 and N2O, and ecosystem respiration, from eight organic soils in Western Denmark managed by agriculture

Biogeosciences, 2012

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Predicting spring barley yield from variety-specific yield potential, disease resistance and straw length, and from environment-specific disease loads and weed pressure

Euphytica, 2008

For low-input crop production, well-characterised varieties increase the possibilities of managin... more For low-input crop production, well-characterised varieties increase the possibilities of managing diseases and weeds. This analysis aims at developing a framework for analyzing grain yield using external varietal information about disease resistance, weed competitiveness and yield potential and quantifying the impact of susceptibility grouping and straw length scores (as a measure for weed competitiveness) for predicting spring barley grain yield

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Winter wheat yield response to climate variability in Denmark

The Journal of Agricultural Science, 2011

... 2002). Tem-perature affects crop yield through effects on growth rate and on plant developmen... more ... 2002). Tem-perature affects crop yield through effects on growth rate and on plant development. At low temperatures (c. &amp;amp;amp;lt;10°C), both photosynthesis and plant sink strength would be restricted by temperatures (Gavito et al. 2001 ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Whole-rotation dry matter and nitrogen grain yields from the first course of an organic farming crop rotation experiment

The Journal of Agricultural Science, 2002

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Simulation of vegetation cover on sidewalks in Denmark

Pest Management Science, 2004

Data from five 3-year experiments comparing different strategies of non-chemical weed control wer... more Data from five 3-year experiments comparing different strategies of non-chemical weed control were analysed in order to set up a model that could be used for simulating further strategies. The treatments included different frequencies and effects of weed control using flaming, steaming and weed brushing. Each plot consisted of about 100 m of sidewalk. The amount of weed on the sidewalks was recorded several times during the 3-year period using a system of cameras mounted on a Terrain Vehicle moving on the sidewalk and post processing using image analyses of extracted images. The percentage of sidewalk covered by weed was estimated on the basis of the image analyses. The model used for describing the weed coverage comprises three components. The first component describes the growth of weeds; the second describes reduction caused by wearing and decay of weeds in the autumn and the third describes the reduction caused by weed control using weed brushing, steaming and flaming. The parameters of the model were estimated from the data for later use for simulating additional strategies.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Strategies for non-chemical weed control on public paved areas in Denmark

Pest Management Science, 2004

To be proactive in minimizing pesticide use, the public authorities in Denmark agreed in 1998 to ... more To be proactive in minimizing pesticide use, the public authorities in Denmark agreed in 1998 to phase out the use of pesticides on publicly owned areas by the end of 2002. A part of the agreement was an increasing focus on research into and development of new methods and implements for non-chemical weed control on paved areas. Due to a large increase in the costs of non-chemical weed control, the park authorities have to put the different types and locations of paved areas in order of priority to optimize the weed control effort. The present authors divided the paved areas into five weed control levels, dependent on placement, quality and use. For the 3 years 1999-2001, experiments with different non-chemical weed control methods were conducted on pavements at six locations in Denmark. The aim was to test the reaction of the weeds to different treatments and strategies. The efficacies of the methods were evaluated by analysis of digital images to estimate the fraction of the paved area covered with green vegetation (weed coverage). The weed coverage was used as the dependent variable in the subsequent statistical analysis. The independent variables in the model were incoming radiation, wear, area of joints in the pavement, the dying process of the weeds and the number of runs/applied energy of the mechanical or thermal weed control methods, respectively. The estimated parameters from the statistical model were used to build a simulation model, which was used to optimise five weed control strategies to fulfil the suggested weed control levels. In the suggested strategy for maximum weed control, 12 thermal weeding applications at 2-week intervals are suggested. The &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;clean-up&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; strategy is based on one weed-brushing in late spring or early autumn.

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Research paper thumbnail of Time for a shift in crop production: embracing complexity through diversity at all levels

Journal of the Science of Food and Agriculture, 2009

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Relating soil microbial activity to water content and tillage-induced differences in soil structure

Geoderma, 2011

Several studies have identified optima in soil water content for aerobic microbial activity, and ... more Several studies have identified optima in soil water content for aerobic microbial activity, and this has been ascribed to a balance between gas and solute diffusivity as limiting processes. We investigated the role of soil structure, as created by different tillage practices (moldboard ploughing, MP, or shallow tillage, ST), in regulating net nitrification, applied here as an index of aerobic

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Turnover of organic matter in differently textured soils

Geoderma, 1999

Soil type effects on organic matter turnover are most often ascribed directly to differences in s... more Soil type effects on organic matter turnover are most often ascribed directly to differences in soil clay content. Since soil texture determines the physical characteristics of soil, aggregation and water holding capacity may be more relevant to address in the search for ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Similarity of differently sized macro-aggregates in arable soils of different texture

Geoderma, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Resilience and (in)security: Practices, subjects, temporalities

Diverse, sometimes even contradictory concepts and practices of resilience have proliferated into... more Diverse, sometimes even contradictory concepts and practices of resilience have proliferated into a wide range of security policies. In introducing this special issue, we problematize and critically discuss how these forms of resilience change environments, create subjects, link temporalities, and redefine relations of security and insecurity. We show the increased attention – scholarly as well as political – given to resilience in recent times and provide a review of the state of critical security studies literature on resilience. We argue that to advance this discussion, resilience needs to be conceptualized and investigated in plural terms. We use temporalities and subjectivities as key analytical aspects to investigate the plural instantiations of resilience in actual political practice. These two issues – subjectivity and temporality – form the overall context for the special issue and are core themes for all the articles collected here.

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