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| Registros recuperados: 17 | |
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| Pedersen, Anders; Zhang, Kefeng; Jensen, Lars Stoumann; Thorup-Kristensen, Kristian. |
| Plant soil and atmosphere models are commonly used to predict crop yield and associated environmental consequences. Such models often include complex modelling of water movement, soil organic matter turnover and above ground plant growth. However, the root modelling in these models is often very simple, partly due to a limited access to experimental data. Here we propose a root model developed to describe root growth, root density and nitrogen uptake. The model focuses on annual crops, and attempts to model root growth of different crop species and row crops and its significance for nitrogen uptake from different parts of the soil volume. |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Crop combinations and interactions; Biodiversity and ecosystem services. |
| Ano: 2007 |
URL: http://orgprints.org/10745/1/10745.pdf |
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| Pedersen, Anders; Zhang, Kefeng; Thorup-Kristensen, Kristian; Jensen, Lars Stoumann. |
| We present a 2-D model for simulation of root density and plant nitrogen (N) uptake for crops grown in agricultural systems, based on a modification of the root density equation originally proposed by Gerwitz and Page (1974). A root system form parameter was introduced to describe the distribution of root length vertically and horizontally in the soil profile. The form parameter can vary from 0 where root density is evenly distributed through the soil profile, to 8 where practically all roots are found near the surface. The root model has other components describing root features, such as specific root length and plant N uptake kinetics. The same approach is used to distribute root length horizontally, allowing simulation of root growth and plant N uptake... |
| Tipo: Journal paper |
Palavras-chave: Nutrient turnover; Farm nutrient management; Air and water emissions. |
| Ano: 2009 |
URL: http://orgprints.org/16106/1/16106.pdf |
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| Pedersen, Anders. |
| Oral presentation in working group 5: Buffer strips and catch crops: cosmetic or beneficial? In most countries sufficient knowledge of catch crops has been acquired by farmers to apply them as a basic element of "Good Agricultural Practice". Buffer strips seem less known and applied. Various contributions point at adverse effects, such as increase in N leaching on buffered fields, overloading of buffer capacity and increase in denitrification. Hence, a major question to be discussed is how buffer strips should be designed and managed to achieve the desired effects whilst avoiding or minimising adverse effects? Another question is to what extent buffer strips should be accompanied by other measures, such as catch crop cultivation. Convenors: Adrie van... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Nutrient turnover; Farm nutrient management. |
| Ano: 2005 |
URL: http://orgprints.org/7832/1/7832.pdf |
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| Pedersen, Anders; Thorup-Kristensen, Kristian; Kristensen, Hanne Lakkenborg; Berntsen, Jørgen. |
| Dynamic plant/soil models are used to predict crop production, N dynamics and nitrate leaching loss of different cropping systems. To do this, the models simulate various aspects of plant biology, soil biology and soil physics. Correct simulation of root growth is critical for the simulation of nitrate leaching losses. Measurements have been made on crop root growth on two soil types, and the data used to improve the simulation of root growth within the FASSET model. The paper presents the results from root measurements on winter wheat, spring barley and sugar beets, and the root modelling approach we have developed. |
| Tipo: Journal paper |
Palavras-chave: Soil biology. |
| Ano: 2004 |
URL: http://orgprints.org/3879/1/3879.rtf |
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| Jensen, Lars Stoumann; Pedersen, Anders; Magid, Jakob; Nielsen, Niels Erik. |
| It is a well-known fact that catch crops have a significant effect on availability and loss of soil inorganic nitrogen (Thorup-Kristensen et al., 2003) and recently marked effects on soil inorganic sulphur dynamics have also been shown (Eriksen and Thorup-Kristensen 2002; Eriksen et al., 2004). However, we know much less about the effect of catch crops on phosphorous (P) and potassium (K) mobilisation and availability for the next crop. After several years of organic cash crop production, e.g. vegetables and cereals, yield levels may gradually be limited by soil P and K availability, depending on the initial status at conversion to organic production principles. This is particularly the case during the establishment phase of certain vegetable cultures... |
| Tipo: Journal paper |
Palavras-chave: Nutrient turnover Farm nutrient management Recycling; Balancing and resource management Air and water emissions. |
| Ano: 2005 |
URL: http://orgprints.org/6165/1/6165.pdf |
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| Pedersen, Anders; Thorup-Kristensen, Kristian; Jensen, Lars Stoumann. |
| A model analysis of catch crop effects on nitrate leaching was carried out covering three soil types and three precipitation regimes in temperate climate. Catch crops with varying root properties (barssica and rye grass) were used to analyse the effect on nitrate retention in different soil layers. Climate data was taken from 3 different precipitation regimes over 43 years with an average annual amount of rainfall of 709, 796 and 1026 mm. The three soil types were typical Danish sandy soil, a loamy sand soil and a sandy loam. These soil types cover 65 % of the Danish arable area. Simulations covered a winter season from harvest to 1 May the following year. To illustrate the effect of rooting depth of the succeeding crop soil mineral N content is calculated... |
| Tipo: Journal paper |
Palavras-chave: Farm nutrient management; Denmark. |
| Ano: 2009 |
URL: http://orgprints.org/9341/2/9341.pdf |
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| Pedersen, Anders; Thorup-Kristensen, Kristian; Jensen, Lars Stoumann. |
| This model analysis of catch crop effects on nitrate retention covered three soil texture classes sand, loamy sand, sandy loam) and three precipitation regimes in a temperate climate representative for northern Europe (annual precipitation 709-1026 mm) for a period of 43 years. Simulations were made with two catch crops (ryegrass and Brassica) with different rooting depths, and soil N effects in the next spring were analysed to 0.25, 0.75 and 2.0 m depth to represent the catch crop effect on following crops with different rooting depths. Nitrate retained without a catch crop was generally located in deeper soil layers. In the low precipitation regime the overall fraction of nitrate retained in the 0-2.0 m soil profile was 0.23 for the sandy soil, 0.69 for... |
| Tipo: Journal paper |
Palavras-chave: Soil; Farm nutrient management; Air and water emissions. |
| Ano: 2009 |
URL: http://orgprints.org/16122/1/16122.pdf |
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| Pedersen, Anders; Stoumann Jensen, Lars; Thorup-Kristensen, Kristian. |
| The use of crops and catch crops with deep rooting can strongly improve the possibility of retaining nitrate-N that will otherwise be leached to the deeper soil layers and end up in the surrounding environment. But will it always be an advantage for the farmer to grow a catch crop? This will depend on factors such as soil mineral nitrogen level, soil water holding capacity, winter precipitation, rooting depth and N demand of the scceeding crop. These factors interact, and it can be very difficult for farmers or advisors to use this information to decide whether growing a catch crop will be beneficial. To analyse the effect of catch crops under different Danish soil and precipitation conditions, we used the soil, plant and atmosphere model Daisy. |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Nutrient turnover; Post harvest management and techniques; Crop combinations and interactions; Farm nutrient management; Soil quality. |
| Ano: 2005 |
URL: http://orgprints.org/7831/1/7831.pdf |
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| Pedersen, Anders; Thorup-Kristensen, Kristian. |
| Plant soil and atmosphere models are commonly used to predict crop yield and environmental consequence. Such models often include complex modelling modules for water movement, soil organic matter turnover and, above ground plant growth. However, the root modelling in these models are often very simple, partly due to a limited access to experimental data. We present a two-dimensional model for root growth and proliferation. The model focuses on annual crops, and attempt to model root growth of the crops and its significance for N uptake from different parts of the soil volume. |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Production systems; Vegetables; Root crops. |
| Ano: 2004 |
URL: http://orgprints.org/4634/1/4634.pdf |
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| Registros recuperados: 17 | |
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