Ievina Sturite

Forsker

(+47) 934 99 484
Ievina.Sturite@nibio.no

Sted
Steinkjer

Besøksadresse
Innocamp Steinkjer, Skolegata 22, Bygg P 1. etasje, 7713 Steinkjer

Sammendrag

More than 2/3rds of Norway’s agricultural area are grassland, and more than half of it is over 5 years old. Renewing old grassland increases annual yield but causes yield loss during renewal. Parts of the increased yield is due to replacement of low-productive species with high production species and cultivars, replacing biodiversity with productivity. Finding the optimal rate of renewal requires long term experiments to compare the sustainability of different strategies. Therefore, three field experiments were established to investigate the effect of difference renewal and harvest strategies on grass yield and quality, on similar mineral soil at Særheim (58.5°N, 5.6°E) in 1968 and Fureneset (61.3°N,5.0°E) in 1974, and on peat soil at Svanhovd (69.5°N,30.0°E) in 1968. Until 1991, the experiment included non-renewed treatments, and renewal every 3rd or 6th year. It was cut either two or three times a year, with autumn grazing on parts of the two-cut regime. The experiment was simplified in 1992, with the establishment of another non-renewed treatment, all treatments being cut 3 times a year (2 at Svanhovd), no grazing but contrasting slurry and compound fertilizer applications. This phase lasted until 2011, followed by period with no renewal and minimal registration. The third phase started in 2016, with renewal of all treatments at Fureneset and Særheim, except the permanent grassland from 1968/1974. Duration between renewals was doubled, and fertilizer applications revised. Presenting results from the third phase, we show that five to six years are required to recoup and significantly over-yield the non-renewed grassland. We will use soil chemical and physical properties, fertilizer application and yield gaps as well as ecological succession from sown seed mixture in 2017 till 2022 grassland to discuss the why we needed six years for all renewed treatments to over-yield permanent grassland from 1974.

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Sammendrag

Despite newly approved lucerne cultivars, this has not led to increased use of this legume in high-latitude agriculture. Challenges with inoculation by Rhizobium meliloti have been identified as a bottleneck to adaptation. Here we tested inoculation sources (ISs) with soil types and cultivars in pot and field experiments. During a one-year outdoor pot experiment, we tested the impact of IS (wet peat slurry and Nitragin Gold dry inoculation) and three soil types (sand, sandy silt and /peat soil) on nodule development, shoot and root growth and winter survival of one hybrid lucerne cultivar (‘Ludvig’). The pot experiment revealed that dry inoculation led to significant better plant growth, flower and nodule development as well as plant regrowth after winter survival. Peat soil appeared as the best growth medium and silty soil limited inoculation efficiencies. In field trials at two locations differing in soil characteristics using similar ISs, and three hybrid lucerne cultivars (‘Lavo’, ‘Live’ and ‘Lotte’) biomass yield during two ley years showed site as well as cultivar differences. Such environmental interactions in the field trials justify the use of adapted cultivars, and dry inoculation should be recommended for practical use replacing peat slurry inoculation.

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Sammendrag

Enhancing carbon storage in managed soils through increased use of cover and catch crops in cereal cropping is at the heart of a carbon-negative agriculture. However, increased C storage by additional biomass production has a nitrogen cost, both in form of increased N fertilizer use and by potentially increasing nitrous oxide (N2O) emissions when cover crops decay. Frost-sensitive, N-rich aboveground biomass may be a particular problem during wintertime, as it may fuel off season N2O emissions during freezing-thawing cycles, which have been shown to dominate the annual N2O budget of many temperate and boreal sites. Here we report growing season and winter N2O emissions in a plot experiment in SE Norway, testing a barley production system with seven different catch and cover crops (perennial and Italian ryegrass, oilseed radish, summer and winter vetch, phacelia and an herb mixture) against a control without cover crops. Cover crops where either undersown in spring or established after harvesting barley. While ryegrass undersown to barley marginally reduced N2O emissions during the growing season, freeze-thaw cycles in winter resulted in significantly larger N2O emissions in treatments with N-rich cover crops (oilseed reddish, vetch) and Italian ryegrass. N2O budgets will be presented relative to aboveground yield and quality of cover crops and compared to potential souil organic carbon gains.

Sammendrag

Det er dyrket korn i Nord-Norge siden sein steinalder og kornet var en viktig del av kostholdet. Etter andre verdenskrig ble kornarealet i nord kraftig redusert. Med klimaendringer og med en økt markedsinteresse, er korndyrking igjen blitt aktuelt i nord. En av de største utfordringene er finne egnede sorter for nordlige strøk, og i dette prosjektet har vi testet de sju gjenværende nordnorske sortene for å teste hvor tilpasset de er dagens klima. Selv om resultatene er usikre, mener vi at Dønnes bygg samt at Nordlys og Bode kan være aktuelle byggsorter i Nordland. I Troms og Finnmark kan dyrking av Nordlys bygg være interessant, samt at Bode og Dønnes kan være aktuelle byggsorter. Pol havre og Vågønes vårrug er de eneste sortene av havre og rug fra Nord-Norge. Disse kan være aktuelle for dyrking i nord. Pol havre kan spesielt være interessant for dyrking til fôr i Troms og Finnmark. Videre utprøving kan gi sikrere resultat.

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Sammendrag

Denne rapporten vurderer bruk av georadar 3D GPR for å kartlegge jordsmonn i landbruksjord. Visualisering av data fra 3D GPR ble sammenlignet med data fra EM38 og med jordanalyser som beskriver jordas sammensetning. Bruk av flere metoder på samme areal tydet på at 3D GPR kan være et viktig verktøy for å avdekke jordvariasjon og eksisterende dreneringssystemer i jorda.

Sammendrag

Several studies conclude that permanent and temporary swards are equally productive, given equal management. In Norway, one experimental field trial has been maintained since 1974 (Fureneset; 61°18’N, 5°4’E). This ongoing experiment includes long-term/permanent ley (no-tillage over 25 and 45 years) next to temporary leys reseeded regularly. The objective of the study was to test reseeding/ renovation methods that may maintain long-term forage productivity. We hypothesized that sod seeding after chemical fallowing improves grassland productivity equally to that from reseeding after ploughing. In 2017, the frequently ploughed treatments, and half of the 25-year-old sward, were renewed by ploughing and reseeding with grass-clover seed mixtures. The second half of the 25-year-old sward was chemically fallowed and sod-seeded. The treatments included three different fertilizer strategies: mineral fertilizer (210 N kg ha-1) and cattle slurry in combination with mineral fertilizer (210 and 340 kg total-N kg ha-1). On average for four production years (2018-2021) the dry matter yield (DMY) of permanent sod-seeded 25-year-old ley was about 11 t ha-1, and these yields were equal to swards renewed by ploughing and reseeding.

Sammendrag

Inclusion of clover in grasslands increases functional diversity, N yield and forage quality and has been advocated for mitigating nitrous oxide (N2O) emissions. However, boreal grass-clover leys often show poor winter survival with considerable aboveground losses of nitrogen (N) and carbon (C). Little is known about how these losses affect off-season N2O emissions. Here we report field experiments over two winters, conducted at two coastal locations in Western and Northern Norway. N2O emissions were measured in plots with 0, 30 and 100% red (T. pretense) and white clover (T. repens) in a timothy - meadow fescue mixture. Overwinter N loss from the sward was quantified by comparing N contents in roots, stubble and herbage in autumn and spring. Additional treatments were removal of above-ground biomass in autumn and soil compaction. Off-season N2O emissions correlated positively with estimated overwinter N loss from herbage, which in turn depended on the fraction of clover in the ley. Pure grass leys emitted less N2O than leys that contained clover. Corrected for background emissions from pure grass, up to 13% of the above-ground N loss was emitted as N2O–N when clover was grown in pure stand. This fraction was much smaller, however, when clover was grown in mixture with grass (1.9 ± 0.9%), suggesting reassimilation of inorganic N. Indeed, we found significant increases in root and stubble N in mixtures throughout winter. Removal of above-ground biomass in autumn appeared to reduce the sward's ability to retain N throughout winter, and hence had no or a stimulating effect on N2O emissions. Soil compaction increased off-season N2O emissions 1.3–1.6-fold. Our results show that boreal grass-clover leys can be a significant source of N2O during winter, intricately controlled by loss and reassimilation of N. This underscores the importance of off-season plant-soil management for reducing the greenhouse gas (GHG) footprint of animal production in high latitude ecosystems.

Sammendrag

Karboninnholdet i jord har gått ned i store deler av verden. Også i Norge. For landbruket er det derfor viktig med driftsmåter som øker lagringen av karbon i jordsmonn. Gras til eng og beite er et effektivt CO2-lager, men jordart og driftsmåte kan påvirke lagringsevnen.

Sammendrag

Perennial versus short term (<3 years) grass vegetation cover is likely to have considerable differences in root density and thus carbon (C) inputs to soil. Carbon inputs are important to maintain soil organic carbon (SOC) and may even increase it. In Norway and Scandinavia, the SOC content in soil is often higher than in other parts of Europe, due to the cold climate and high precipitation (i.e. slower turnover rates for soil organic matter) and a dominance of animal production systems with a large amount of grassland. Here we aimed to evaluate differences in SOC content, down to 60 cm depth, of a long-term grassland (without ploughing for decades) and a short-term grassland (frequently renewed by ploughing) under contrasting climate, soil and management conditions. Quantification of SOC was carried out on three long-term experimental sites on an extended latitude gradient in West and North Norway. The samples were taken from 4 depth increments (0-5, 5-20, 20-40 and 40-60 cm) in treatments that have not been ploughed for at least 43 years, and in treatments that were ploughed every third year until 2011. Preliminary results suggest that there is no significant difference in SOC storage down to 60 cm between long-term and short-term grasslands.

Sammendrag

Denne rapporten er utarbeidet på oppdrag for Landbruksdirektoratet til Klimakur2030. Rapporten omhandler utredning av fangvekster som klimatiltak. Utredningen inkluderer en vurdering av hvilke områder og arealer som er egnet til å dyrke fangvekster og i hvilke områder fangvekster kan ha best effekt. Det er produsert fylkesvis arealstatistikk for potensielle korndyrkingsarealer basert på det detaljert jordsmonnkartlagte arealet av fulldyrka og overflatedyrka jord. Den nye arealstatistikken er brukt for å estimere det totale potensialet for dyrking av fangvekster i korn. Det er også laget arealstatistikk for dyrking av fangvekster etter høsting av tidligkulturer som grønnsaker og poteter i Vestfold. Basert på arealer egnet for dyrking, samt anslått gjennomføringsgrad er det vurdert muligheter for utslippsbesparelser gjennom karbonbinding i jordbruksjord og lystgassutslipp med hovedvekt på perioden 2021-2030. Det er også gjort kostnadsberegninger, både privatøkonomisk og samfunnsøkonomisk for ulike dyrkingsmetoder av fangvekster. Videre er det gjort vurderinger av aktuelle arter av fangvekster som er passende og aktuelle for det norske klimaet. Det er lite kunnskap om hvilke arter som gir best karbonlagring for norske forhold. I rapporten er det gitt oversikter over og avgrenset hva som skiller de ulike begrepene fangvekster, dekkvekster, underkultur og grønngjødsling fra hverandre.

Sammendrag

Tålmodighet er en dyd. Men det kan oppleves risikofylt å vente tålmodig på at ei langvarig eng skal finne balansen som kreves for å oppnå god avling og kvalitet. Likevel er det nettopp det forsker i NIBIO, Ievina Sturite, ber oss vurdere. Resultatet kan vise seg lønnsomt , både for økonomi og miljø.

Sammendrag

Beiting av tamrein på dyrka mark kan forårsake store konflikter mellom landbruksnæring og reindriftsnæring. Som følge av årlige konflikter med rein på vinterbeite på Helgelandskysten, ble det gjennomført et forprosjekt i Dønna kommune. Målet med dette prosjektet var å høste erfaringer med metodebruk og gjøre en foreløpig beregning av eventuell avlingsskade forårsaket av at tamrein beiter på innmark. Avlingstall fra 12 forsøksfelt, posisjoner fra 30 GPS-merkede simler samt dokumentasjon av tamrein- og viltforekomster fra fem viltkameraer, danner datagrunnlaget for resultatene. Forsøket varte gjennom hele vinter- og vårperioden 2019 fram til 1. slått i slutten av juni. Resultatene viste ingen statistisk sikre forskjeller i grasavlinger mellom engarealer som var eksponert for reinbeiting (og annet hjortevilt) og arealer som var skjermet for dette. Dataene var imidlertid preget av stor variasjon og få gjentak. Ytterligere tallmateriale fra et større geografisk område og over flere år vil være nødvendig for å identifisere eventuelle effekter. Resultatene viste også at tamreinen foretrakk myr, kystlynghei og fulldyrka innmark framfor andre vegetasjonstyper. Forsøksfelt-metodikken som ble brukt for å beregne avlingsmengden i beita og ubeita ruter fungerte svært tilfredsstillende. Metoden for beiteskadetaksering, som i utgangspunktet var utviklet for hjort, må imidlertid kalibreres for tamrein dersom den skal benyttes videre.

Sammendrag

Beiting av tamrein på dyrka mark kan forårsake store konflikter mellom landbruksnæring og reindriftsnæring. Som følge av årlige konflikter med rein på vinterbeite på Helgelandskysten, ble det gjennomført et forprosjekt i Dønna kommune. Målet med dette prosjektet var å høste erfaringer med metodebruk og gjøre en foreløpig beregning av eventuell avlingsskade forårsaket av at tamrein beiter på innmark. Avlingstall fra 12 forsøksfelt, posisjoner fra 30 GPS-merkede simler samt dokumentasjon av tamrein- og viltforekomster fra fem viltkameraer, danner datagrunnlaget for resultatene. Forsøket varte gjennom hele vinter- og vårperioden 2019 fram til 1. slått i slutten av juni. Resultatene viste ingen statistisk sikre forskjeller i grasavlinger mellom engarealer som var eksponert for reinbeiting (og annet hjortevilt) og arealer som var skjermet for dette. Dataene var imidlertid preget av stor variasjon og få gjentak. Ytterligere tallmateriale fra et større geografisk område og over flere år vil være nødvendig for å identifisere eventuelle effekter. Resultatene viste også at tamreinen foretrakk myr, kystlynghei og fulldyrka innmark framfor andre vegetasjonstyper. Forsøksfelt-metodikken som ble brukt for å beregne avlingsmengden i beita og ubeita ruter fungerte svært tilfredsstillende. Metoden for beiteskadetaksering, som i utgangspunktet var utviklet for hjort, må imidlertid kalibreres for tamrein dersom den skal benyttes videre.

Sammendrag

Vi lever i et samfunn som har kommet langt i likestilling mellom kjønn. Likevel opplever mange daglig tilfeller av hersketeknikk og forskjellsbehandling, også innen forskermiljø. Men kvinner kan gjøre mye selv for å ta kontroll over disse forskjellene. Gjennom å sikte høyt og gi litt faen, stole på seg selv, sin kompetanse og magefølelsen. Og må du rope litt høyere for å bli hørt? Ja, så rop!

Sammendrag

Fangvekster sås sammen med korn eller etter tidligkulturer for å ta opp overskudd av næringsstoffer og redusere erosjon. Fangvekster øker karboninnholdet i jorda og reduserer ugrasmengden. Fangvekster har lenge vært anerkjent som et vannmiljøtiltak, og studier tyder på at det også er et aktuelt tiltak for å redusere klimagassutslippene fra jordbruket.

Sammendrag

En økning i karbonlagring i landbruksjord er angitt som et viktig klimatiltak både internasjonalt og i Norge. Tiltaket er godt begrunnet: Jorden inneholder to til tre ganger så mye karbon som atmosfæren, noe som innebærer at relative små endringer i innhold av karbon i jord kan ha betydelige effekter på CO2-innholdet i atmosfæren og det globale klimaet. Det er godt dokumentert at intensive jordbruksmetoder har ført til en reduksjon i jordkarbon og derfor ønskes det en reversering av denne trenden (dvs. økt karbonbinding i jord), som tiltak både for klima og matproduksjon. I denne rapporten er det gjort vurderinger av hvordan dette kan gjøres i Norge og hvilken klimaeffekt som kan oppnås...

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Sammendrag

Multilocation testing remains the main tool for understanding varietal responses to the environment. Here, Latvian and Norwegian hull-less and hulled barley varieties were tested in field experiments in Latvia and Norway in order to assess the varieties adaptability across environments (sites). Two Latvian (cv Irbe and cv Kornelija) and one Norwegian hull-less barley variety (cv Pihl) were tested along with one Latvian (cv Rubiola) and one Norwegian hulled barley variety (cv Tyra) under conventional and organic management systems. The grain yield, together with physical and chemical grain parameters were compared, and variety yield and protein stability detemined. Overall, grain yield of hull-less barley varieties was significantly lower than for hulled barley varieties regardless of climatic conditions and management system. However, in the organic farming systems this difference between barley types was less pronounced. The hull-less barley varieties cv Pihl and cv Irbe, along with both hulled varieties, had good yield stability across environments and were well adapted to both cropping systems. Hull-less barley varieties tended to contain more protein and β -glucans than hulled barley varieties. Despite being bred for local conditions in Norway and Latvia, our study shows that all the varieties used may be successfully transferred across countries.

Sammendrag

Slåttemark har status som trua naturtype jfr. naturmangfoldloven. Restaurering og skjøtsel av resterende artsrike slåttemarker er tids- og ressurskrevende siden de er ofte små, bratte eller grunnlendte. Samtidig har det blitt anbefalt å etterligne mest mulig det tradisjonelle bruksregimet som inkluderer ljåslått (eller tohjulstraktor), bakketørking/hesjing og fjerning av graset for å sikre det biologiske mangfoldet. Tilskuddsordningen for trua naturtyper skal stimulere til å restaurere og holde verdifulle slåttemarkene i hevd ved å gi tilskudd til den arbeidskrevende slåtten. For å få flest mulige lokaliteter bevart for framtiden er det viktig at arbeidsmengden og krav om utstyr og håndtering av graset under restaurering og skjøtsel er overkommelig uten at det går på bekostning av artsmangfoldet. Hovedmålsettingen med prosjektet var å undersøke hva slags effekt økt mekanisering av slått har på artsmangfoldet i verdifull slåttemark ved å erstatte bruk av ljå og tohjulstraktor med ryddesag eller beitepusser......

Sammendrag

I vinter har snøen lavet ned rundt om i landet. Og snøen er bra for mer enn skiføret. Den ligger som et teppe over landskapet og beskytter plantene mot kulda. Men hva betyr ulike snøforhold for landbruket?

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Sammendrag

Sammendrag: Denne rapporten gir en oppdatert oversikt over tiltakspotensiale for tiltak som jordbruket kan iverksette for å redusere klimagassutslipp. Det er tiltak innen dagens produksjonsystemer og struktur som er vektlagt. Det er sammenlignet med vurderinger gjort i rapporten «Landbruk og klimaendringer» fra 2016. Effekt av tiltak, gjennomføringsgrad og forutsetninger for gjennomføring til 2030 er prioritert.

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Sammendrag

Aims: Evaluate biological nitrogen fixation (BNF) and its contribution to total N yield in different grass-clover mixtures under a boreal coastal climate and assess how winter conditions affect the survival of clover and its capability to fix nitrogen (N). Methods: Grass-clover mixtures sown with 0, 15 and 30% red and white clover were subjected to two N rates and three levels of tractor trafficking over four years. BNF was estimated by N-difference for each of the two harvests per year, whereas the first harvest was used to estimate the fraction of N derived from the atmosphere (NdfA) and its transfer to grasses by 15N natural abundance. Results: Biological N fixation, mainly by red clover, contributed substantially to total N yield, which was up to 75% greater in grass-clover mixtures than in pure grass stands in the second production year. However, the number of red clover plants and associated BNF decreased dramatically in the third and fourth production year, with N fertilization rate having a more detrimental effect than soil trafficking. Conversely, the amount of biologically fixed N transferred to grass, increased with time, evidencing that some of the biologically fixed N is retained in the system. In the first harvests, NdfA values were generally between 80 and 100%, irrespective of preceding winter conditions. Conclusions: BNF in high latitude grass-clover mixtures can be substantial but is limited by the poor survival of red clover. Variable winter conditions had no measurable effect on winter survival nor on the sward’s capacity to fix nitrogen in spring.

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Sammendrag

The aim of the study was to investigate changes of physical, microbiological, and sensory properties of muesli with germinated fakes during storage. Germinated fakes were made from conventionally grown grains: hullless barley, hull-less oat, rye, wheat, and triticale in various proportions. Breakfast cereals samples were packaged in Doypack (stand up pouches) made from Pap50g/Alu7/ Pe60 (Pap/Alu/PE) and stand up pouches Fibrecote® HB MG 40/60 (PE/EvOH/Pap) and stored for 6 months at temperature t=35±2°C and relative air humidity φ=55±3%, to provide accelerated shelf-life testing. The main quality parameters such as total plate count, yeasts and mould, water activity, moisture content, water absorption and sensory properties—taste, aroma, consistency, and appearance were analysed using the standard methods. The results of the present experiments demonstrate that the best quality of dried breakfast cereals after storage in terms of sensory quality, microbiological stability, moisture migration, and water absorption were achieved in the Fibrecote® HB MG 40/60 pouches. This study revealed that breakfast cereals made from rye, triticale germinated triticale, germinated hull-less oat, germinated hull-less barley fakes; as well breakfast cereals made from triticale, oat, germinated wheat, germinated triticale, and germinated hull-less barley fakes packaged in Fibrecote® HB MG 40/60 can be stored for 12 months at temperature 23±2°C; but breakfast cereals made from wheat, rye, triticale, germinated hull-less oat, germinated hull-less barley, germinated rye fakes and package in same packaging material can be stored for 10 months at temperature 23±2°C.

Sammendrag

Vekta på traktorar og utstyr har auka mykje sidan eldre feltforsøk med jordpakking i eng vart utført i Noreg. Vi har undersøkt korleis køyring med dagens traktorar påverkar jordfysiske forhold, avling, plantesetnad og fôrkvalitet av rein graseng og kløverblanda eng i ein forsøksserie på tre einingar i NIBIO, på Tjøtta i Nordland, på Fureneset i Sunnfjord og på Løken i Valdres. Traktorkøyring gav stor avlingsnedgang (20 %) på siltjord i Valdres, medan nedgangen var meir moderat (6 %) på siltig sandjord på Fureneset og det var ingen avlingseffekt på sandjord med god luftveksling på Tjøtta. Det var små forskjellar mellom bruk av lett eller tung traktor, og resultata viser at ein i størst mogleg grad bør unngå køyring under våte forhold på jord som er utsett for pakkingsskade. Køyring på siltjord førte til endringar i den botaniske samansetnaden i enga ved at raudkløver og tofrøblada ugras gjekk tilbake og kvitkløver og grasugras gjekk fram. Køyring på siltjord reduserte også opptak og fiksering av nitrogen. Bruk av kløver i frøblandinga gav stor positiv effekt på avling, protein- og mineralinnhald og gav lågare fiberinnhald i fôret. Bruk av 6 kg N i mineralgjødsel etter førsteslått gav god avlingseffekt, men reduserte kløverinnhald og biologisk nitrogenfiksering. Sterkare nitrogengjødsling og bruk av kløver endra grasbestanden i enga i retning av meir timotei og mindre engsvingel. Auke i såmengda av kløver frå 15 % til 30 % på vektbasis gav små utslag på avling og botanisk samansetjing, men auka Nfikseringa med 0,5 kg per dekar og år.

Sammendrag

Red clover (Trifolium pratense L.) is normally a short-lived perennial with no vegetative propagation and the number of plants in the field declines rapidly. In organic farming, the amount of clover in the field is decisive for the N2 fixation and yield, the protein content and quality of the forage produced. In Nordland County (66.27°N), there is a farm with some red clover plants in more than 15 years old grassland. In the presented study we examined grassland botanical content and attempted to recognise age of red clover plants. Our hypotheses was 1) that extensive grassland management promotes self-seeding of red clover 2) self-seeding maintaining a desired content of red clover over time. In addition, we tested two harvesting regimes of the first cut for seed maturation and seed quality at two locations in Norway. Red clover plants in old swards showed very high age and a branched root system. Only very few seedlings were found in old sward suggesting that self-seeding was insignificant. Experiments with leaving the grassland after the first cut for seed production of clover failed due to poor seed maturation. Surface seeding of red clover in pure grass plots gave good results, especially with early spring seeding.

Sammendrag

A future wetter climate in Northern Europe may increase soil compaction from traffic of heavy machinery. This study investigated the impact of tractor traffic on grassland yield, soil physical properties and penetration resistance in three experimental field trials in Norway; on medium sand at Tjøtta, Nordland, on silty medium sand at Fureneset, Sogn og Fjordane and on silt at Løken, Oppland. The experiments were conducted in a split-plot design with three levels of two wheel-by-wheel passes with tractor traffic after each cut: no traffic, light tractor or heavy tractor on large plots, and three different seed mixtures on small plots. The yield reduction by tractor traffic was 26% at Løken, 4% at Fureneset and 1% at Tjøtta. There was a positive correlation between soil moisture content and yield reduction by traffic. Tractor traffic reduced pore volume and air capacity and increased bulk density, compaction degree and penetration resistance with the largest effect at Løken and the smallest at Tjøtta. There were no statistically significant differences in yield or soil physical properties between light and heavy tractor. The study shows that soil texture and soil moisture content are major factors explaining traffic effects on soil physical properties and grassland yield.

Sammendrag

In order to detect the efficiency of the nitrogen (N2) fixation in clover-grass leys in northern climate conditions, we studied how soil compaction affects growth and N2 -fixation of white clover (Trifolium repens L.) under contrasting growth conditions. A pot experiment was carried out under controlled climatic conditions in the phytotron at Holt (Tromsø). Sandy soil was compacted to two levels, 60% and 85% of the standard degree of compactness (SDC). Four seedlings of white clover plants or timothy (Phleum pratense L.) were carefully planted in each pot. Timothy was used as reference plant. The plants were placed at 15 ºC for twelve weeks and subjected to 18 or 24 h daylight. The 15N isotope dilution method was used to assess N2 -fixation. Results suggest that 24 h daylight increased white clover biomass production as compared to 18 h daylight and favoured leaf and stolon production significantly more at 85% of SDC than at 60% of SDC. However, for white clover plants grown at 18 h day length higher compactness reduced the root development. On average, white clover derived 44-58% of its total N from N2 -fixation grown at 60% of SDC and 46-47% at 85% of SDC, regardless of light conditions. The N2 -fixation was somewhat higher at 24 h day length only under the low soil compaction level.

Sammendrag

Luserne (Medicago sativa L.) er ein fôrvekst med stort avlingspotensial, og tilpassa sortar greier seg godt i låglandet i Sør-Norge. Luserne krev god jordstruktur og høg pH i jorda for å trivast, og frøet må smittast med rett type bakteriekultur før såing. Nitrogenfikseringa kan bli høg der arten trivst. Fôrverdien er høgast på ungt stadium, og energiverdien går raskt ned med aukande stengelutvikling. Proteinverdien er generelt høg. Norsk foredlingsmateriale er meir hardført enn utanlandsk plantemateriale, og nye foredlingslinjer (LøLu9822, LøLu9823) har gjort det betre i forsøk enn sorten "Live". Linja LøLu9821 ser ut til å vera mest hardfør. I forskingsrådprosjektet "Engbelgvekstar - dyrking - klima" blir ulike lusernelinjer prøvt i utkanten av mulig dyrkingsområde, og dyrkingsteknikk til luserne blir nærmare undersøkt på Bioforsk-stasjonane Apelsvoll, Løken og Tjøtta.

Sammendrag

For å undersøke langtidsvirkning av ensidig grovfôrproduksjon ved langvarig eng i ulikt omløp, ble det anlagt feltforsøk på tre steder; Særheim (1968), Fureneset (1974) og Svanhovd (1969). Målet var å sammenligne ulike driftssystemer (beiting/slått og langvarig eng/eng i omløp) med hensyn til avling, kvalitet, botanisk sammensetning og jordtilstand. Forsøkene har vært gjennomført helt fram til i dag. Et utvalg har vurdert hvordan det foreliggende datamateriale kan publiseres, og om forsøksserien bør videreføres. Utvalget har estimert ressursbehovet for avsluttende publisering og for nødvendige tilleggsundersøkelser.

Sammendrag

Sturite et al. (2007) investigated growth and death of the major parts of white clover (Trifolium repens L. cv. "Snowy") plants in pure stand and in mixture with meadow fescue (Festuca pratensis L. cv. "Fure") in a combined plot and root window experiment in Norway (60°42"N, 10º51"E). Leaves, stolons and roots were tagged and their lifespan was monitored in harvested and non-harvested stands during two experimental years. The longevity of leaves and petioles ranged from 21 to 86 d (mean = 59 d). About 60% of the leaves produced during the growing season turned over before the autumn. Of the remaining leaves, 70-80 % were dead or had disappeared by the subsequent spring. The lifespan of sections of the main stolons ranged from 111 to over 677 d (mean = 411 d). In particular, stolon sections close to the parent fragment of undisturbed plants were long lived, while sections towards the terminal bud overwintered more poorly and had a much shorter lifespan. The longevity of roots was from 27 to 621 d (mean = 290 d) and was higher for roots appearing in spring and autumn than in summer. Harvesting significantly reduced the longevity of stolons and caused an increased fragmentation of the white clover plant but did not decrease leaf/petiole or root lifespan.

Sammendrag

Growth, death and N dynamics of leaves, stolons and roots of harvested and unharvested white clover (cv.""Snowy"") were studied in a pot (Sturite et al., 2006) and a combined plot and root window experiment in southeast Norway (Sturite et al., 2007). Leaves of undisturbed plants contained 1.5 g N pot-1 or 6 g N m-2 in late autumn (roughly assuming 4 plants m-2). About 60% of the leaves turned over within the growing season. Thus, in an established, undisturbed white clover stand, leaf turnover would contribute 9 g N m-2 during the growing season. For stolon and root segments tagged during the first growing season, 100% and 91%, respectively, were still present in late autumn. By the end of the second growing season, the corresponding values were 77% and 46%. Thus, dead stolons and roots contributed substantially more to N deposition in the soil in the second than in the first growing season. If taking the turnover of all plant organs into account, the gross N input to the soil-plant system during the two growing seasons would amount to 63 g N m-2. This corresponded to a 2.5-fold increase over the total N in the shoots harvested during the same period.

Sammendrag

In Norway, the goal of 15% organic food production within 2015 is too ambitious if the current growth rate of organic farmland is continued. Hence, a study of bottlenecks within organic farming systems in Northern Norway, and farmer"s preconditions to convert was conducted in spring 2007. A questionnaire was sent to certified and former certified organic farmers, and a control group of conventional farmers. For organic farmers the most important bottlenecks were public regulations and organic price premiums. Conventional farmers feared yield decrease, restricted forage availability and extra work. In 2008, interviews with selected farmers and officials in local municipalities were conducted to explore the reasons for large differences between certified organic farmland.

Sammendrag

Nitrogen (N) er kvantitativt det viktigste næringsstoff for vekst og reproduksjon. Nitrogenfikserende planter er avgjørende for å forsyne andre planter med N og for at fôr skal bli en bedre proteinkilde. Hvilke faktorer påvirker potensialet for biologisk nitrogenfiksering og hvordan overlever kløveren den lange nordnorske vinteren?

Sammendrag

Nitrogen (N) er kvantitativt det viktigste næringsstoff for vekst og reproduksjon. Nitrogenfikserende planter er avgjørende for å forsyne andre planter med N og for at fôr skal bli en bedre proteinkilde. Hvilke faktorer påvirker potensialet for biologisk nitrogenfiksering og hvordan overlever kløveren den lange nordnorske vinteren?

Sammendrag

Omlagt areal i 2008 (inkludert areal i karens) varierte fra 0 % til 24 % mellom de ulike kommunene i Nordland fylke. Derfor ble det undersøkt hvilke faktorer som ligger bak og som kan bidra til å forklare disse ulikhetene. Det ble valgt ut kommuner med lite (< 2.5 %) eller mye (> 10 %) omlagt økologisk areal og gjennomført telefonintervju med to til tre informanter fra hver kommune. De viktigste sammenhenger synes å være mellom omlagt areal og kommunal innsats; og øko-miljø i kommunen (smitteeffekt/naboeffekt); og holdning/interesse for økologisk landbruk blant bønder, lokale organisasjoner og myndigheter; og tilgang til ledig areal i kommunen.

Sammendrag

In order to improve the basis for utilizing white clover (Trifolium repens L) in northern agriculture, we studied the effects of defoliation intensity on spring growth in a sub-arctic climate in relation to carbohydrate and nodule status. White clover plants (cv Snowy) were studied in a pot experiment in the field on the coast of northern Norway from spring 2001 until spring 2002. The experiment was repeated with some modifications from spring 2002 until spring 2003. During the growing season from summer to autumn, the plants were totally stripped of leaves down to the stolon, cut at four or seven cm height or left undisturbed. The plants were sampled destructively in autumn, early spring and late spring and sorted into leaves, stolons and roots. The plant material was weighed and analysed for carbohydrate reserves and nodule number. Defoliation during the growing season resulted in reduced concentration of reserve carbohydrates in autumn and reduced winter survival of the stolons. The most severe defoliation treatment reduced the herbage growth in spring. In contrast, the two milder defoliation treatments had no effect on herbage growth during spring or on total plant dry matter and nodule status in late spring. In conclusion, moderate defoliation during the growing season had no effect on herbage growth the following spring nor on carbohydrate, nodule or dry matter status of the plant in late spring. Moderate defoliation increased spring growth and thereby also the nitrogen demand of the plants. This probably enhanced nodule formation and development of inactive to active nodules.

Sammendrag

Bruk av gras som fangvekster er en effektiv metode for å redusere tap av nitrogen fra kornareal enten det pløyes høst eller vår. Når graset får stå upløyd over vinteren dør en del før våren kommer, men nitrogen fra dette ser ikke ut til å nå vannveiene. Resultatene spriker litt mer når det gjelder hvorvidt bruk av fangvekster bidrar til redusert avrenning av fosfor.

Sammendrag

I denne artikkelen ser vi tilbake på noen nylig avsluttede prosjekt verdrørende bruk av fangvekster i korndyrkinga. Vi trekker konklusjoner basert på resultatene og vi viser til spørsmål som bør utredes nærmere. I tillegg presenterer vi nye data fra et forsøk i et lysimeteranlegg på Ås. Hensikten med dette forsøket var å evaluere i hvilken grad tidspunkt for nedpløying av fangvekster påvirker evnen til å holde nitrogen på jordet fra en vekstsesong til den neste.

Sammendrag

In order to improve the basis for utilising nitrogen (N) fixed by white clover (Trifolium repens L.) in northern agriculture, we studied how defoliation stress affected the N contents of major plant organs in late autumn, N losses during the winter and N accumulation in the following spring. Plants were established from stolon cuttings and transplanted to pots that were dug into the field at Apelsvoll Research Centre (60 degrees 42'N, 10 degrees 51' E) and at Holt Research Centre (69 degrees 40' N, 18 degrees 56' E) in spring 2001 and 2002. During the first growing season, the plants were totally stripped of leaves down to the stolon basis, cut at 4 cm height or left undisturbed. The plants were sampled destructively in late autumn, early spring the second year and after 6 weeks of new spring growth. The plant material was sorted into leaves, stolons and roots. Defoliation regime did not influence the total amount of leaf N harvested during and at the end of the first growing season. However, for intensively defoliated plants, the repeated leaf removal and subsequent regrowth occurred at the expense of stolon and root development and resulted in a 61-85% reduction in the total plant N present in late autumn and a 21-59% reduction in total accumulation of plant N (plant N present in autumn + previously harvested leaf N). During the winter, the net N loss from leaf tissue (N not recovered in living nor dead leaves in the spring) ranged from 57% to 74% of the N present in living leaves in the autumn, while N stored in stolons and roots was much better conserved. However, the winter loss of stolon N from severely defoliated plants (19%) was significantly larger than from leniently defoliated (12%) and non-defoliated plants (6%). Moreover, the fraction of stolon N determined as dead in the spring was 63% for severely defoliated as compared to 14% for non-defoliated plants. Accumulation in absolute terms of new leaf N during the spring was highly correlated to total plant N in early spring (R-2 = 0.86), but the growth rates relative to plant N present in early spring were not and, consequently, were similar for all treatments. The amount of inorganic N in the soil after snowmelt and the N uptake in plant root simulator probes (PRS (TM)) during the spring were small, suggesting that microbial immobilisation, leaching and gas emissions may have been important pathways for N lost from plant tissue.

Sammendrag

Intensive harvesting, as compared to no harvesting, favoured N transfer to the leaves on the expense of stolon and root biomass production. Independently of treatment, about 75 % of the N present in leaves in the autumn was lost, while N stored in stolons and, particularly, in roots was conserved much better. However, the stolons of intensively harvested plants seemed to be less winter hardy and lost more N (55%) than did undisturbed (21%) and less intensively harvested plants (13%). Relative plant growth and N uptake rate in spring were almost equal for all treatments. The amount of inorganic N in soil after snowmelt and mineralization of white clover-derived N during the spring was small, suggesting that leaching and gas emissions may have been important N pathways.

Sammendrag

To better understand N cycling in white clover (Trifolium repens L) stands under northern climate conditions, we studied how harvesting regime affects plant longevity and N content in late autumn, ability to conserve N during winter and the fate of the lost N. Several field experiments were performed throughout four consecutive years using white clover plants (cv "Snowy") that were established from stolon cuttings or seeds. During the growing season, plants were treated and sampled destructively in late autumn, early spring the second year and after six weeks of new spring growth. Dry weight and N concentration were measured on all fractions. On additional experiments the longevity of main plant organs were monitored during two years and seepage water percolating throughout the above ground plant biomass was collected during four years. For harvested plants the repeated leaf removal and subsequent regrowth came at the expense of stolon- and root development and resulted in a reduced total plant N content in late autumn. During winter, root N was quite stable, as certain root dormancy occured, while approximately 80 % of the N present in leaves in autumn was lost - independent of treatment. Short leaf lifespan (less than 100 days) indicated that leaves are not genetically programmed to survive winter. Losses of N from stolons were lower, however, harvesting regime affected both the longevity and N losses. The amount of inorganic N in soil after snowmelt and mineralization of white clover-derived N through spring was low indicating that leaching and gas emissions might be important N pathways. The 26 % of lost N was found in seepage water.

Sammendrag

I dette arbeidet, bruk av kvitkløver under nordlige klimaforhold har det blitt sett fra produksjons- og miljø perspektiver. De viktigste mål var å vurdere 1) på hvilket tidspunkt blader, stoloner og røtter dukker opp og omsettes; 2) i hvilken grad disse planteorganer taper N gjennom vinteren og hvor mye N gjenfinnes i sigevannet; 3) hvordan høsting påvirker både levetid av plantedeler og N dynamikken.

Sammendrag

Det er utviklet en ny analysemetode. Den er basert på bruk av 2, 3, 5 " trifenyltetrazolium klorid som farger metabolsk aktive celler, og bruk av bildebehandlings-programmet "WinRHIZO" for automatisk kvantifisering av aktive og inaktive deler av røttene.

Sammendrag

In a recently started research project with field experiments conducted under different climatic conditions, winter survival, spring growth and nitrogen dynamics of white clover are studied in relation to its physiological condition. Belowground biomass and the functioning and longevity of roots and nodules are especially focused. The physiological condition of the plants is manipulated by the use of different defoliation regimes during the growing season. The field experiments are situated at two locations; at Apelsvoll at 61°N, and in Tromsø, 69°N. The results show that the defoliation regimes affected the strategy of DM allocation in the white clover plants. The more frequent defoliation regime lead to increased allocation of photosynthates to leaves at the expense of roots and stolons. The defoliation regimes thus created a gradient in physiological condition of the plants