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| Registros recuperados: 52 | |
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| Thomsen, I. K.; Schjønning, P.; Christensen, B. T.. |
| In order to investigate the effect of soil moisture and texture on C and N mineralization of applied organic matter, sheep faeces was sandwiched between two halves of intact soil cores and incubated at 20°C. The soils contained 10.8 (L1), 22.4 (L3) and 33.7% (L5) clay, respectively, and were drained to seven different matric potentials in the range –15 to –1500 hPa. Evolution of CO2-C was determined during four weeks of incubation. Contents of NO3-N, 15N and microbial biomass N were determined at the end of the incubation. The net release of CO2-C from the faeces (estimated as the difference between soils with and without faeces) and the total CO2-C evolution from soils with faeces was not related to soil moisture contents. Most CO2-C evolved from faeces... |
| Tipo: Journal paper |
Palavras-chave: Nutrient turnover. |
| Ano: 2003 |
URL: http://orgprints.org/271/1/HarmTaskBf%C3%A6ces_rev1.doc |
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| Munkholm, L.J.; Schjønning, P.; Rasmussen, K.J.; Tanderup, K.. |
| Despite more than 30 years of research and practical experience the interest in shallow tillage and especially direct drilling has remained low in Scandinavia. Excessive compaction of the topsoil layer is one of the major problems encountered when adapting shallow tillage and direct drilling in particular. The purpose of this study was to evaluate temporal and spatial effects of two different direct drilling techniques on bulk density and penetration resistance in the near seed environment. A sandy loam growing small grain cereals was followed during the first 3 years after conversion from conventional tillage to direct drilling to reveal short-term changes in soil structure. A field experiment with four blocks was conducted in 1999–2001 where a... |
| Tipo: Journal paper |
Palavras-chave: Soil quality Production systems Soil tillage Cereals; Pulses and oilseeds. |
| Ano: 2003 |
URL: http://orgprints.org/729/1/dirdrill2003.pdf |
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| Schjønning, P.; Thomsen, I. K.; Moldrup, P.; Christensen, B. T.. |
| Quantification of in situ soil microbial activity is indispensable in order to improve manipulation of nutrient turnover in soil and optimize crop nutrient supply. We sampled 100 cm3 cores of undisturbed arable soil at three locations along a naturally occurring clay gradient (L1: 11% clay; L3: 22% clay; L5: 34 % clay). The cores were drained to seven different matric potentials in the range –15 to –1500 hPa and gas diffusion determined prior to a 4 week incubation at 20oC in the dark. For all soils the net nitrification increased with water content to a maximum (L1: 12.1, L3: 10.3 and L5: 8.2 g NO3-N g-1 soil) and then decreased with further increase in water content. The water content at maximum nitrification was 0.26, 0.37 and 0.42 m3 m-3,... |
| Tipo: Journal paper |
Palavras-chave: Nutrient turnover. |
| Ano: 2003 |
URL: http://orgprints.org/273/1/MS_S02%2D0112_text.doc |
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| Munkholm, L.J.; Schjønning, P.. |
| Sustainable soil management requires that the structural degradation is balanced or exceeded by regeneration. Our objective was to investigate the vulnerability of topsoil structure to stress exerted by intensive tillage or traffic. The study addressed the short-term stability to disturbance as well as the recovery (resilience) within a year. A field experiment was conducted in a randomized block design on a humid sandy loam in 1997-1999. Each year, either compaction from a heavy tractor (PAC) or puddling by intensive rotary cultivation (PUD) produced a severe impact on topsoil structure. The PAC and PUD treatments were carried out on wet soil in early spring. The mechanical treatments were referenced by plots (REF), which were left undisturbed until the... |
| Tipo: Journal paper |
Palavras-chave: Soil quality; Production systems; Soil tillage; Farming Systems; Crop husbandry. |
| Ano: 2004 |
URL: http://orgprints.org/1508/1/Struct_vuln_subm.doc |
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| Schjønning, P.; Rasmussen, K.J.. |
| Direct drilling has often been reported to increase density and strength and to affect pore continuity and tortuosity of the upper soil layers. In this study these aspects were studied for three texturally differing soils 4–6 years after initiation of continuous trials with direct drilling and mouldboard ploughing. The soils studied were a coarse sandy soil (Korntved, 5% clay), a sandy loam (Ballum, 8% clay) and a silty loam (Højer, 19% clay). The crop rotation at Korntved was spring barley and winter rye while at Ballum and Højer it was spring barley and winter wheat. Both crops were grown every year. All fields had been mouldboard ploughed for decades prior to the trial period. The ploughed treatment (PL) was imposed in the autumn and the seedbed... |
| Tipo: Journal paper |
Palavras-chave: Soil quality Production systems Cereals; Pulses and oilseeds. |
| Ano: 2000 |
URL: http://orgprints.org/728/1/dirdrill2000.pdf |
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| Chirinda, N.; Olesen, J.E.; Porter, J.R.; Schjønning, P.. |
| Organic and conventional farming practices differ in the use of several management strategies, including use of catch crops, green manure, and fertilization, which may influence soil properties, greenhouse gas emissions and productivity of agroecosystems. An 11-yr old field experiment on a sandy loam soil in Denmark was used to compare several crop rotations with respect to a range of physical, chemical and biological characteristics related to carbon (C) and nitrogen (N) flows. Four organic rotations and an inorganic fertilizer-based system were selected to evaluate effects of fertilizer type, catch crops, of grass-clover used as green manure, and of animal manure application. Soil was sampled from winter wheat and spring barley plots in Sept 2007, April... |
| Tipo: Journal paper |
Palavras-chave: Soil biology; Nutrient turnover; Air and water emissions. |
| Ano: 2010 |
URL: http://orgprints.org/18511/1/18511.pdf |
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| Petersen, Søren O.; Schjønning, P.; Olesen, Jørgen E.; Christensen, S.; Christensen, B.T.. |
| In organic cropping systems, legumes, cover crops, residue incorporation, and manure application are used to maintain soil fertility, but the contributions of these management practices to soil nitrogen (N) supply remain obscure. We examined potential sources of N for winter wheat (Triticum aestivum L.) in four experimental cropping systems established in 1997 on three soil types. Three of the four systems were under organic management. Topsoil N, depth of the A horizon, and cumulated inputs of N since 1997 were determined at plot level. Labile soil N pools (mineral N, potentially mineralizable N [PMN], microbial biomass N [MBN]) were monitored during two growth periods; at one site, biomass C/N ratios were also determined. Soil for labile N analysis was... |
| Tipo: Journal paper |
Palavras-chave: Crop combinations and interactions; Soil biology; Nutrient turnover; Farm nutrient management. |
| Ano: 2013 |
URL: http://orgprints.org/22015/7/22015.pdf |
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| Schjønning, P.; Elmholt, S.; Christensen, B.T.. |
| The industrialization of agriculture and the concurrent increase in societal concerns on environmental protection and food quality have put focus on agricultural management and its impact on soil quality. Soil quality involves the ability of the soil to maintain an appropriate productivity, while simultaneously reducing the effect on the environment and contributing to human health. This development has changed society’s expectations to science and there is an urgent need to improve the communication among researchers from different scientific disciplines. The interaction of scientists with decision-makers is a topic of utmost relevance for future developments in agriculture. Reflexive objectivity denotes the exercise of raising one’s consciousness of the... |
| Tipo: Book chapter |
Palavras-chave: Research methodology and philosophy; Soil. |
| Ano: 2004 |
URL: http://orgprints.org/1470/1/A4659_Schjonning_Chap01.pdf |
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| Van den Akker, J.J.H.; Schjønning, P.. |
| Subsoil compaction affects all aspects of soil quality, and contrary to topsoil compaction it is persistent. Natural alleviation processes such as wetting/drying, freezing/thawing and biological activity including root growth decrease rapidly with depth. In compacted soil, these alleviation processes are moreover diminished because root growth and biological activity are reduced and soil water contents remain higher in compacted than in well-structured soil. Wheel loads are still increasing and, in consequence, the extent and severity of subsoil compaction. Sustainable soil management requires the uncompromising criterion that no subsoil compaction can be accepted. Consequently, only field traffic with wheel loads lower than the carrying capacity of the... |
| Tipo: Book chapter |
Palavras-chave: Buildings and machinery; Soil quality; Soil tillage; Soil biology. |
| Ano: 2004 |
URL: http://orgprints.org/1473/1/Chapt10_tex_ref_tab_final.doc |
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| Elmholt, S.; Schjønning, P.; Munkholm, L.J.; Debosz, K.. |
| In order to improve our understanding of soil aggregation, we have studied the relative importance of bonding and binding mechanisms, especially how they scale according to aggregate size and how they are influenced by farming system and different management options. Topsoil samples were collected from four arable sandy loam soils found as two pairs (FP1 and FP2) of neighbouring fields. One of the fields in FP2 had been grown for decades with annual cash crops without application of organic manures, while the other three fields had been managed with diversified crop rotations and manure dressings. Aggregates were segregated from the bulk soil by promoting brittle failure. The samples of soil structural units were fractionated to 4-8 mm, 0.5-1 mm and... |
| Tipo: Journal paper |
Palavras-chave: Crop combinations and interactions; Soil biology; Soil quality. |
| Ano: 2008 |
URL: http://orgprints.org/14642/1/Geoderma_2008_TwoPairs.pdf |
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| Jacobsen, O.H.; Vinther, F.P.; Schjønning, P.; Hansen, E.M.; Eriksen, J.. |
| I Danmark har det høj prioritet, at vi kan drikke vores grundvand uden rensning. Der er en voksende erkendelse af, at rent grundvand kun kan opretholdes gennem en aktiv indsats. Amterne udpeger områder med særlig drikkevandsinteresser og efterfølgende zonerer de for arealer der er særlig nitrat- og pesticidfølsomme. En perspektivrig mulighed for at regulerede i forureningsfølsomme om-råder kan være, at man udlagde større sammenhængende arealer med økologisk jordbrug. Først og fremmest undgår man helt brug af pesticider. For kvælstof, vil tabet være afhængig af det økologi-ske dyrkningssystem og det er det der er fokus for denne undersøgelse. |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Nutrient turnover; Farm nutrient management; Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/5957/1/5957.doc |
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| Registros recuperados: 52 | |
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