Sammendrag

Denne rapporten beskriver alle prosesser som er utarbeidet innenfor datafangst, dataforvaltning, bearbeiding og analyse samt formidling i implementeringsfasen av et nytt jordovervåkingsprogram for jordbruksjord i Norge. Rapporten inneholder detaljerte planer for hvordan jordinformasjon fra ulike indikatorer skal innhentes, analyseres og bearbeides slik at tilstand og endring i jordsmonnet kan overvåkes. Programmet vil danne grunnlaget for landsdekkende jordinformasjon som muliggjør en vurdering av jordsmonnets status og endring for de fem truslene man har identifisert for norsk jordbruksjord: erosjon, jordpakking, tap av organisk materiale, tap av jordbiodiversitet og forurensning.

Sammendrag

Som en del av prosjektet Våronn i fangvekster (2018−2022) finansiert av Klima- og miljøprogrammet i Landbruksdirektoratet har vi gjennomført en spørreundersøkelse blant kornprodusenter der målet var å 1) innhente og formidle erfaringer med dyrking av fangvekster, 2) finne ut hva som motiverer til eller hindrer bruk av fangvekster i kornproduksjonen og 3) avdekke kunnskapsbehov. Undersøkelsen viser at fangvekster blir brukt i forbindelse med vårkorn, høstkorn og andre åkervekster. Fangvekster praktiseres i vel så stor grad i allsidige vekstskifter som ved bare korndyrking. Undersøkelsen viser god oppslutning om hensikten med fangvekster, uavhengig av om kornprodusentene dyrket fangvekster eller ikke. Mange vurderer å dyrke fangvekster. Mangel på kunnskap om dyrkingsstrategier, ugrasproblematikk, frykt for utfordringer ved tresking, merarbeid og dårligere lønnsomhet er årsaker som oppgis til at de ikke dyrker fangvekster. Det er behov for å utvikle bærekraftige dyrkingsstrategier for bruk av fangvekster i allsidige vekstskifter med redusert jordarbeiding.

Sammendrag

In Norway, Fusarium diseases and associated mycotoxin contamination in spring oats occasionally cause problems for growers, livestock producers and the food and feed industries. Besides weather factors, such as rainfall and temperature in the critical periods around flowering and before harvest, inoculum production and disease development are influenced by agricultural practices. The occurrence of Fusarium graminearum and DON in oat grain lots do not generally correlate with that of Fusarium langsethiae and HT-2/T-2-toxins. Therefore, to develop a robust disease management strategy, there is a need to reveal the influence of weather and agricultural practice on disease development in oats for both these fungal species. Through various research projects NIBIO researchers have performed field trials to study the effects of straw management, tillage practice, cultivar, and chemical and biological control treatments on the development of Fusarium spp. and mycotoxins in oats. In particular we have investigated whether the amount of straw residues and tillage practice influences the survival of Fusarium spp. in residues, and the subsequent Fusarium spp. infection of the harvested grains. In addition, Fusarium spp. DNA and mycotoxin content (DON and HT-2/T-2) have been analysed in oats from current official cultivar trials. This work has been a collaboration between NIBIO and the Norwegian Agricultural Extension Service. Results will be presented on the Fusarium spp. and mycotoxin contamination of grains harvested from oats grown under various agricultural practices. High incidence of Fusarium avenaceum are often observed in harvested grains as well as straw residues. Fusarium graminearum is also commonly detected. Despite the high concentrations of F. langsethiae DNA and HT-2/T-2 toxins sometimes recorded in oat grain, only low levels of F. langsethiae have been detected in crop residues and air samples. We speculate that the life cycle of F. langsethiae differs from those of F. graminearum and F. avenaceum with regards to survival, inoculum production and dispersal.

Sammendrag

Tap av organisk materiale, jordpakking og erosjon truer jordhelsa på kornareal. Problemer med dette vil antagelig øke i et våtere klima og medføre store kostnader for både gårdbrukere og samfunn. Fremover må vi passe på å stabilisere erosjonsutsatt jordoverflate og sikre en god infiltrasjon av nedbør. På kornareal er lav årlig tilførsel av karbon en begrensende faktor for aggregering og stabilisering, men dette kan forbedres ved å beholde halmen på jordet eller bruke en tilpasset fangvekststrategi. En bør trolig skjevfordele tilført organisk materiale mer mot jordas overflate og dermed stimulere mikrobiell aktivitet i jordas toppsjikt. Da må en minimere jordarbeidingsintensiteten. Slik redusert jordarbeiding fører også til utvikling av et kontinuerlig poresystem nedover i profilet som kan øke infiltrasjonen etter kraftige nedbørsepisoder og dermed bidra til å dempe flomtopper. Store mengder plantemateriale ved jordoverflaten gir imidlertid også noen utfordringer. Det trengs økt kunnskap om ugrasbekjempelse, spesielt i et scenario der glyfosat blir forbudt. Minimal jordarbeiding med planterester på jordoverflaten kan også øke angrep av sopp. Integrerte plantevernstrategier bør identifisere arter og sorter av matplanter og fangvekster som kan bidra til å begrense forekomst av patogener i jord og halmrester. Bedre jordhelse på kornareal er en tverrfaglig utfordring og krever en varig endring av dagens dyrkingspraksis.

Sammendrag

Rapporten er en del av et forprosjekt som skal gi grunnlag for utarbeidelse av en handlingsplan for god nitrogenutnyttelse i jordbruket. Det er beskrevet en rekke tiltak med potensiale for bedre utnyttelse av nitrogenressursene som forvaltes i norsk jordbruk. For mer detaljer henvises til teksten i rapporten og oversikten i tabell 1. Se side 5 for utfyllende sammendrag.

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Sammendrag

A series of 131I tracer experiments have been conducted at two research stations in Norway, one coastal and one inland to study radioiodine transfer and dynamics in boreal, agricultural ecosystems. The hypothesis tested was that site specific and climatological factors, along with growth stage, would influence foliar uptake of 131I by grass and its subsequent loss. Results showed that the interception fraction varied widely, ranging from 0.007 to 0.83 over all experiments, and showing a strong positive correlation with biomass and stage of growth. The experimental results were compared to various models currently used to predict interception fractions and weathering loss. Results provided by interception models varied in the range of 0.5–2 times of the observed values. Regarding weathering loss, it was demonstrated that double exponential models provided a better fit with the experimental results than single exponential models. Normalising the data activity per unit area to remove bio-dilution effects, and assuming a constant single loss rate gave weathering half-times of 22.8 ± 38.3 and 10.2 ± 8.2 days for the inland and coastal site, respectively. Whilst stable iodine concentrations in grass and soil were significantly higher (by approximately a factor of 5 and 7 times for grass and soil respectively) at the coastal compared to the inland site, it was not possible to deconvolute the influence of this factor on the temporal behaviour of 131I. Nonetheless, stable iodine data allowed us to establish an upper bound on the soil to plant transfer of radioiodine via root uptake and to establish that the pathway was of minor importance in defining 131I activity concentrations in grass compared to direct contamination via interception. Climatological factors (precipitation, wind-speed and temperature) appeared to affect the dynamics of 131I in the system, however the decomposition of these collective influences into specific contributions from each factor remains unresolved and requires further study. The newly acquired data on the interception and weathering of radioiodine in boreal, agricultural ecosystems and the reparametrized models developed from this, substantially improve the toolbox available for Norwegian emergency preparedness in the event of a nuclear accident.

Sammendrag

Som en del av prosjektet Presisjonshektaren ved NIBIO Senter for Presisjonsjordbruk har det gjennom 2021 og 2022 blitt utført et demonstrasjonsforsøk hvor det ble prøvd ulike verktøy til jordkartlegging på et tilsynelatende homogent skifte gjennom en sesong. Denne rapporten oppsummerer dette arbeidet ved å beskrive resultatet fra kartleggingen og ser på sammenhenger mellom kartleggingsresultater og avlingsnivå. Resultatene viser at også innenfor et skifte som ser homogent ut, finnes det en god del variasjon på grunn av topografi (Figur 2) og forskjeller i jordegenskaper (Figur 8 - Figur 11) som kan føre til en betydelig variasjon i avling og proteininnhold (Figur 20 og Figur 21). Dette viser at dersom man skal kartlegge jorda som basis for presisjonstildeling av innsatsfaktorer, kan det være verdt å vurdere å ta jordprøver noe tettere enn den generelle anbefalingen. I dette forsøket viste høsteprøvene et spenn i kornavling tilsvarende 560-800 kg per daa minimum. Proteininnholdet varierte fra 11,2 til 13 %. Siden dette forsøket ble gjennomført som et ettårig forsøk uten gjentak, er det ikke mulig å konkludere med noen årsakssammenheng mellom de forskjellige variablene som er målt. Det er likevel observert interessante samvariasjoner mellom forskjellige typer kartlegging. Det kan være interessant å gjøre mer detaljerte forsøk for å undersøke disse nærmere på et senere tidspunkt. Ved konvensjonell, uniform dyrkingspraksis, vil hele skiftet behandles likt ved for eksempel gjødsling og jordarbeiding. Dette fører til at ikke alle områder blir behandlet etter behov og potensiale. Ved homogen gjødsling vil noen områder få mer gjødsel enn nødvendig. Dette reduserer utnyttelsen av innsatsfaktorene og kan føre til økt miljøbelastning og kostnader. Samtidig vil andre områder få for lite gjødsel, noe som kan begrense avlingspotensialet og produksjonseffektiviteten. Omfanget av variasjonen i dette forsøket illustrerer derfor behovet for stedspesifikk behandling. Med høye priser på innsatsfaktorer er det et stort innsparingspotensial i å behandle de ulike områdene ut fra behov og potensiale. Det finnes mange muligheter for kartlegging av åkeren, og gårdbrukeren møter mange ulike tilbud. Det er svært viktig at gårdbrukeren før hen benytter seg av et slikt tilbud ber om dokumentasjon på kvalitet og kalibrering for norske forhold. Ved omfattende kartlegging genereres også store mengder data som må ivaretas på en god måte for å kunne være til nytte for bonden. Som en del av arbeidet med Presisjonshektaren er det også utarbeidet en oversikt over forskjellige såkalte «Farm Management Information Systems» (FMIS) – informasjonsstyringssystemer for gårdsbruk (NIBIO Rapport – FMIS for norske gårdbrukere).) Et ettårig forsøk slik som det som er gjennomført her gir ikke muligheter for å konkludere om hvilken kartleggingsmetode som egner seg best. Resultatene og erfaringen fra det første året med forsøk på ‘Presisjonshektaren’ viser behovet for utvidet forskning på praktisk anvendelse av metodene for kartlegging for å prøve metodene gjennom flere sesonger og på ulike plasser for å også dekke variasjon i jordtype og klimatiske forhold. NIBIO driver med en rekke spennende forsøk innom presisionslandbruk i grensesnittet mellom agronomi, jordfag, plantedyrking og teknologi og dette blir også tema i nye forsøk i tida framover. Følg med på NIBIO’s aktivitet innenfor fagområdet: www.nibio.no https://precisionag.no/nb/hjem/

Sammendrag

Klimaendringer er i Norge ventet å gi en lenger vekstsesong, men også risiko for mer ekstremvær som tørke og episoder med store nedbørsmengder. Dette vil påvirke planteproduksjonen og behovet for tilpasninger. Dette faktaarket omhandler strategier for klimatilpasning for byggdyrking på lettleire i Hedmark.

Sammendrag

Klimaendringer er i Norge ventet å gi en lenger vekstsesong som kan øke muligheten for å etablere høstkorn i tide om høsten og dermed øke høstkornarealet. Det er også forventet mer ekstremvær som store nedbørsmengder og tørke. Det kan gi utfordringer i forhold til etablering av høstkornet, påvirke planteproduksjonen og behovet for tilpasninger. Dette faktaarket omhandler strategier for klimatilpasning for høstkornproduksjon på leirjord i Østfold.

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Sammendrag

Soil compaction (SC) is a major threat for agriculture in Europe that affects many ecosystem functions, such as water and air circulation in soils, root growth, and crop production. Our objective was to present the results from five short-term (<5 years) case studies located along the north–south and east–west gradients and conducted within the SoilCare project using soil-improving cropping systems (SICSs) for mitigating topsoil and subsoil SC. Two study sites (SSs) focused on natural subsoil (˃25 cm) compaction using subsoiling tillage treatments to depths of 35 cm (Sweden) and 60 cm (Romania). The other SSs addressed both topsoil and subsoil SC (˃25 cm, Norway and United Kingdom; ˃30 cm, Italy) using deep-rooted bio-drilling crops and different tillage types or a combination of both. Each SS evaluated the effectiveness of the SICSs by measuring the soil physical properties, and we calculated SC indices. The SICSs showed promising results—for example, alfalfa in Norway showed good potential for alleviating SC (the subsoil density decreased from 1.69 to 1.45 g cm−1) and subsoiling at the Swedish SS improved root penetration into the subsoil by about 10 cm—but the effects of SICSs on yields were generally small. These case studies also reflected difficulties in implementing SICSs, some of which are under development, and we discuss methodological issues for measuring their effectiveness. There is a need for refining these SICSs and for evaluating their longer-term effect under a wider range of pedoclimatic conditions.

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Frequent occurrences of high levels of Fusarium mycotoxins have been recorded in Norwegian oat grain. To elucidate the influence of tillage operations on the development of Fusarium and mycotoxins in oat grain, we conducted tillage trials with continuous oats at two locations in southeast Norway. We have previously presented the content of Fusarium DNA detected in straw residues and air samples from these fields. Grain harvested from ploughed plots had lower levels of Fusarium langsethiae DNA and HT-2 and T-2 toxins (HT2 + T2) compared to grain from harrowed plots. Our results indicate that the risk of F. langsethiae and HT2 + T2 contamination of oats is reduced with increasing tillage intensity. No distinct influence of tillage on the DNA concentration of Fusarium graminearum and Fusarium avenaceum in the harvested grain was observed. In contrast to F. graminearum and F. avenaceum, only limited contents of F. langsethiae DNA were observed in straw residues and air samples. Still, considerable concentrations of F. langsethiae DNA and HT2 + T2 were recorded in oat grain harvested from these fields. We speculate that the life cycle of F. langsethiae differs from those of F. graminearum and F. avenaceum with regard to survival, inoculum production and dispersal.

Sammendrag

SoilCare er et femårig forskningsprosjekt finansiert av EUs Horisont2020-program som startet 1. mars 2016 og avsluttes 31. august 2021. Prosjektet er et samarbeid mellom 28 europeiske partnere med studieområder i 16 ulike europeiske land. Målet med prosjektet var å undersøke potensialet til jordforbedrende tiltak, samt identifisere og teste områdespesifikke jordforbedrende dyrkingssystemer med antatt positiv effekt på lønnsomhet og bærekraft i Europa. NIBIO er norsk partner i prosjektet, med studieområder på Østlandet (Viken og Innlandet), og har testet metoder for å bedre jordkvaliteten i Norge i samarbeid med Norges landbruksrådgivning (NLR). Denne samlerapporten beskriver arbeidsprosessene og oppsummerer resultater fra de norske studieområdene, med valg/prioritering av interessenter, idéverksteder for å identifisere årsaker til redusert jordkvalitet og mulige tiltak, utprøving av tiltak i feltforsøk, og medvirkning for å utvikle strategier for videre implementering, samt evaluering av resultater. Basert på resultatene fra studieområdene gis det følgende anbefalinger: utarbeide et mer fleksibelt system for økonomiske virkemidler, revidere de eksisterende virkemidlene og inkludere mer ambisiøse og langsiktige mål, lage målsettinger for jord og god jordforvaltning i eksisterende lovgivning, samt etablere mekanismer for effektiv kunnskapsformidling og utveksling.

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The main objective was to evaluate to what extent subsoil compaction on an arable clay soil (Stagnosol (Drainic)) may be alleviated after 5 years under the climate conditions in South-East Norway. Therefore, field plots which had been ploughed and under minimum tillage were compacted through wheel impact (10x) with a 6.6 Mg wheel load. Samples were taken from the ‘compacted’ and ‘non-compacted reference’ treatments at depths of 40 and 60 cm both before and directly after compaction and again 5 years later. The soil physical parameters revealed that pre-compression stress, bulk density, air capacity, air conductivity and saturated hydraulic conductivity at depths of 40 and 60 cm were impaired by compaction, especially under ploughed. After 5 years, bulk density and pre-compression stress remained almost unchanged, while air capacity, air conductivity and saturated hydraulic conductivity had increased at both the 40 and 60 cm depth on both plots as compared to the compacted state and to R for the most part, indicating the recovery of the soil structure in the subsoil. The compaction status evaluated by the ‘compaction verification tool’ indicates the relative reduction of ‘harmful soil compaction’ (after wheel impact) with a change towards ‘slightly harmful compaction’ for the most part with an as yet limited saturated hydraulic conductivity at both depths after 5 years.

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This study aims to understand the environmental factors, focusing on rain and fungal infection, affecting the assembly of glutenin polymers during grain maturation. Spring wheat was grown in the field and grains were sampled from 50% grain moisture until maturity. Grain moisture content, protein content, size of glutenin polymers, the presence of proteases, and the amount of DNA from common wheat pathogenic fungi were analysed. Rain influenced the rate of grain desiccation that occurred parallel to the rate of glutenin polymer assembly. Rapid desiccation contributed to faster glutenin polymer assembly than gradual desiccation. Severe reduction in the glutenin polymer size coincided with increased grain moisture due to rain. Furthermore, increased fungal DNA followed by presence of gluten-degrading proteases was observed in the grain after humid conditions. The presence of gluten-degrading proteases was presumably involved in reducing the size of glutenin polymers in grain. Our study gave new insight into how environmental conditions could be associated with the assembly of glutenin polymers during grain maturation. The results suggest that rain and/or fungal proteases play an important role in reducing the molecular size of glutenin polymers.

Sammendrag

To mitigate the risk of erosion and nutrient runoff, reduced tillage has become more prevalent in Norway. Within within recent decades, there have been some years with relatively high occurrence of Fusarium head blight and mycotoxins in Norwegian cereal grain. This is thought to have been caused by an increased inoculum potential (IP) of Fusarium spp. due to larger amount of crop residues remaining on the soil surface, in combination with weather conditions promoting fungal growth and infection of cereal plants. The objective of this work was to elucidate the influence of different tillage practices on the IP of Fusarium spp. and the subsequent Fusarium-infection and mycotoxin contamination of spring wheat grain at harvest. Tillage trials were conducted at two locations in southeast Norway (Solør and Toten) over three years, 2010-2012. Residues of wheat from the previous year were collected in spring. Fusarium avenaceum and Fusarium graminearum were the most common Fusarium species recorded on wheat straw residues. IP was calculated as the percentage of the residues infested with Fusarium spp. multiplied by the proportion of the soil surface covered with residues. The IP of Fusarium spp. was lower in ploughed plots compared to those tilled with harrowing only. Ploughing in spring resulted in a similarly low IP as autumn ploughing. In contrast, harrowing in autumn generally reduced IP more than did spring harrowing. The mycotoxin levels in the harvested wheat were generally low, except for deoxynivalenol at high levels in Solør 2011. Despite a lower IP of ploughed versus harrowed plots, this was not reflected in the content of Fusarium and mycotoxins in harvested grain. The Fusarium species that dominated in the residues examined in this study were the same as those detected in the harvested grain, supporting the finding that residues are an important source of inoculum.

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An increase in cereal production in Norway is important for national food security and fulfilling the aim of increased food production. Since the early 1990’s, both reduced cereal area and stagnating yields have been reported. A sustainable yield increase on existing arable land is an important strategy to increase cereal production globally, but also in Norway.

Sammendrag

Ønsket om forbedret effektivitet fører til bruk av stadig større og tyngre maskiner, og det gir økt risiko for jordpakking. Økende andel leiekjøring og lengre transportavstander gjør at de store, effektive maskinene ofte brukes under fuktige forhold når jorda ikke er laglig. Skadene på jordstrukturen som følge av dette kan redusere avlingene betydelig og ha negative miljøeffekter. Jordpakking er blant hovedårsakene til at avlingene har stagnert i mange av verdens største kornområder de seinere årene. Klimaforandringer i Norge vil trolig føre til fuktigere forhold og gir enda større fare for jordpakking. Det er derfor viktig å ivareta jordstrukturen i størst mulig grad, for å sikre vanninfiltrasjon og gode vekstbetingelser for kulturplantene gjennom sesongen.

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The objective of this study was to evaluate the effect of wheeling with two different wheel loads (1.7 and 2.8 Mg) and contrasting wheeling intensities (1x and 10x) on the bearing capacity of a Stagnosol derived from silty alluvial deposits. Soil strength was assessed by laboratory measurements of the precompression stress in topsoil (20 cm) and subsoil (40 and 60 cm) samples. Stress propagation, as well as elastic and plastic deformation during wheeling were measured in the field with combined stress state (SST) and displacement transducers (DTS). We also present results from soil physical analyses (bulk density, air capacity, saturated hydraulic conductivity) and barley yields from the first two years after the compaction. Although the wheel loads used were comparatively small, typical for the machinery used in Norway, the results show that both increased wheel load and wheeling intensity had negative effects on soil physical parameters especially in the topsoil but with similar tendencies also in the subsoil. Stress propagation was detected down to 60 cm depth (SST). The first wheeling was most harmful, but all wheelings led to accumulative plastic soil deformation (DTS). Under the workable conditions in this trial, increased wheeling with a small machine was more harmful to soil structure than a single wheeling with a heavier machine. However, the yields in the first two years after the compaction did not show any negative effect of the compaction.

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Europe accounts for around 20% of the global cereal production and is a net exporter of ca. 15% of that production. Increasing global demand for cereals justifies questions as to where and by how much Europe’s production can be increased to meet future global market demands, and how much additional nitrogen (N) crops would require. The latter is important as environmental concern and legislation are equally important as production aims in Europe. Here, we used a country-by-country, bottom-up approach to establish statistical estimates of actual grain yield, and compare these to modelled estimates of potential yields for either irrigated or rainfed conditions. In this way, we identified the yield gaps and the opportunities for increased cereal production for wheat, barley and maize, which represent 90% of the cereals grown in Europe. The combined mean annual yield gap of wheat, barley, maize was 239 Mt, or 42% of the yield potential. The national yield gaps ranged between 10 and 70%, with small gaps in many north-western European countries, and large gaps in eastern and south-western Europe. Yield gaps for rainfed and irrigated maize were consistently lower than those of wheat and barley. If the yield gaps of maize, wheat and barley would be reduced from 42% to 20% of potential yields, this would increase annual cereal production by 128 Mt (39%). Potential for higher cereal production exists predominantly in Eastern Europe, and half of Europe’s potential increase is located in Ukraine, Romania and Poland. Unlocking the identified potential for production growth requires a substantial increase of the crop N uptake of 4.8 Mt. Across Europe, the average N uptake gaps, to achieve 80% of the yield potential, were 87, 77 and 43 kg N ha−1 for wheat, barley and maize, respectively. Emphasis on increasing the N use efficiency is necessary to minimize the need for additional N inputs. Whether yield gap reduction is desirable and feasible is a matter of balancing Europe’s role in global food security, farm economic objectives and environmental targets.

Sammendrag

I Norge er det betydelige variasjoner i vær og klima mellom og innen ulike landsdeler. Temperaturene er høyere sammenliknet med andre områder på samme breddegrader på grunn av gunstige luft- og havstrømmer. Forholdene for kornproduksjon er likevel marginale, siden vekstsesongen er kort og relativt våt, noe som fører til et relativt lavt avlingsnivå. I følge klimamodellene er Norge blant de få områdene i Europa der en forventer en positiv effekt av klimaendringer på planteproduksjonen, men økt nedbør og mer ekstremvær er utfordringer som må håndteres.

Sammendrag

Selv med god agronomi kan jordpakking bli et problem. Forskere i NIBIO har sett på hvordan man kan få tilbake vanninfiltrasjonen og lufttilførselen til jorda igjen. Og løsningen kan ligge i et samarbeid med plantene.

Sammendrag

Selv med god agronomi kan jordpakking bli et problem. Forskere i Nibio har sett på hvordan man kan få tilbake vanninfiltrasjonen og lufttilførselen til jorda igjen. Og løsningen kan ligge i et samarbeid med plantene.

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Sammendrag

På oppdrag fra Statens vegvesen har NIBIO delt inn jordbruksareal og dyrkbar jord etter den 5-delte verdiskalaen som benyttes i «Håndbok for onsekvensanalyser». Verdiklassifisering av jordbruksareal bygger på jordsmonnkart der det er tilgjengelig, og ellers på opplysninger fra AR5 og DMK. I områder uten jordsmonnkart vil det være nødvendig med supplerende undersøkelser for å gjøre en fullstendig verdivurdering. Dyrkbar jord er klassifisert etter opplysninger fra DMK og datasettet «dyrkbar jord». Verdikartene er tilgjengelige i kartinnsynsløsning, som WMS og for nedlasting. Faktorer som påvirker gjenstående jordbruksareal er redusert størrelse, form og tilgjengelighet. Riktige tiltak ved rigg- og anleggsområde på jordbruksareal er nødvendig for å unngå varige avlingsreduksjoner som følge av jordpakking.

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Sammendrag

Økt produksjon av korn er viktig for å øke matproduksjonen i Norge i tråd med landbrukspolitiske målsettinger. Men den norske kornproduksjonen er betydelig redusert siden 1990, både på grunn av redusert areal og fravær av avlingsframgang. Å øke avlingene per arealenhet vil være nødvendig for å snu trenden og å øke den norsk kornproduksjonen. I BIONÆR-prosjektet AGROPRO (Agronomi for økt matproduksjon. Utfordringer og muligheter) er det forsket på jord, jordkultur og samspillet mellom jord og planter for å oppnå økt avling med bærekraftige produksjonsmetoder. I denne rapporten beskrives kunnskapsstatus for et utvalg av agronomiske tiltak, og deres betydning for å oppnå økte kornavlinger. Arbeidet er gjennomført av forskere og andre nøkkelpersoner med ekspertise på fagområdene innen jord og jordarbeiding, hydrologi og drenering, kornproduksjon og avlingsfysiologi, kornsorter og planteforedling. For hvert agronomisk tiltak er det tatt utgangspunkt i kunnskapsstatus, resultater fra feltforsøk, og andre relevante rapporter og statistikker. For å kvantifisere mulige avlingsøkninger av tiltakene er det i tillegg brukt faglig skjønn som er utfordret i gruppediskusjoner. Rapporten konkluderer med at kornavlingene kan økes med 20-25% gjennom de forbedrede agronomiske tiltakene som er vurdert. Tiltak som forbedrer dyrkingsjordas kvalitet og som reduserer/forebygger jordpakking er særlig viktige, og legger grunnlaget for ytterligere økninger av andre tiltak.

Sammendrag

Four field trials (spring wheat and oats) were conducted (one on clay soil, one on loam soil and two on silt soil) for three years in important cereal growing districts, to investigate the influence of tillage regimes (ploughing versus reduced tillage in either autumn or spring) and straw management (removed and retained) on plant residue amounts, weed populations, soil structural parameters and cereal yields. The effect of tillage on soil structure varied, mainly due to the short trial period. In general, the amount of small soil aggregates increased with tillage intensity. Reduced soil tillage, and in some cases spring ploughing, gave significantly higher aggregate stability than autumn ploughing, thus providing protection against erosion. However, decreasing tillage intensity increased the amounts of weeds, particularly of Poa annua on silt soil. Straw treatment only slightly affected yields, while effects of tillage varied between both year and location. Reduced tillage, compared to ploughing, gave only small yield differences on loam soil, while it was superior on clay soil and inferior on silt soil. Our results suggest that shallow spring ploughing is a good alternative to autumn ploughing, since it gave comparable yields, better protection against erosion and was nearly as effective against weeds.

Sammendrag

Abstract The object of the first study was to evaluate effects of long-term tillage regimes (ploughing- P and minimum tillage- M) on the bearing capacity of a clay loam soil and to determine the effects of wheeling with different wheel loads (4.1 Mg; 6.6 Mg) and wheeling frequencies (1x, 10x) of two slurry tankers on the soil’s functional parameters and crop yields. Paper I includes laboratory measurements of the precompression stress (Pc) to determine soil strength at -6 kPa in top- (20 cm) and subsoil (40 and 60 cm). Further, a combined stress-state and displacement transducer system was used to determine major principal stress (σ1) and vertical and horizontal soil deformation in the field. It was the first time this technique has been used under the climatic and farming conditions in Norway. The results show that the M plot had in the topsoil 74% higher Pc than the P plot, whilst the differences were less distinct in the subsoil. Wheeling increased Pc at all soil depths. Compared to ploughing, higher Pc in the upper layer of the M plot led on average to 60% (light tanker) and 48% (heavy tanker) reductions in the σ1 values. The extent of σ1 was dependent on the ground pressure in the topsoil. The first pass of a wheel caused the greatest damage in some cases, but all wheelings led to accumulative plastic deformation in both vertical and horizontal directions. The results show that soil water content is an important factor influencing bearing capacity. Wheeling with high intensity would have exceeded Pc in all cases in moist soil (matric potential -6 kPa). Drier soil (-100 kPa), in combination with minimum tillage, limited the occurrence of stresses exceeding Pc in the upper soil layer. The effects of tillage, wheel load and wheeling intensity on the hydraulic properties of this soil are described in Paper II. Soil physical analyses and a compaction verification tool (CVT) were used in order to assess the extent of damage to soil structure. In addition, grain yields are presented for the ten years before and two years after the compaction study. The yields in the period before compaction were strongly affected by tillage, ploughing giving on average 24% higher yield than direct drilling. Yields after compaction were affected by both previous tillage and compaction intensity. In the first year, single wheeling on the P plot gave 23% and 28% yield reductions with 4.1 Mg and 6.6 Mg wheel loads, respectively, whilst multiple wheeling gave 14 % reduction at 6.6 Mg wheel load. Yield reductions on the M plot ranged from 63% (1x wheeling with 4.1 Mg) to 100% (10x wheeling with 6.6 Mg). Similar trends were found in the second year. Soil physical data indicated that all wheeling led to changes in both top- and subsoil on both tillage plots. However, effects in the subsoil were partly masked by the soil’s high initial bulk density. The CVT suggested harmful compaction on both plots, with the M plot being less affected than the P plot. However, yield results did not support this conclusion, suggesting that other factors limited yields on the M plot. The second study was part of a multidisciplinary project addressing Fusarium aspects related to crop management, plant breeding and animal productivity. The main object of Paper III was to compare effects of ploughing versus reduced tillage and straw removal versus retention, on the amounts of plant residue, weed populations, soil structural parameters and cereal yields in four 3-year tillage trials (spring oats and spring wheat) on  soils (clay loam, loam and silt) representative of cereal-growing in Norway. The methods included measuring straw residue cover, analyses of soil physical parameters, weediness, as well as crop yields and quality. The results showed that the more intensive the tillage, the higher the amount of small and the lower the amount of large soil aggregates. Reduced soil tillage, and in some cases spring ploughing, gave significantly higher aggregate stability than autumn ploughing, thus providing good protection against erosion. However, decreasing soil tillage intensity generally increased the amounts of surface residues and weeds. Crop rotation with oilseeds also led to a higher amount of weeds, both in the oilseed itself and in cereals the following year. Straw treatment affected yields to only a small degree, whilst the effects of soil tillage varied between both year and soil type. There were only small yield differences between tillage systems on loam soil, whilst reduced soil tillage was superior on clay soil and inferior on silt soil. Our results suggest that shallow spring ploughing is a good alternative to autumn ploughing, as it gave comparable yields and better protection against erosion, and was nearly as effective against weeds. In Paper IV the influence of the various tillage regimes on the inoculum potential and dispersal of Fusarium spp. was evaluated. In order to assess the amount of Fusarium spp. on straw residues, samples from the previous year were collected after sowing. Inoculum potential was calculated as the percentage of the residues infested with Fusarium spp. multiplied by the proportion of the soil surface covered with residues. For the assessment of Fusarium inoculum transported over long distances, air samples were collected in spore traps. This is the first report in Norway of Fusarium species DNA collected in air samples above cereal fields. The results confirm that residues are an important source of inoculum and the inoculum potential of Fusarium spp. was significantly lower in ploughed plots compared to those with harrowing only. No differences in the inoculum potential were found between ploughing in spring and autumn, whereas harrowing in autumn generally reduced it more than did spring harrowing. Fusarium DNA was mainly detected in the samples collected from heading onwards, and the dispersal increased after rainy periods.

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Sammendrag

Verification of traffic-induced soil compaction after long-term ploughing and ten years minimum tillage on clay loam soil in South-East Norway T. Seehusen, T. Børresen, B.I. Rostad, H. Fleige, A. Zink and H. Riley Abstract Grain yields are presented from a 10-year field trial with four tillage regimes (annual ploughing, harrowing only, ploughing/harrowing alternate years, minimum tillage) on clay loam. We also present soil physical analyses and use the compaction verification tool (CVT) to assess compaction on plots with annual ploughing and minimum tillage, after using slurry tankers with contrasting wheel loads (4.1 Mg, 6.6 Mg) and wheeling intensities (1x/10x) in the 11th trial year, and yields monitored two years after compaction. Winter wheat yields in the period before compaction were strongly affected by tillage, with annual ploughing giving on average 24% higher yield than direct drilling. Both wheat and oats were far less affected in treatments with harrowing only or ploughing/harrowing alternate years, on average within 6% of annual ploughing. Yields after compaction were affected by both previous tillage and compaction intensity. In the first year, single wheeling after annual ploughing gave 23% yield reduction with 4.1 Mg wheel load and 28% reduction with 6.6 Mg wheel load, whilst multiple wheeling gave 14 % reduction at 6.6 Mg wheel load. Yield reductions after minimum tillage ranged from 63% (single wheeling with 4.1 Mg) to 100% (multiple wheeling with 6.6 Mg). Similar trends were found in the second year. The soil physical data indicated that all wheeling led to changes in bulk density, pore sizes and permeability in both topsoil and subsoil on both sampled tillage plots. However, effects in the subsoil were partly masked by the soil’s high initial bulk density, partly due to its high clay content. The CVT, which plots air capacity against hydraulic conductivity, suggested some harmful compaction on both plots, with the minimum tillage plot being less affected than the ploughed plot. However, yield results did not support this conclusion, indicating that other factors limited yields on the minimum tilled plot. Keywords: long term contrasting soil tillage, yield results, slurry tanker, wheel load, wheeling intensity, compaction verification tool.