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Registros recuperados: 25
Primeira ... 12 ... Última
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Clay dispersibility and soil friability – testing the soil clay-to-carbon saturation concept Organic Eprints
Schjønning, P.; de Jonge, L.W.; Munkholm, L.J.; Moldrup, P.; Christensen, B.T.; Olesen, J.E..
Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC as a predictor of clay dispersibility and soil friability. Soil was sampled three years in a field varying in clay content (~100 to ~220 g kg-1 soil) and grown with different crop rotations. Clay dispersibility was measured after end-over-end shaking of field-moist soil and 1-2 mm sized aggregates either air-dried or rewetted to -100 hPa matric potential. Tensile strength of 1-2, 2-4, 4-8 and 8-16 mm air-dried aggregates was calculated from their compressive...
Tipo: Journal paper Palavras-chave: Soil quality.
Ano: 2011 URL: http://orgprints.org/18939/4/18939.pdf
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Compacted subsoils in organic farming: Mechanical loosening and the risk of recompaction Organic Eprints
Munkholm, L.J.; Schjønning, P..
Many soils already exhibit harmfully compacted subsoils. For these soils, improvement of the present poor subsoil structure is needed. Our study showed that biological amelioration comprises a favourable alternative to mechanical subsoiling. Root and earthworm channels constitute effective pathways through compacted layers and significantly improve soil functions like aeration, infiltration and deep rooting. Already, organic farming promote earthworm activity due to the use of diverse crop rotations, catch crops and organic amendments. However, also in organic farmed systems, substantial changes in soil management may be needed to significantly enhance the number of channels in the subsoil. The changes in soil management may include simultaneous changes in...
Tipo: Newspaper or magazine article Palavras-chave: Soil quality Production systems Soil tillage Soil biology Pasture and forage crops Cereals; Pulses and oilseeds.
Ano: 2003 URL: http://orgprints.org/3365/1/DARCOF_Enews_sept03.doc
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Den danske dyrkningsjords tilstand og kvalitet - konsekvenser af trafik og jordbearbejdning Organic Eprints
Schjønning, P.; Munkholm, L.J.; Elmholt, S.; Debosz, K.; Mikkelsen, G.H.; Trautner, A..
Et alsidigt sædskifte og/eller tilførsel af organisk stof til jorden giver en god jordkvalitet (her defineret som en gunstig jordstruktur). Ensidige driftsformer kan i sig selv give anledning til en dårlig jordkvalitet. Jordpakning via trafik på jorden kan eliminere de gode effekter af et godt sædskifte og tilførsel af organisk stof. Trafik på jorden og i endnu højere grad intensiv jordbearbejdning øger risikoen for, at jordens lermineraler dispergeres til vandfasen. Dette kan give tilslemning og skorpedannelse på jorden og indebærer endvidere en risiko for nedvaskning af de vigtige lermineraler fra dyrkningslaget. Der bør foretages undersøgelser af omfanget af denne proces med de i dag anvendte bearbejdningsteknikker. Komprimering af jorden under...
Tipo: Conference paper, poster, etc. Palavras-chave: Production systems Crop health; Quality; Protection Farming Systems Soil quality Soil tillage Crop husbandry Soil biology Cereals; Pulses and oilseeds.
Ano: 2000 URL: http://orgprints.org/1882/1/Konsekvenser_af_trafik.pdf
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En bekvem jord: hvad betyder det og hvordan opnås det Organic Eprints
Schjønning, P.; Munkholm, L.J.; Elmholt, S..
Ensidige sædskifter uden brug af husdyrgødning har vist sig at udpine jorden så meget, at der (bl.a.) bliver problemer med jordens evne til at smuldre under bearbejdning. Økologiske sædskifter vil oftest være så alsidige, at man dér vil opretholde en passende pulje af nydannet, ’aktivt’ organisk stof. Tildeling af husdyrgødning trækker i samme retning. Mekanisk påvirkning af jorden kan eliminere eller i hvert fald reducere de gode effekter af sædskiftet. Der er derfor al mulig grund til at begrænse skadelig pakning af overjorden mest muligt (brug brede lavtryksdæk) samt – om muligt – at undgå brugen af fræser og rotorharver.
Tipo: Conference paper, poster, etc. Palavras-chave: Crop combinations and interactions; Soil quality; Soil tillage; Composting and manuring.
Ano: 2004 URL: http://orgprints.org/5958/1/5958.doc
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Er der krummer i din jord – eller er det bare knolde Organic Eprints
Elmholt, S.; Schjønning, P.; Munkholm, L.J..
Jordens krummer er vigtige for vækst. Både vækst af afgrøden og de svampe og bakterier, der laver bindemidler til nye krummer. Vi har undersøgt, hvordan praktisk økologisk og konventionel drift påvirker dette samspil. Et varieret sædskifte med meget græs og husdyrgødning gav gode stabile krummer med højt indhold af biologiske bindemidler. Et ensidigt kornsædskifte med kunstgødning gav i stedet stabile knolde, hvor bindemidlet var ler. Sådan nogle knolde kan give et dårligt såbed, fordi våd jord bliver blød som mudder og tør jord hård som beton.
Tipo: Journal paper Palavras-chave: Crop combinations and interactions; Soil biology; Soil tillage; Composting and manuring.
Ano: 2005 URL: http://orgprints.org/7425/1/7425.PDF
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Forsknings- og udviklingsaktiviteter på området reduceret jordbearbejdning Organic Eprints
Schjønning, P.; Jørgensen, M.H.; Olesen, J.E.; Rasmussen, G.; Munkholm, L.J.; Melander, B..
Der er fra det danske landbrugserhverv formuleret ønske om, at der iværksættes en bedre rådgivning omkring gennemførelse af reduceret jordbearbejdning, herunder direkte såning (FRDK, bl.a. ved mødet i Forskningskontoret 18. januar 2001). Problemstillingen har interesse for såvel konventionelle som økologiske jordbrugere, idet reduceret bearbejdning af jorden som udgangspunkt er positivt for jordkvaliteten. Der er gennemført en lang række undersøgelser omkring reduceret jordbearbejdning og direkte såning i Danmark. En række forhold har dog til dels gjort disse resultater forældede. Det skyldes bl.a. den politisk bestemte udvikling i de dyrkede afgrøder, herunder i særlig grad sædskiftet, som har stor betydning for reduceret jordbearbejdning. De gennemførte...
Tipo: Report Palavras-chave: Production systems; Soil tillage; Farming Systems; Soil.
Ano: 2001 URL: http://orgprints.org/730/1/redj_not.doc
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Genpakning af jord efter dybdeløsning Organic Eprints
Munkholm, L.J..
Mange års pløjning med traktorhjulet i furebunden samt færdsel med tunge maskiner har betydet, at skadelig pakning af underjorden er et udbredt og tiltagende problem i Danmark. Undersøgelser ved Danmarks JordbrugsForskning viser, at stort set alle danske jorde har et fortættet jordlag under pløjedybden - en såkaldt pløjesål. Mange steder er jorden også pakket længere ned som følge af kørsel med tunge maskiner. Alt andet lige er skadelig pakning et alvorligt problem under økologiske dyrkningsforhold, hvor det vigtigt at bibeholde og fremme en velfungerende og sund jord. Der findes en bred vifte af redskaber, der forholdsvis effektivt løsner en pakket underjord, hvis løsningen vel at mærke foretages under tørre forhold. Alligevel viser de fleste forsøg, at...
Tipo: Newspaper or magazine article Palavras-chave: Soil quality; Soil tillage.
Ano: 2003 URL: http://orgprints.org/1562/1/ljmklumme1.doc
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Jordens smuldreevne har stor betydning Organic Eprints
Munkholm, L.J..
I et Ph.d. projekt undersøgtes effekter af dyrkning vandindhold og dyrkningssystem på jordens struktur i relation til jordbearbejdning. Ideelt set ønskes en let-smuldrende jord, hvor det er let at nedbryde de store uønskede knolde, men samtidig svært at pulverisere jorden. Et knoldet såbed kan give problem med for dårlig rod-jord kontakt, mens et for fint såbed kan give problemer med tilslemning af overfladen og vind- og vanderosion. Jordens smuldreevne har særlig stor betydning indenfor økologisk jordbrug, hvor en optimal planteetablering og gode betingelser for plantevækst er af fundamental betydning for afgrødens evne til at udnytte plantenæringsstoffer og vand, samt for afgrødens konkurrenceevne overfor ukrudt. Jordens smuldreevne afhænger af et...
Tipo: Newspaper or magazine article Palavras-chave: Soil quality Soil tillage Crop health; Quality; Protection.
Ano: 2001 URL: http://orgprints.org/1561/1/ljmklumme2.doc
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Jordkvalitet og dyrkningsmetoder Organic Eprints
Schjønning, P.; Munkholm, L.J.; Elmholt, S..
Ligesom der findes vandkvalitet, luftkvalitet og fødevarekvalitet, findes der jordkvalitet. Og jordens kvalitet hænger nøje sammen med dens struktur, f.eks. dens indhold af partikler og porer. Dette kapitel handler om, hvordan økologisk og konventionelt landbrug påvirker jordkvaliteten. På nogle områder er økologisk landbrug bedst, men ikke på alle.
Tipo: Book chapter Palavras-chave: Soil quality Production systems Crop health; Quality; Protection Soil tillage Farming Systems Crop husbandry Soil biology Pasture and forage crops Soil Cereals; Pulses and oilseeds.
Ano: 2003 URL: http://orgprints.org/1585/1/korrektur2_kap1.pdf
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Management-induced Soil Structure Degradation: Organic Matter Depletion and Tillage Organic Eprints
Kay, B.D.; Munkholm, L.J..
Soil structure is an important element of soil quality since changes in structural characteristics can cause changes in the ability of soil to fulfil different functions and services. Emphasis in this chapter is placed on the role of soil structure in biological productivity of agroecosystems. Combinations of management practices in which the extent of the degradation of soil structure caused by one practice is balanced or exceeded by the extent of regeneration by other practices will help sustain the productivity of agroecosystems. Tillage and practices that change the organic matter (OM) content of soil are foremost among the many practices that influence soil structure. The links between management, OM content and soil structure and between tillage and...
Tipo: Book chapter Palavras-chave: Production systems Crop combinations and interactions Crop health; Quality; Protection Farming Systems Soil quality Soil tillage Crop husbandry Soil biology.
Ano: 2004 URL: http://orgprints.org/1474/1/Chapt11_tex_ref_fig_final.doc
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Mechanical subsoiling: Mitigation of recompaction by light traffic and on-land ploughing Organic Eprints
Munkholm, L.J.; Schjønning, P..
Plough pans have been shown to severely hamper root development, limit rooting depth and reduce crop yield. However, mechanically loosening of compacted subsoils often gives discouraging results. This has in many cases been related to a quick recompaction of the subsoil after loosening, as loosened subsoils are highly prone to recompaction. We evaluated the degree of recompaction of a mechanically loosened sandy loam. In addition, we studied the effect of plough pan compaction and subsoiling on root and yield response for a winter wheat crop. Plots were mechanically loosened to a depth of 35 cm in 1997 and again in 1998. Perennial grass/clover was grown with limited traffic intensity in 1999-2000. The perennial grass/clover was ploughed under in spring...
Tipo: Conference paper, poster, etc. Palavras-chave: Soil quality Production systems Crop combinations and interactions Crop health; Quality; Protection Soil tillage Crop husbandry Soil biology Pasture and forage crops Cereals; Pulses and oilseeds.
Ano: 2003 URL: http://orgprints.org/1480/1/ISTRO2003_pap.doc
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Mitigation of subsoil recompaction by light traffic and on-land ploughing. I. Soil response Organic Eprints
Munkholm, L.J.; Schjønning, P.; Rüegg, K..
Mechanically loosened subsoil has been shown to be prone to recompaction. We evaluated the degree of recompaction of a sandy loam mechanically loosened to a depth of 35 cm in 1997 and again in 1998. Perennial grass/clover was grown with limited traffic intensity in 1999 and 2000. The recompaction experiment was conducted in 2001 and 2002 when the soil was grown with oat and winter wheat, respectively. On-land ploughing was compared with traditional mouldboard ploughing with the tractor wheels in the furrow. In addition, the loosened plots were either light trafficked (<6 Mg axle load and <100 kPa inflation pressure) or heavy trafficked (10-18 Mg axle load and ~200 kPa inflation pressure), respectively. The soils loosened by non-inversion deep tillage...
Tipo: Journal paper Palavras-chave: Pasture and forage crops Cereals; Pulses and oilseeds Soil biology Soil quality Crop husbandry Crop health; Quality; Protection Crop combinations and interactions Production systems Soil tillage.
Ano: 2005 URL: http://orgprints.org/1477/1/recomp_1_subm.doc
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Mitigation of subsoil recompaction by light traffic and on-land ploughing. II: Root and yield response Organic Eprints
Munkholm, L.J.; Schjønning, P.; Jørgensen, M.H.; Thorup-Kristensen, K..
Plough pans have been shown to severely hamper root development, limit rooting depth and reduce crop yields. We evaluated the effect of plough pan compaction on root and yield response for a winter wheat in a field trial conducted in two neighbouring fields (B3 and B4) on a sandy loam. Plots were mechanically loosened to a depth of 35 cm in 1997 (B3 and B4) and again in 1998 (only B4). Perennial grass/clover was grown with limited traffic intensity in 1998-1999 and 1999-2000 for B3 and B4, respectively. The perennial grass/clover was ploughed under in spring 2000 (B3) and spring 2001 (B4) and oats established. After harvest of oats, winter wheat was established. Recompaction treatments were applied to the mechanically loosened plots in 2000 and 2000+2001...
Tipo: Journal paper Palavras-chave: Crop health; Quality; Protection Pasture and forage crops Cereals; Pulses and oilseeds Production systems Soil biology Soil quality Crop husbandry Soil tillage.
Ano: 2005 URL: http://orgprints.org/1479/1/recomp_2_subm.doc
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Modelling soil pore characteristics from measurements of air exchange: the long-term effects of fertilization and crop rotation Organic Eprints
Schjønning, P.; Munkholm, L.J.; Moldrup, P.; Jakobsen, O.H..
Long-term cultivation of soils for arable crops and without application of organic manure is thought to reduce the soil quality for crop production. We studied the porosity of two sandy loam soils from organic dairy farms with a ley cropping system and compared them with a conventionally managed dairy farm growing arable crops only and an arable soil receiving only mineral fertilizers, respectively. Saturated hydraulic conductivity, water retention characteristics, air diffusivity and air permeability were determined in the plough layer of the soil. The soil of one of the organic dairy farms contained many more earthworm burrows and had a significantly larger hydraulic conductivity than the counterpart soil of the conventionally managed dairy farm. In...
Tipo: Journal paper Palavras-chave: Soil quality; Soil biology.
Ano: 2002 URL: http://orgprints.org/44/1/manus2.pdf
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Non-inverting soil tillage as a means of optimising soil tilth Organic Eprints
Munkholm, L.J.; Schjønning, P.; Rasmussen, K.J..
A field experiment was initiated in 1997 with non-inverting soil tillage compared to conventional tillage with annual mouldboard ploughing to either 20 cm depth (CT) or 10 cm depth (RCT). The new system included a non-inverting mechanical loosening of the soil to approximately 35 cm depth combined with a shallow cultivation of the top 5 cm soil by either a rotovator (NIT) or an S-tine harrow (RNIT). The experiment was located on a sandy loam at the organic farmed Rugballegård Experimental Station. A plough pan at 20-35 cm depth was identified by cone penetration measurements. The non-inverting tillage system succeeded in breaking up the plough pan, which reduced the cone index from approximately 1.8 MPa in the CT and RCT treatments to 0.6 MPa in the NIT...
Tipo: Conference paper, poster, etc. Palavras-chave: Soil quality Production systems Soil tillage Crop health; Quality; Protection Crop husbandry Soil biology Pasture and forage crops Cereals; Pulses and oilseeds.
Ano: 1998 URL: http://orgprints.org/1886/1/Non%2Dinverting_soil_tillage.pdf
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Organic matter and soil tilth in arable farming: Management makes a difference within 5-6 years Organic Eprints
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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Organisk stof i jord - hvor meget er nok og hvor lidt er kritisk? Organic Eprints
Schjønning, P.; Munkholm, L.J..
Landbrugsmæssig udnyttelse af jorden medfører et fald i indholdet af organisk stof i forhold til den oprindelige naturlige tilstand, fx med skov. For en dyrket jord har sædskiftet stor betydning, da der eksempelvis indstiller sig et højere indhold af organisk stof i en jord med græs i sædskiftet end i en jord, der alene dyrkes med enårige afgrøder. Der findes således ikke et niveau for organisk stof, der er mere rigtigt end et andet. Det er til gengæld vigtigt at vide, om der findes grænseværdier. Hvor meget er nok, og hvor lidt er kritisk?
Tipo: Web product Palavras-chave: Nutrient turnover Soil quality Root crops Production systems Soil tillage Soil biology Pasture and forage crops Cereals; Pulses and oilseeds.
Ano: 2004 URL: http://orgprints.org/3362/1/FOEJO_Enyt_april_3.doc
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Pløjefri dyrkning: effekter på jordens frugtbarhed Organic Eprints
Munkholm, L.J.; Schjønning, P.; Heckrath, G.; Jørgensen, M.H..
Interessen for pløjefri dyrkning er steget voldsomt gennem de seneste år. Fokus har primært været på de kortsigtede økonomiske gevinster som følge af mindsket tidsforbrug og lavere maskinomkostninger og i langt mindre grad på de langsigtede gavnlige effekter af pløjefri dyrkning på jordens frugtbarhed. Forskellen er slående i forhold til Nordamerika, hvor den udbredte brug af pløjefri dyrkning i høj grad er båret af et ønske om en langsigtet sikring af jordens frugtbarhed (jfr. betegnelsen ”conservation tillage” anvendt for pløjefri jordbearbejdning. I Nordamerika har man især været optaget af pløjefri dyrkning, som et middel til bekæmpelse af vind- og vanderosion. Pløjefri dyrkning er også et anvendeligt redskab til at begrænse pakningen i dybden og den...
Tipo: Conference paper, poster, etc. Palavras-chave: Crop health; Quality; Protection Soil quality Landscape and recreation Soil tillage Soil biology.
Ano: 2000 URL: http://orgprints.org/1885/1/Ploejefri_dyrkning.pdf
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Pore characteristics and hydraulic properties of a sandy loam supplied for a century with either animal manure or mineral fertilizers Organic Eprints
Schjønning, P.; Iversen, B.V.; Munkholm, L.J.; Labouriau, R.; Jacobsen, O.H..
Application of organic residues to soil is generally assumed to improve soil tilth. Only few studies have reported on the long-term effects on the more subtle aspects of soil porosity and no reports have considered the potential effects of organic amendments on the pore system in the subsoil. We sampled undisturbed soil cores (100 cm3 and 6280 cm3) in metal cylinders in differently fertilized plots in the long-term field experiments at Askov Experimental Station, Denmark. We selected the 0-60 cm soil layer of plots dressed for a century with either mineral fertilizers (labelled NPK) or animal manure (labelled AM). Both fertilization treatments were studied at two levels of nutrient application: 'normal' (labelled '1') and 1.5 times 'normal' (labelled...
Tipo: Journal paper Palavras-chave: Nutrient turnover; Crop combinations and interactions; Soil biology; Soil quality; Air and water emissions; Soil tillage; Composting and manuring.
Ano: 2005 URL: http://orgprints.org/5486/1/5486.pdf
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Soil aggregation – a matter of proper management Organic Eprints
Elmholt, S.; Schjønning, P.; Munkholm, L.J..
Soil crumbs are important to soil functions. These include plant growth, and the growth of fungi and bacteria forming agents for binding and bonding of new crumbs. We have studied how commercial organic and conventional farming affect this interaction. A diverse crop rotation, including grass, and animal manure resulted in stable crumbs with a high content of biological binding and bonding agents. A cash crop rotation with the addition of only synthetic fertilizers resulted in small, stable aggregates – more like clods - with clay as binding agent. Such a soil will provide poor conditions for preparing seedbeds, because prolonged rain makes it soft and muddy while drought makes it hard as brick.
Tipo: Journal paper Palavras-chave: Crop combinations and interactions; Soil biology; Soil tillage; Composting and manuring.
Ano: 2005 URL: http://orgprints.org/7423/1/7423.PDF
Registros recuperados: 25
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