Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2009
Forfattere
Reidun Pommeresche Anne-Kristin LøesSammendrag
This paper presents Norwegian studies of earthworms (density, biomass, burrows density, species, juvenile to adult ratios) in arable soil in Norway conducted during the last 20 years. The effects of crop rotations, fertilization, soil tillage and compaction on earthworms are presented, based on various field experiments. Geophagous (soil eating) species such as Aporrectodea caliginosa and A. rosea dominate the earthworm fauna in Norwegian arable soil. Lumbricus terrestris is also present; in our studies even frequently found in an all-arable crop rotation with annual ploughing. In southern Norway, L. rubellus, and A. longa are commonly found. Earthworm density, recorded in autumn varied between 30 and 350 individuals m-2 in different studies, with the lowest values found in conventional all arable farming systems. One year of ley in the crop rotation increased earthworm burrow density, earthworm density and biomass. Even short-term leys for green manure had a positive effect, likely due to high clover content. Application of animal manure increased earthworm density and biomass. Because geophagous species prefer the upper soil layer, shallow ploughing (15 cm depth) was expected to be detrimental. However, the earthworm density and biomass was not lower with shallow as compared to deep ploughing (25 cm depth). With earthworm densities such as those found in farming systems with ley and animal manure, an estimated amount of 221 tonne of topsoil per hectare passes through the earthworm digestion system within one year. Field-collected geophagous earthworm casts had considerably higher concentrations of plant nutrients than bulk soil (28% higher concentration of Tot-N, 36-53% for PAL, 40%-59% for KAL). Earthworm casts are significant natural sources of plant nutrients, also in soils with high dominance of geophagous earthworm species.
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Siden begrepet økologisk landbruk ble lovbeskyttet gjennom EØS-avtalen i 1994 har antall økologiske gårder i Norge økt fra 561 til 2838 (november 2009). Et problem med begreper er at de ikke alltid gjenspeiler forestillingene våre. Si ordet «økologisk gård», og vi ser for oss frodige kløverenger, frittgående hønseflokker, kuer som vasser i hvit snø i januar og gulrøtter som vokser i kompostgjødslet, feit jord der meitemarken yngler og solsikkene blomstrer i grøftekanten. Det er imidlertid ingen krav om at hele gården skal legges om, så i praksis har en god del av disse gårdene en ganske begrenset økologisk produksjon. Hvert år siden 2002 har 150-200 bønder meldt seg ut av Debio, og dermed bidratt til inntrykket av at økologisk landbruk ikke er liv laga - i hvert fall ikke for bønder. Noen av gårdene som meldte seg ut, kom imidlertid aldri så langt som til å legge om noe som helst. Andre testet kanskje ut økodrift på litt av jorda, og fant ut at omlegging ikke var noe for dem. Andre igjen er ærlige på at de la om for å få kloa i ekstra tilskudd. Over tid kan en slik strategi koste mer enn den smaker. «Øko»-bonden vender tilbake til konvensjonell drift en erfaring rikere, men har bidratt til å gi økologien et dårlig rykte. Tilskuddsryttere er ikke noe man ønsker å bli identifisert med, og for eksempel ensidig økologisk korndyrking i Trøndelag har fått et dårlig ord på seg i denne sammenhengen. Selv med liten innsats og elendige avlinger kan økonomien bli bedre ved økologisk drift, på grunn av det ekstra arealtilskuddet. At noen slutter med økodrift er altså ikke nødvendigvis negativt for økologisk landbruk.
2008
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Recent in situ 13C studies suggest that lignin is not stabilised in soil in its polymerised form. However, the fate of its transformation products remains unknown. The objective of the present research was to provide the first comprehensive picture of the fate of lignin-derived C across its transformations processes: (1) C remaining as undecomposed lignin molecules, (2) C in newly formed humic substances, i.e. no longer identifiable as lignin-polymer C, (3) C in microbial biomass, (4) C mineralised as CO2, and (5) dissolved organic C. To achieve this objective, we designed an incubation experiment with 13C-labelled lignin where both elementary and molecular techniques were applied. Lignin was isolated from 13C labelled maize plants (13C-MMEL) and incubated in an agricultural soil for 44 weeks. Carbon mineralisation and stable isotope composition of the released CO2 were monitored throughout the incubation. Microbial utilisation of 13C-MMEL was measured seven times during the experiment. The turnover rate of the lignin polymer was assessed by 13C analysis of CuO oxidation products of soil lignin molecules. After 44 incubation weeks, 6.0% of initial 13C-MMEL carbon was mineralised, 0.8% was contained in the microbial biomass, and 0.1% was contained in dissolved organic C form. The compound-specific 13C data suggest that the remaining 93% were overwhelmingly in the form of untransformed lignin polymer. However, limited transformation into other humic substances potentially occurred, but could not be quantified because the yield of the CuO oxidation method proved somewhat variable with incubation time. The initial bacterial growth yield efficiency for MMEL was 31% and rapidly decreased to plateau of 8%. A two-pool first-order kinetics model suggested that the vast majority (97%) of MMEL lignin had a turnover time of about 25 years, which is similar to field-estimated turnover times for soil-extractable lignin but much longer than estimated turnover times for fresh plant-residue lignin. We conclude that natural lignin structures isolated from plants are rather unreactive in soil, either due to the lack of easily available organic matter for co-metabolism or due to enhanced adsorption properties. The data also suggest that fairly undecomposed lignin structures are the main reservoir of lignin-derived C in soils.
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Forfattere
Maja Bojesen Mekjell Meland Stein Harald HjeltnesSammendrag
Fruktdyrking er en langsiktig produksjon med store etableringskostnader. Forståelig nok har ingen dyrker lyst til å satse på ukjente sorter som det er usikkert om vil bli godt mottatt av omsetning og forbruker. Norsk kjernefruktproduksjon har derfor hatt lite fornying i sortimentet de siste årene. Et nytt prosjekt skal forsøke å rette opp på dette. Prosjektet er et samarbeide mellom fruktdyrkere, omsetningen, forsøksringene og forskningen.
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Due to a late harvesting season compared to that found in other European countries, the sweet cherry industry in Norway is now expanding, aiming for export markets. Cultivars producing high quality fruit that ripen late (late July and throughout August) and that are suitable to grow in high density production systems are sought. In addition, early ripening cultivars are sought for local marketing in early and middle July. Testing cultivars and advanced selections has been carried out at Ullensvang Research Centre since 1959. During the last decade, 130 cultivars and advanced selections have been included in the testing program. Important parameters like fruit size, fruit firmness, low fruit cracking, high and precocious yield, fresh appearance and good flavour have been evaluated. Based on the results from this testing program, the following cultivars are currently recommended: a) for early season: `Burlat", `Moreau" and `Merchant", b) for mid-season: `Giorgia", `Chelan", `Samba", `Techlovan" and `Van", c) for late season: `Lapins", `Kordia", `Regina" and `Sweetheart".