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| Registros recuperados: 36 | |
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| Oelofse, Myles; Høgh-Jensen, Henning; de Abreu, L.S.; de Almeira, G.F.; Hui, Q.Y.; de Neergaard, Andreas. |
| Increased demand for certified organic products has led to an increase in the number of certified organic farms in developing countries. Knowledge of farmer nutrient management practices on certified organic farms in developing countries is limited. Thus, the aim of this study was to investigate the impact of the adoption of certified organic agriculture on farm nutrient flows and nutrient budgets, and evaluate to which degree organic farms comply with organic principles relating to nutrient management. The study is based on five case studies of different types of certified organic farming systems in Brazil, Egypt and China. Farm nutrient flows and nutrient budgets for nitrogen, phosphorous and potassium were created for each farm. Four of the five... |
| Tipo: Journal paper |
Palavras-chave: Farm nutrient management. |
| Ano: 2010 |
URL: http://orgprints.org/18298/1/18298.pdf |
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| Adu-Gyamfi, J. J.; Myaka, F.A.; Sakala, W.D.; Odgaard, R.; Vesterager, J. M.; Høgh-Jensen, Henning. |
| Maize (Zea mays L.) is a major staple food in Sub-Saharan Africa but low soil fertility, limited resources and droughts keep yields low. Cultivation of maize intercropped with pigeonpea (Cajanus cajan L. Millsp.) is common in some areas of eastern and southern Africa. The objectives of this study were (1) to investigate dry matter, nitrogen (N) and phosphorus (P) accumulation in different plant components of maize-pigeonpea intercropping systems and (2) to report the effects of the intercrops on soil fertility. Maize-pigeonpea intercrops were compared to sole maize grown using farmers’ practices. Intercropping maize and pigeonpea increased (P<0.05) total system yield compared to sole maize in terms of biomass, N and P accumulation. Pigeonpea planted in... |
| Tipo: Journal paper |
Palavras-chave: Farming Systems. |
| Ano: 2007 |
URL: http://orgprints.org/18306/1/18306.pdf |
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| Foereid, Bente; Høgh-Jensen, Henning. |
| Decline in carbon content in agricultural soils contributes both to climate change and to soil fertility problems. The CENTURY element dynamics simulation model was tested and adapted for Northern European agricultural conditions using long-term datasets from Askov experimental farm in southern Denmark. The part of the model dealing with decomposition was tested in isolation using a bare fallow experiment and it could predict soil organic matter levels with high accuracy. In the cropping experiments predictions were less accurate. The crop production was not accurately predicted. Predictions were more accurate on loamy than on sandy soils. The model was used to predict the effect of conversion to organic agriculture on carbon sequestration as soil organic... |
| Tipo: Journal paper |
Palavras-chave: Environmental aspects. |
| Ano: 2004 |
URL: http://orgprints.org/18304/1/18304.pdf |
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| Oelofse, Myles; Høgh-Jensen, Henning; Abreu, L.S.; Almeida, Gustavo Fonseca de; Hui, Qiao Yu; Sultan, Tursinbek; de Neergaard, Andreas. |
| Based on three case studies in China and Brazil, this paper explores the terms of access for farmers' participation in certified organic agriculture (OA) and investigates the influence of adoption on productivity, nutrient budgets, income and labour use. Small-scale farmers converting to OA require substantial external production-related, marketing and certification support. Access to OA was strongly dependent upon the type of support available to farmers. Organization based on a contract-farming model resulted in OA only being an option available to a narrow group of farmers, whilst OA initiated by a farmer cooperative provided better access. Gross output was significantly higher for oranges, whilst for the other crops gross output was similar. However,... |
| Tipo: Journal paper |
Palavras-chave: "Organics" in general; Quality and evaluation of inputs. |
| Ano: 2010 |
URL: http://orgprints.org/18301/1/Oelofse_et_al_Ecological_Economics_2010_In_press.pdf |
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| Gylfadóttir, Thórey; Helgadóttir, Áslaug; Høgh-Jensen, Henning. |
| The interspecific transfer of nitrogen (N) between white clover (Trifolium repens) and smooth meadow grass (Poa pratensis) in legume-based grasslands was assessed under North European field conditions using 15N individual plant leaf labelling. On average 50% of N in the grass was transferred from the white clover and about 6% of N in white clover was transferred from the grass. This corresponds to 2.5 and 0.3 g N m-2 being transferred over the growing season between the two species respectively and demonstrates that a significant part of the total N of the grass is coming through interspecific transfer. The majority of the 15N transferred was within a period of 20 days at relatively low soil temperatures. This implies that there is a need for a new focus... |
| Tipo: Journal paper |
Palavras-chave: Landscape and recreation; Farm nutrient management; Biodiversity and ecosystem services. |
| Ano: 2007 |
URL: http://orgprints.org/11466/1/11466.pdf |
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| El-Naggar, Ahmed; El-Araby, Ahmed; de Neergaard, Andreas; Høgh-Jensen, Henning. |
| A major challenge for low¬-external-input farming systems is to secure the N supply. Lack of synchrony between mineralization of organic N sources and plant N requirements is causing many growers to use different techniques to overcome this problem. One of these techniques is the application of soluble water extracts of different farm residues and plants. A field study was conducted to study the crop uptake of applied 15N-labeled alfalfa and clover extracts as compared to the N uptake from15N-glycine and three levels of 15N-(NH4)2SO4. The results show that total N accumulation in the field crops, squash and lettuce, was primarily affected by the amount of added N (P<0.05) and not by the form in which the N was applied (P>0.05). The utilization... |
| Tipo: Journal paper |
Palavras-chave: Crop husbandry. |
| Ano: 2008 |
URL: http://orgprints.org/18305/1/18305.pdf |
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| Rasmussen, Jim; Høgh-Jensen, Henning. |
| The C and N dynamics in perennial grass-clover mixtures are not fully understood although such mixtures dominate temperate grassland. The co-existence of clover and grass involves both competition for and transfer of nutrients between the species. The nutrients that are competed for and transferred may originate from leaky root systems, from a rapid turnover of the fine root systems, or from degradation of more stabile organic material. The aim of the present study was to investigate the origin of dissolved organic C and N in perennial grass-clover mixtures. In an existing grass-clover ley, field mezotrons (cylinders with a diameter 30 cm) were installed in the spring of 2003 to depths of 20, 40 and 60 cm. Suction cups was installed beneath the... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Air and water emissions. |
| Ano: 2005 |
URL: http://orgprints.org/9128/1/9128.pdf |
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| Pirhofer-Walzl, K.; Eriksen, Jørgen; Rasmussen , Jim; Soegaard, Karen; Høgh-Jensen, Henning; Rasmussen, Jesper. |
| Aim is to ncrease of plant diversity has been suggested to enhance grassland productivity and resource use efficiency. Most studies on agricultural grasslands have focused on functional diversity of mixtures comprising legumes and non-legumes, but there is little knowledge of plant nutrient acquisition from deep- and shallow-rooted grassland plant species. To investigate whether deep-rooted (chicory: Cichorium intybus L.; Lucerne: Medicago sativa L.) and shallow-rooted (perennial ryegrass: Lolium perenne L.; white clover: Trifolium repens L.) grassland plant species differ in herbage yield and depth dependent soil N-access, we investigated in the field if 1) a mixture comprising shallow- and deep-rooted grassland plant species has greater herbage yields... |
| Tipo: Journal paper |
Palavras-chave: Crop combinations and interactions. |
| Ano: 2012 |
URL: http://orgprints.org/20647/4/20647.pdf |
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| Pirhofer-Walzl, Karin; Eriksen, Jørgen; Rasmussen , Jim; Høgh-Jensen, Henning; Søegaard, Karin; Rasmussen, Jesper. |
| Positive plant diversity-productivity relationships have been reported for experimental semi-natural grasslands (Cardinale et al. 2006; Hector et al. 1999; Tilman et al. 1996) as well as temporary agricultural grasslands (Frankow-Lindberg et al. 2009; Kirwan et al. 2007; Nyfeler et al. 2009; Picasso et al. 2008). Generally, these relationships are explained, on the one hand, by niche differentiation and facilitation (Hector et al. 2002; Tilman et al. 2002) and, on the other hand, by greater probability of including a highly productive plant species in high diversity plots (Huston 1997). Both explanations accept that diversity is significant because species differ in characteristics, such as root architecture, nutrient acquisition and water use efficiency,... |
| Tipo: Journal paper |
Palavras-chave: Crop husbandry; Biodiversity and ecosystem services; Environmental aspects. |
| Ano: 2013 |
URL: http://orgprints.org/23296/1/PLANT%20AND%20sOIL.pdf |
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| Nielsen, Bea; Thamsborg, Stig Milan; Hansen, Hanne; Ranvig, Hans; Høgh-Jensen, Henning. |
| Two trials were conducted to examine the effect of chicory included in or as additional plots of the ryegrass–white clover pastures on growth, naturally acquired nematode infections and selectivity of chicory by lambs. In Experiment 1, 31 weaned Texel lambs (36±7 kg) grazed either ryegrass–white clover (CTRL) or ryegrass–white clover–hicory pastures (CHIC). In Experiment 2, 30 weaned Shropshire lambs (32±7 kg) grazed either ryegrass–white clover (CTRL) or ryegrass–white clover with access to small additional chicory plots, which corresponded to 3% (CHIC-LO) or 6% of the total grazing area (CHIC-HI). No consistent differences in live weight gain and nematode faecal egg counts were observed in lambs grazing the different pasture types. Sward height on the... |
| Tipo: Journal paper |
Palavras-chave: Feeding and growth. |
| Ano: 2009 |
URL: http://orgprints.org/18302/1/Nielsen_2009_Livestock-Science.pdf |
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| Høgh-Jensen, Henning; Loges, Ralf; Jensen, Erik Steen; Jørgensen, Finn V.; Vinther, Finn P.. |
| Symbiotically fixed nitrogen (N2) is an important input of nitrogen (N) source in many agricultural systems. In spite of this fact, the input of symbiotically fixed N to a particular cropping system is usually not known and exact measurements are costly and laborious. Consequently, there is a demand for an uncomplicated and reliable tool to estimate symbiotic N2 fixation (SNF) in leguminous crops. A simple emperical model is proposed for quantification of SNF in forage legumes under low external input conditions. The model estimates SNF using dry matter yield as input and parameters for (i)N concentration in dry matter and the (ii) proportion of the N in the legume that is derived from the atmosphere. Further, the model includes fixed N not included in the... |
| Tipo: Journal paper |
Palavras-chave: Pasture and forage crops. |
| Ano: 2004 |
URL: http://orgprints.org/3085/1/emperical_model.pdf |
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| Høgh-Jensen, Henning; Loges, Ralf; Jensen, Erik Steen; Jørgensen, Finn V.; Vinther, Finn P.. |
| Symbiotically fixed N2 (SNF) is an important input of nitrogen (N) in many cropping systems. In spite of this fact, the input of fixed N to a particular cropping system is usually not known, and an exact estimation of the amount of N2 fixed requires laborious measurements. Consequently, there is a demand for a simple and reliable tool to estimate N2 fixation in leguminous crops. A model is here proposed for quantification of SNF in leguminous crops in different arable systems. The model estimates SNF using dry matter yield as input and cropping system specific values for the parameters: N concentration in dry matter and the proportion of the N in the legume that is derived from the atmosphere. Further, the model includes fixed N not included in the... |
| Tipo: Journal paper |
Palavras-chave: Production systems. |
| Ano: 2003 |
URL: http://orgprints.org/316/1/Emperical_N2%2Dfixation_eng_v6.doc |
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| Liu, Yuexian; Langer, Vibeke; Høgh-Jensen, Henning; Egelyng, Henrik. |
| The objective of this study was to evaluate the differences in the energy consumption between the production of certified organic pear, green food certified pear, and conventional pear in two areas in China. Data were collected from interviews with farmers during 2007 and 2008. Energy inputs were significantly higher in organic systems compared with conventional and green systems. Fertilizer was the most important contributor to energy consumption in all three farming systems. Three calculation methods for energy value of manure have been found in the literature: substitution method, by-product method, and thermal method. The choise of various calculation methods for estimating the energy value of manure turns out to have great influence on the results in... |
| Tipo: Journal paper |
Palavras-chave: Environmental aspects. |
| Ano: 2010 |
URL: http://orgprints.org/18297/1/18297.pdf |
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| Pirhofer-Walzl , K.; Søegaard, Karen; Høgh-Jensen, Henning; Eriksen, Jørgen; Sanderson, M.A.; Rasmussen , Jim; Rasmussen, Jesper. |
| Provision of an adequate mineral supply in the diets of ruminants fed mainly on grassland herbage can present a challenge if mineral concentrations are suboptimal for animal nutrition. Forage herbs may be included in grassland seed mixtures to improve herbage mineral content, although there is limited information about mineral concentrations in forage herbs. To determine whether herbs have greater macro- and micromineral concentrations than forage legumes and grasses, we conducted a 2-year experiment on a loamy-sand site in Denmark sown with a multi-species mixture comprised of three functional groups (grasses, legumes and herbs). Herb species included chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.), caraway (Carum carvi L.) and salad... |
| Tipo: Journal paper |
Palavras-chave: Crop combinations and interactions. |
| Ano: 2011 |
URL: http://orgprints.org/19333/1/19333.pdf |
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| El-Nagger, Ahmed; Ounmaa, Andres; Muukka, Eija; Zaleckas, Ernestas; Abraityté, Gerda; Jansons, Imants; Rasmussen, Jim; Ahnström, Johan; Pirhofer-Walzl, Karin; Jensen, Katherine O’Doherty; Jørgensen, Kirstine F.; Sarunaite, Lina; Bleidere, Mara; Knudsen, Marie Trydeman; Pugliese, Massimo; Nielsen, Merete Højrup Møller; Mugurerza, Natalia Bellostas; Bakewell-Stone, Petra; Hansen, Preben Klarskov; Al-Kufaishi, Sermed Adil Abed-Ali; Kobayashi, Sofie; Rydberg, Torbjörn; Klubova, Vera; Liorancas, Viktoras; Høgh-Jensen, Henning. |
| During one intensive week in October 2005, the authors were gathered to discuss the impact that globalisation has on the Organic Food Systems and the opportunities that globalisation opens up for developing these systems. The meeting took place as a Ph.D. course under the auspices of the Research School of Organic Farming and Food Systems (SOAR; www.soar.dk). All participants research within Organic Agriculture and Food Production in one way or another. |
| Tipo: Journal paper |
Palavras-chave: Food security; Food quality and human health "Organics" in general Food systems Markets and trade Values; Standards and certification. |
| Ano: 2006 |
URL: http://orgprints.org/9333/1/9333.pdf |
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| Rasmussen, Jim; Eriksen, Jørgen; Jensen, Erik Steen; Esbensen, Kim H.; Høgh-Jensen, Henning. |
| Carbon (C) and nitrogen (N) dynamics in ryegrass-clover mixtures were investigated in field mezotrons installed to depths of 20, 40 and 60 cm and equipped with suction cups to collect percolating pore water. Ryegrass and clover leaves were cross-labelled with 14C- and 15N-enriched urea and the fate of the two tracers was studied for three months during summer. Transfer of 14C occurred mainly from ryegrass to clover, whereas the largest transfer of 15N was in the opposite direction. The average transfer of N from clover was 40% (±3.1, n=9) of N in ryegrass, whereas the fraction of N in clover donated by ryegrass was 5% (±1.2, n=9). The amount of 14C transferred from ryegrass to clover was 1.7% (±0.1, n=9) of the 14C-activity in the total aboveground biomass... |
| Tipo: Journal paper |
Palavras-chave: Nutrient turnover; Air and water emissions. |
| Ano: 2007 |
URL: http://orgprints.org/10390/1/10390.pdf |
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| Høgh-Jensen, Henning; Kamalongo, D.; Myaka, F.A.; Adu-Gyamfi, J.J.. |
| Maize is a major food crop in eastern and southern Africa and is often cultivated with insufficient supplies of nutrients. The current studies are aimed at diagnosing any potential nutrient limitation in maize under farmers’ conditions using the nutrient content in ear leaf tissue at tasseling stage. The majority of the maize crops were considered below the critical nitrogen (N) content in the ear leaves with mean N content of 1.84%. Phosphorus (P), B and Cu content appeared critically low at three of the four sites. Unique fingerprinting by multivariate statistics was possible for each site when using the proportion of nutrients in the leaf tissue. The content of six macro elements (N, P, K, S, Mg, Ca) at the tasseling stage were found to be able to... |
| Tipo: Journal paper |
Palavras-chave: "Organics" in general; Crop husbandry. |
| Ano: 2009 |
URL: http://orgprints.org/18303/1/18303.pdf |
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| Høgh-Jensen, Henning; Oelofse, Myles; Egelyng, Henrik. |
| The need for enhancing food production and availability in underprivileged regions of the world requires the attention of scientists. This paper explores the possibilities for rethinking Agricultural Research for Development (AR4D) in the light of new challenges characterized by a high degree of scientific uncertainty and associated with intense political differences of interest. New challenges that particularly influence food production in underprivileged regions include global climate change, globalisation of food chains, and emerging low-carbon energy systems. We argue that by applying the people-centred Sustainable Livelihoods Approach as a research paradigm in AR4D, researchers may be more successful in producing knowledge that is useful to... |
| Tipo: Journal paper |
Palavras-chave: Community development; "Organics" in general; Research methodology and philosophy. |
| Ano: 2010 |
URL: http://orgprints.org/18300/1/18300.pdf |
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| Registros recuperados: 36 | |
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