Lars Olav Brandsæter
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(+47) 901 09 435
lars.olav.brandsaeter@nibio.no
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Høgskoleveien 7, 1433 Ås
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Forfattere
Björn Ringselle Benedikte Watne Oliver Therese With Berge Inger Sundheim Fløistad Liv Berge Lars Olav BrandsæterSammendrag
Many herbaceous perennial plant species gain significant competitive advantages from their underground creeping storage and proliferation organs (CR), making them more likely to become successful weeds or invasive plants. To develop efficient control methods against such invasive or weedy creeping perennial plants, it is necessary to identify when the dry weight minimum of their CR (CR DWmin) occurs. Moreover, it is of interest to determine how the timing of CR DWmin differs in species with different light requirements at different light levels. The CR DWmin of Aegopodium podagraria, Elymus repens and Sonchus arvensis were studied in climate chambers under two light levels (100 and 250 μmol m−2 s−1), and Reynoutria japonica, R. sachaliensis and R. × bohemica under one light level (250 μmol m−2 s−1). Under 250 μmol m−2 s−1, the CR DWmin occurred before one fully developed leaf in R. sachaliensis, around 1–2 leaves in A. podagraria and E. repens and around four leaves in S. arvensis, R. japonica and R. × bohemica. In addition to reducing growth in all species, less light resulted in a higher shoot mass fraction in E. repens and S. arvensis, but not A. podagraria; and it delayed the CR DWmin in E. repens, but not S. arvensis. Only 65% of planted A. podagragra rhizomes produced shoots. Beyond the CR DWmin, Reynoutria spp. reinvested in their old CR, while the other species primarily produced new CR. We conclude that A. podagraria, R. sachaliensis and E. repens are vulnerable to control efforts at an earlier developmental stage than S. arvensis, R. japonica and R. × bohemica.
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Haftamu Gebretsadik Gebrehiwot Jens Bernt Aune Ole Martin Eklo Torfinn Torp Lars Olav BrandsæterSammendrag
Allelopathic potential of 10 teff varieties was assessed in laboratory experimentation (conducted in NIBIO, Norway), and determined with an agar-based bioassay using ryegrass and radish as model weeds. Field experiments were conducted in Tigray, Ethiopia during 2015 and 2016 to identify the most important agronomic traits of teff contributing to its weed competitive ability. A split plot design with three blocks was used considering hand weeding as the main plot and varieties as the subplot. Randomized complete block design (RCBD) with four blocks was used in the laboratory experiment. The highest potential allelopathic activity (PAA) and specific potential allelopathic activity (SPAA) were recorded from a local landrace with an average PAA value of 11.77% and SPAA value of 1.21%/mg respectively, when ryegrass was used as the model weed. ‘Boset’ had the highest average PAA value of 16.25% and an SPAA value of 1.53%/mg, when using radish as the model weed. The lowest PAA and SPAA values were recorded from ‘DZ-Cr-3870 when using ryegrass and radish as model weeds. Days to emergence, height, tiller no./plant, biomass yield, and PAA of the crop significantly contributed to the variance of the weed biomass, cover, and density. Hence, they were the most important agronomic traits enhancing the competitive ability of teff.
Forfattere
Lars Olav Brandsæter Kjell Mangerud Lars Andersson Trond Børresen Guro Brodal Bo MelanderSammendrag
There is a need both in organic farming and on farms using integrated pest management for non-chemical measures that control the perennial weed flora. The effect of mechanical weeding and fertilisation on perennial weeds, fungal diseases and soil structure were evaluated in two different experiments in spring cereals. Experiment I included six strategies. The first strategy was (1) without specific measures against perennial weeds. The other strategies encompassed one or two seasonal control measures; (2) rhizome/root cutting with minimal soil disturbance in autumn, (3) hoeing with 24 cm row spacing, (4) combined hoeing and disc harrowing in autumn, (5) ‘KvikUp’ harrowing in spring, and (6) ‘KvikUp’ harrowing in spring and autumn. Experiment II included factor (i) inter-row hoeing and (ii) fertilisation level. This experiment included the comparison between normal row spacing (12 cm) with weed harrowing versus double row spacing (=24 cm) in combination with inter-row hoeing and 4 fertilisation levels (50–200 kg N ha−1). In experiment I the strategies consisting of no or one direct weed control measure (1, 2, 3 and 5) clearly did not control the perennial weeds. The two seasonal control measures (4 and 6) gave a satisfactory weed control and highest crop yield. The combination of best weed control and no measured harmful effects on soil structure or increase of fungal diseases may explain the highest yields for these strategies. In Experiment II, hoeing and 24 cm spacing gave less perennial biomass compared to 12 cm spacing. Grain yields increased linearly with increasing nitrogen input. The study shows that both inter-row hoeing and weed harrows, are important elements in integrated pest management practice and organic farming. In addition, our results indicate that efficient mechanical weeding is possible without harmful effects in crop rotation consisting of various spring cereals as regards soil structure and plant health.
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Haftamu Gebretsadik Gebrehiwot Jens Bernt Aune Jan Netland Ole Martin Eklo Torfinn Torp Lars Olav BrandsæterSammendrag
Teff is a staple and well adapted crop in Ethiopia. Weed competition and control have major effects on yields and economic returns of the crop in the country. Among the weed management methods, development and use of weed competitive teff varieties remain the cheapest and most sustainable weed management option. Ten teff varieties were tested for their weed competitive ability in two locations. Treatments were applied using a split plot design with three blocks at each location for two consecutive seasons. Hand weeding and non-weeded treatments were applied to whole plot treatments with teff varieties assigned as split plots within the whole plot. The main objective was to determine relative competitive ability among teff varieties. Results showed that teff varieties showed significant variation in their weed competitive abilities. The varieties ‘Kora’ and ‘DZ-Cr-387’ significantly reduced weed density, dry weight, and cover more than the other teff varieties. They also had the lowest yield losses with a loss of 6% in biomass yield and 18% in grain yield recorded from ‘Kora’ and a loss of 17% in biomass yield and 21% in grain yield recorded from ‘DZ-Cr-387’. Therefore, they showed the highest weed competitive ability compared to the other varieties.
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Denne rapporten gir en oversikt over fangvekster og deres effekter på avling, mineralsk nitrogen ijord, karbonbinding, utslipp til vann og luft, jordstruktur, biodiversitet og ugras. Det er fortrinnsvis brukt studier fra Norge og Norden for å øke kunnskapen om fangvekster....
Forfattere
Wiktoria Kaczmarek-Derda Marit Helgheim Jan Netland Hugh Riley Kjell Wærnhus Samson Øpstad Liv Østrem Lars Olav BrandsæterSammendrag
The abundance of Juncus effusus (soft rush) and Juncus conglomeratus (compact rush) has increased in coastal grasslands in Norway over recent decades, and their spread has coincided with increased precipitation in the region. Especially in water‐saturated, peaty soils, it appears from field observations that productive grasses cannot compete effectively with such rapidly growing rush plants. In autumn–winters of 2012–2013 and 2013–2014, a four‐factor, randomised block greenhouse experiment was performed to investigate the effect of different soil moisture regimes and organic matter contents on competition between these rush species and smooth meadow‐grass (Poa pratensis). The rush species were grown in monoculture and in competition with the meadow‐grass, using the equivalent of full and half the recommended seed rate for the latter. After about three months, above‐ and below‐ground dry matter was measured. J. effusus had more vigorous growth, producing on average 23–40% greater biomass in both fractions than J. conglomeratus. The competitive ability of both rush species declined with decreasing soil moisture; at the lowest levels of soil moisture, growth reductions were up to 93% in J. conglomeratus and 74% in J. effusus. Increasing water level in peat–sand mixture decreased competivitiveness of meadow‐grass, while pure peat, when moist, completely impeded its below‐ground development. These results show that control of rush plants through management may only be achieved if basic soil limitations have been resolved.
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Marie Reimer Björn Ringselle Göran Bergkvist Sally Westaway Raphaël Wittwer Jörg Peter Baresel Marcel G. A. van der Heijden Kjell Mangerud Maria R. Finckh Lars Olav BrandsæterSammendrag
Reducing soil tillage can lead to many benefits, but this practice often increases weed abundance and thus the need for herbicides, especially during the transition phase from inversion tillage to non-inversion tillage. We evaluated if subsidiary crops (SCs, e.g., cover crops) can mitigate the effects of non-inversion tillage on weed abundance. Two-year experiments studying SC use, tillage intensity, and nitrogen (N) fertilization level were carried out twice at six sites throughout northern and central Europe. SCs significantly reduced weed cover throughout the intercrop period (−55% to −1% depending on site), but only slightly during the main crops. Overall weed abundance and weed biomass were higher when using non-inversion tillage with SCs compared to inversion tillage without SCs. The effects differed due to site-specific weed pressure and management. With increasing weed pressure, the effect of SCs decreased, and the advantage of inversion over non-inversion tillage increased. N fertilization level did not affect weed abundance. The results suggest that SCs can contribute by controlling weeds but cannot fully compensate for reduced weed control of non-inversion tillage in the transition phase. Using non-inversion tillage together with SCs is primarily recommended in low weed pressure environments.
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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.
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Wiktoria Kaczmarek-Derda Anne-Kari Holm Lars Olav Brandsæter Knut Asbjørn Solhaug Inger Sundheim FløistadSammendrag
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Forfattere
Kirsten Tørresen Lars Olav Brandsæter Jan Netland Therese With Berge Björn Ringselle Einar StrandSammendrag
Glyfosat er det mest brukte plantevernmidlet i Norge og på verdensbasis. Det har i de siste årene vært diskutert om dette ugrasmiddelet skulle få fornyet godkjenning. I 2017 ble glyfosat godkjent for fem nye år til 2022. Dersom glyfosat fases ut er en redd det vil få store negative konsekvenser for jordbruk og matproduksjon. Glyfosat brukes til å bekjempe ugras og andre uønska planter på dyrka og udyrka arealer. I jordbruket er glyfosat spesielt viktig for å begrense ugrasets avlingsreduserende effekt. I norsk jordbruk brukes glyfosat hovedsakelig til å bekjempe ugrasarten kveke i korndominerte omløp og ved fornying av grasmark. Ved redusert jordarbeiding er glyfosat viktig for bekjemping av flerårige og andre overvintrende ugras. Vi har i denne rapporten kartlagt kunnskap relevante for norske forhold på hvilke ikke-kjemiske og kjemiske alternativer til glyfosat som en har/kan få i framtida i korn og grasmark slik at matproduksjonen kan opprettholdes. Mekaniske tiltak som pløying og ulike former for jordarbeiding i stubben mot kveke og andre ugras, og radrensing i korn mot ugras generelt er viktige alternativer til glyfosat. Det er også noen nye redskapstyper (rotskjærere) som virker lovende i bekjemping av ugras. Videre så vil en god jord- og plantekultur med et godt vekstskifte bidra til å holde ugraset under kontroll. Per i dag fins det noen få kjemiske alternativer mot kveke i hvete, rughvete og rug og mot tofrøblada rotugras i korn. Det er andre kjemiske alternativer som kan undersøkes mer for bruk i stubbåker/til brakking av grasmark som for eksempel ulike organiske syrer og grasugrasmidler for tofrøblada kulturer........
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Björn Ringselle Therese With Berge Daniel Stout Tor Arvid Breland Paul E. Hatcher Espen Haugland Matthias Koesling Kjell Mangerud Tor Lunnan Lars Olav BrandsæterSammendrag
Docks (Rumex spp.) are a considerable problem in grassland production worldwide. We investigated how different cultural management techniques affected dock populations during grassland renewal: (I) renewal time, (II) companion crop, (III) false seedbed, (IV) taproot cutting (V), plough skimmer and (VI) ploughing depth. Three factorial split-split plot experiments were carried out in Norway in 2007–2008 (three locations), 2008–2009 (one location) and 2009 (one location). After grassland renewal, more dock plants emerged from seeds than from roots. Summer renewal resulted in more dock seed and root plants than spring renewal. Adding a spring barley companion crop to the grassland crop often reduced dock density and biomass. A false seedbed resulted in 71% fewer dock seed plants following summer renewal, but tended to increase the number of dock plants after spring renewal. In some instances, taproot cutting resulted in less dock biomass, but the effect was weak and inconsistent, and if ploughing was shallow (16 cm) or omitted, it instead increased dock root plant emergence. Fewer root plants emerged after deep ploughing (24 cm) compared to shallow ploughing, and a plough skimmer tended to reduce the number further. We conclude that a competitive companion crop can assist in controlling both dock seed and root plants, but it is more important that the renewal time is favourable to the main crop. Taproot cutting in conjunction with ploughing is not an effective way to reduce dock root plants, but ploughing is more effective if it is deep and a skimmer is used.
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Increasing abundance of Juncus effusus (soft rush) and Juncus conglomeratus (compact rush) in pastures and meadows in western Norway has caused reductions in forage yield and quality in recent decades. Understanding plant development and regrowth following cutting is essential in devising cost-effective means to control rushes. In a field experiment in western Norway, we investigated development of above- and below-ground fractions of rush from seedlings to three-year-old plants, including the impact on vigour of disturbing growth by different cutting frequencies during the period 2009–2012. Each year, the plants were exposed to one or two annual cuts or left untreated and five destructive samplings were performed from March to early December. Juncus effusus showed significantly more vigorous growth than Juncus conglomeratus in the last two years of the study period. The above-ground:below-ground biomass ratio of both species increased mainly in spring and early summer and was reduced in late summer and autumn. Removal of aerial shoots also reduced the below-ground fraction of both species. One annual cut in July effectively reduced biomass production in both species by 30–82%, which was only a slightly smaller reduction than with two annual cuts, in June and August. Mechanical control measures such as cutting can thus effectively reduce rush vigour when performed late in the growing season.
Forfattere
Björn Ringselle Erik Bertholtz Ewa Magnuski Lars Olav Brandsæter Kjell Mangerud Göran BergkvistSammendrag
Tillage controls perennial weeds, such as Elymus repens, partly because it fragments their underground storage organs. However, tillage is difficult to combine with a growing crop, which limits its application. The aim of this study was to evaluate how soil vertical cutting with minimum soil disturbance and mowing affect the growth and competitive ability of E. repens in a grass–clover crop. A tractor-drawn prototype with vertical disks was used to fragment E. repens rhizomes with minimal soil and crop disturbance. In experiments performed in 2014 and 2015 at a field site close to Uppsala, Sweden, the rhizomes were fragmented before crop sowing (ERF), during crop growth (LRF), or both (ERFCLRF). Fragmentation was combined with repeated mowing (yes/no) and four companion crop treatments (none, Italian ryegrass, white clover, and grass/clover mixture). The results showed that in the grass–clover crop, rhizome fragmentation reduced E. repens rhizome biomass production and increased Italian ryegrass shoot biomass. ERF and LRF both reduced E. repens rhizome biomass by about 38% compared with the control, while ERFCLRF reduced it by 63%. Italian ryegrass shoot biomass was increased by 78% by ERF, 170% by LRF and 200% by ERFCLRF. Repeated mowing throughout the experiment reduced E. repens rhizome biomass by about 75%. Combining repeated mowing with rhizome fragmentation did not significantly increase the control effect compared to mowing alone. We concluded that rhizome fragmentation using vertical disks can be used both before sowing and during crop growth to enhance the controlling effect of grass–clover crops on E. repens.
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Control of perennial weeds, such as Elymus repens, generally requires herbicides or intensive tillage. Alternative methods, such as mowing and competition from subsidiary crops, provide less efficient control. Fragmenting the rhizomes, with minimal soil disturbance and damage to the main crop, could potentially increase the efficacy and consistency of such control methods. This study's aim was to investigate whether fragmenting the rhizomes and mowing enhance the control of E. repens in a white clover sward. Six field experiments were conducted in 2012 and 2013 in Uppsala, Sweden, and Ås, Norway. The effect of cutting slits in the soil using a flat spade in a 10 × 10 cm or 20 × 20 cm grid and the effect of repeated mowing were investigated. Treatments were performed either during summer in a spring-sown white clover sward (three experiments) or during autumn, post-cereal harvest, in an under-sown white clover sward (three experiments). When performed in autumn, rhizome fragmentation and mowing reduced E. repens shoot biomass, but not rhizome biomass or shoot number. In contrast, when performed in early summer, rhizome fragmentation also reduced the E. repens rhizome biomass by up to 60%, and repeated mowing reduced it by up to 95%. The combination of the two factors appeared to be additive. Seasonal differences in treatment effects may be due to rhizomes having fewer stored resources in spring than in early autumn. We conclude that rhizome fragmentation in a growing white clover sward could reduce the amount of E. repens rhizomes and that repeated mowing is an effective control method, but that great seasonal variation exists.
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Creeping perennial weeds are of major concern in organically grown cereals. In the present study, the effects of different timing of mouldboard ploughing with or without a preceding stubble cultivation period, on weeds and spring cereals were studied. The experiments were conducted at two sites in Norway during a two and three-year period, respectively, with the treatments repeated on the same plots. The soil cultivation treatments were a stubble disc-harrowing cultivation period followed by mouldboard ploughing and only mouldboard ploughing. The timing of the treatments were autumn or spring. The density and biomass of the aboveground shoots of Cirsium arvense (L.) Scop., Elymus repens (L.) Gould, Sonchus arvensis L. and Stachys palustris L. as well as the total aboveground biomass of the spring cereal crop (oats) were assessed. The control efficiency of C. arvense and S. arvensis was closely related to timing of the cultivation treatments. Cultivation in spring decreased the population of C. arvense and S. arvensis compared to autumn cultivation. For E. repens, timing of the treatments had no significant effect: the important factor was whether stubble cultivation was carried out (best control) or not. The overall best strategy for controlling the present perennial weed population was stubble cultivation followed by ploughing in spring. However, the associated relative late sowing of the spring cereal crop and lowered crop biomass, were important drawbacks.
Forfattere
Dorothee Kolberg Lars Olav Brandsæter Göran Bergkvist Knut Asbjørn Solhaug Bo Melander Björn RingselleSammendrag
Quackgrass is a problematic agricultural weed in the temperate zones of the world and is difficult to control without herbicides or intensive tillage. However, it may be possible to control quackgrass with less environmental impact by combining multiple low-intensity control methods. A pot experiment was conducted in July to October 2012 and repeated in June to September 2013 to investigate the effect of rhizome fragmentation, competition from white clover, shoot-cutting frequency, and cutting height on quackgrass. Rhizome fragmentation was expected to result in more, but weaker, quackgrass shoots that would be more vulnerable to shoot cutting and competition. However, by 20 d past planting, rhizome fragmentation did not change the total number of quackgrass shoots per pot, because an increase in main shoots was offset by a decrease in tiller numbers. Rhizome fragmentation did not reduce quackgrass biomass acquisition during the experimental period. Although rhizome fragmentation did reduce total fructan content, it did not enhance the effect of clover competition, shoot-cutting frequency, or shoot-cutting height. Clover competition by itself reduced quackgrass shoot numbers by 72%, rhizome biomass by 81%, and belowground fructan concentration by 10 percentage points, compared with no competition. The more frequently quackgrass shoots were cut, the less biomass quackgrass acquired, and a high shoot-cutting frequency (each time quackgrass reached 2 leaves) resulted in a lower belowground fructan concentration than a low shoot-cutting frequency (at 8 leaves). However, in pots without competition, a higher shoot-cutting frequency resulted in more quackgrass shoots. A lower shoot-cutting height (25 mm) had more impact when shoot cutting was more frequent. In conclusion, rhizome fragmentation did not reduce the number of quackgrass shoots or rhizome biomass, but competition from white clover, a high shoot-cutting frequency, and a low shoot-cutting height strongly suppressed quackgrass biomass and fructan acquisition.
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During the past two decades, significant spread of the perennial weeds Juncus effusus (soft rush) and Juncus conglomeratus (compact rush) in coastal parts of Norway seems to have coincided with an observed rise in winter temperatures. This study investigated the frost tolerance (LT50) and effects of moderate frost exposure on rush plant regrowth over time during the period late November to late winter/spring, and photosynthetic activity in late winter/spring. Juncus effusus and J. conglomeratus of physiologically young age (seedlings) displayed similar high frost tolerance (LT50) and did not differ significantly in regenerative ability following prolonged frost exposure. Regrowth capacity generally increased during winter and when stress conditions increased, shoot formation was prioritised over total biomass production. Maximum quantum efficiency of photosystem II (Fv/Fm) and performance index of photosystem II (PI) were high in late winter/spring, with J. effusus showing higher values than J. conglomeratus. Green, photosynthetically active shoots, which facilitate accumulation of carbohydrates during autumn and even in winter, may provide Juncus spp. with substantial competitiveness in late winter and spring. The results revealed that the dominance of J. effusus over J. conglomeratus in pastures and leys is not due to major differences in winter survival parameters, but probably the higher photosynthetic efficiency observed in J. effusus. Generally higher temperatures during winter and lower frost kill may be contributing to the current increase in rush infestation.
Forfattere
Anne-Kari Holm Abdelhameed Elameen Benedikte Watne Oliver Lars Olav Brandsæter Inger Sundheim Fløistad May Bente BrurbergSammendrag
Knowledge about the reproduction strategies of invasive species is fundamental for effective control. The invasive Fallopia taxa (Japanese knotweed s.l.) reproduce mainly clonally in Europe, and preventing spread of vegetative fragments is the most important control measure. However, high levels of genetic variation within the hybrid F. × bohemica indicate that hybridization and seed dispersal could be important. In Norway in northern Europe, it is assumed that these taxa do not reproduce sexually due to low temperatures in the autumn when the plants are flowering. The main objective of this study was to examine the genetic variation of invasive Fallopia taxa in selected areas in Norway in order to evaluate whether the taxa may reproduce by seeds in their most northerly distribution range in Europe. Fallopia stands from different localities in Norway were analyzed with respect to prevalence of taxa, and genetic variation within and between taxa was studied using amplified fragment length polymorphism (AFLP). Taxonomic identification based on morphology corresponded with identification based on simple sequence repeats (SSR) and DNA ploidy levels (8× F. japonica, 6× F. × bohemica and 4× F. sachalinensis). No genetic variation within F. japonica was detected. All F. × bohemica samples belonged to a single AFLP genotype, but one sample had a different SSR genotype. Two SSR genotypes of F. sachalinensis were also detected. Extremely low genetic variation within the invasive Fallopia taxa indicates that these taxa do not reproduce sexually in the region, suggesting that control efforts can be focused on preventing clonal spread. Climate warming may increase sexual reproduction of invasive Fallopia taxa in northern regions. The hermaphrodite F. × bohemica is a potential pollen source for the male-sterile parental species. Targeted eradication of the hybrid can therefore reduce the risk of increased sexual reproduction under future warmer climate.
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Lars Olav BrandsæterSammendrag
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Anne-Kari Holm Abdelhameed Elameen Benedikte Watne Oliver May Bente Brurberg Inger Sundheim Fløistad Lars Olav BrandsæterSammendrag
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Wiktoria Kaczmarek-Derda Lars Olav Brandsæter Knut Asbjørn Solhaug Liv Østrem Arve Arstein Håkon Pedersen Jan NetlandSammendrag
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Anne-Kari Holm Inger Sundheim Fløistad Knut Asbjørn Solhaug Benedikte Watne Oliver Lars Olav BrandsæterSammendrag
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Vitenskapelig – Forstå skræppernes biologi og lav den rette bekæmpningsstrategi
Lars Olav Brandsæter
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Anne-Kari Holm Abdelhameed Elameen Benedikte Watne Oliver May Bente Brurberg Inger Sundheim Fløistad Helge Sjursen Lars Olav BrandsæterSammendrag
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Anne-Kari Holm Abdelhameed Elameen Benedikte Watne Oliver May Bente Brurberg Inger Sundheim Fløistad Helge Sjursen Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Leif Sundheim Trond Hofsvang Christer Magnusson Gunnar Sundstøl Eriksen Lars Olav Brandsæter Guro Brodal Siv Fagertun Remberg Anne Kjersti Uhlen Åshild Kristine Andreassen Augustine Arukwe Aksel Bernhoft Knut Egil Bøe Margaretha Haugen Gro Ingunn Hemre Åshild Krogdahl Torsten Källqvist Jørgen Fredrik Lassen Bjørn Næss Trond Rafoss Janneche Utne Skåre Arild Sletten Halvor Solheim Inger-Lise Steffensen Ole Torrissen Anne Marte Tronsmo Bjørn Økland Jan AlexanderSammendrag
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Lars Olav BrandsæterSammendrag
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Wiktoria Kaczmarek-Derda Johannes Andre Folkestad Marit Helgheim Jan Netland Knut Asbjørn Solhaug Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Wiktoria Kaczmarek-Derda Lars Olav Brandsæter Knut Asbjørn Solhaug Liv Østrem Arve Arstein Håkon Pedersen Jan NetlandSammendrag
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Wiktoria Kaczmarek-Derda Lars Olav Brandsæter Knut Asbjørn Solhaug Liv Østrem Arve Arstein Håkon Pedersen Jan NetlandSammendrag
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Kirsten Tørresen Ingerd Skow Hofgaard Ole Martin Eklo Jan Netland Lars Olav Brandsæter Guro Brodal Oleif Elen Andrea Ficke Marit Almvik Randi Bolli Marianne Stenrød Einar StrandSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Kirsten Tørresen Ingerd Skow Hofgaard Jan Netland Lars Olav Brandsæter Guro Brodal Oleif Elen Andrea Ficke Marit Almvik Randi Bolli Marianne Stenrød Einar StrandSammendrag
Plogen har tradisjonelt vært viktig for å få et godt såbed, for innblanding av halmrester og gjødsel i jorda, og for god bekjemping av ugras og sjukdommer. Redusert jordarbeiding uten bruk av plogen, gir imidlertid store miljøfordeler i form av mindre erosjon og utvasking av næringsstoffer. Denne rapporten fokuserer på konsekvenser av ulik jordarbeiding på plantevernsituasjonen i korn. Basert på dagens kunnskap fra norske og internasjonale studier konkluderes det med at redusert jordarbeiding gir økt risiko for utvikling av ugras og plantesjukdommer, samt mykotoksiner. I tillegg kan redusert jordarbeiding føre til økt bruk av kjemiske plantevernmidler som glyfosat, fenoksysyrer og soppmidler. Ugraset og de fleste plantesjukdommer kan som regel bekjempes med plantevernmidler, mens Fusarium spp. og mykotoksiner bare delvis kan bekjempes av kjemiske midler. Miljørisikoen av kjemiske plantevernmidler påvirkes av egenskaper til plantevernmidlene. Redusert jordarbeiding fører til økt risiko for transport til grunnvann av fenoksysyrer og lavdosemidler (sulfonylurea-preparater). Risiko for transport til overflatevann av ugrasmidler og soppmidler er minst når åkeren ligger i stubb. Været og klimaet har stor betydning for utvikling av skadegjørerne, risiko for utvikling av mykotoksiner og utvasking av plantevernmidler. Vårpløying kan være gunstig miljømessig sett fordi det kan redusere erosjon og næringsstofftap. Samtidig gir det mindre behov for, og derfor redusert miljørisiko av, plantevernmidler enn andre typer jordarbeiding. Vårpløying egner seg derimot dårlig på stiv leirjord, det fører til større tidspress på våren og risiko for forsinka våronn og derved lavere avling.
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav BrandsæterSammendrag
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Lars Olav Brandsæter Anne Kjersti Bakken Kjell Mangerud Hugh Riley Ragnar Eltun Haldor FykseSammendrag
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Kirsten Tørresen Jan Netland Lars Olav Brandsæter Ingerd Skow Hofgaard Oleif Elen Andrea Ficke Guro Brodal Ole Martin Eklo Marit Almvik Randi Bolli Marianne Stenrød Einar StrandSammendrag
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Lars Olav Brandsæter Kirsten Tørresen Therese With Berge Aina Lundon Russenes Kjell MangerudSammendrag
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Docks are among the most important perennial weeds in grasslands throughout the world and the need for more effective control methods is especially crucial in organic forage production. To find more effective control methods, field trials over 2 years at 4 Norwegian locations, were carried out mainly as a full-factorial design, including factors expected to reduce docks significantly. (i) Date of grassland establishment: may be important for preventing/decreasing the flush of seedlings from seeds as well as shoots from root fragments.(ii) False seedbed preparation: to decrease soil seed bank. (iii) Use of nurse crop (cover crop) to increase competitiveness against Rumex seedlings. (iv) Cutting the taproot, using a rotary tiller before ploughing, or the "dock-plough" (a skimmer modified to cut roots in the entire furrow width at ca 7 cm depth): as new shoots mostly come from the neck and the upper 5 cm of the taproot. (v) Ploughing depth and skimming: to decrease shoots from root fragments. Weed development was assessed as the number of emerging Rumex seedlings and plants sprouting from root fragments. Results indicated that frequently more plants emerged from seeds than from root fragments. Neither renewing the grassland in summer, nor the use of the rotary tiller or the "dock plough" reduced the number of docks in the renewed grasslands. The use of the false seedbed and nurse crop, at some locations and years, reduced the number of docks in the renewed grasslands. Deep ploughing (24cm) reduced the number of Rumex plants from roots by 65% percent compared to shallow ploughing (16cm). Furthermore, the use of a skimmer reduced the number of docks sprouting from roots by 28%. Among the investigated factors, competitiveness, false seedbed and ploughing depth, as well as ploughing quality, seems to be the most promising factors for reducing the number of docks in renewed grassland.
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Lars Olav Brandsæter H Fogelfors Haldor Fykse E Graglia RK Jensen Bo Melander J Salonen P VanhalaSammendrag
The success of weed management aimed at depleting the regenerative structures of perennial weeds depends largely on the sprouting activity of rhizome and root buds. Seasonal variation in sprouting of these buds on Cirsium arvense, Sonchus arvensis and Elymus repens was studied for plants collected from Denmark, Finland, Norway and Sweden. At 2-week intervals from July to October, 5-cm fragments of roots or rhizomes were cut from plants grown in buckets and planted into soil in pots, half of which were placed immediately into growth chambers at 18 degrees C for 4 weeks. The other half of the pots were initially placed in a dark room at 2 degrees C for 4 weeks before being transferred to the same growth chamber, also for 4 weeks. During the growth chamber period, the numbers of emerged shoots in each pot were counted weekly. The sprouting activity of C. arvense and E. repens was relatively uniform during this period and bud dormancy was not apparent. In all ecotypes of S. arvensis, innate bud dormancy developed during the latter part of the growing season. For all three species, differences in sprouting readiness were found among ecotypes. The results imply that C. arvense and E. repens are more likely to be controlled by mechanical measures in autumn than S. arvensis.
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Control of dock species are a true bottleneck in the development of grassland based organic forage production in Norway. Rumex obtusifolius, Rumex crispus and Rumex longifolius are among the most important perennial weeds in grassland areas throughout the world. These dock- species are undesired in grasslands because they decrease yields and reduce forage feeding value. The experiment in our study is carried out as a full-factorial design, including key-factors, which may influence dock behaviour significantly. The first factor, (i) date of grassland establishment, may be important for preventing /decreasing the flush of seedlings from seeds as well as shoots from root fragments. The purpose of the second factor, (ii) black fallow, is both false seedbed preparation and decreasing food reserves in underground plant parts. The third factor, (iii) is the use of equipment for cutting the taproot either (a) before ploughing by using a tractor propelled rotovator, or (b) cutting the dock taproot in the same operation as ploughing by using a prototype ¿two layer dockplough¿. The biological background for cutting the taproot before ploughing is that many studies have shown that new shoots only come from the 5 upper cm of the taproot. Furthermore, our hypothesis is that shoots from highly fragmented regenerative parts (the neck) of the taproot placed deep will not reach the soil surface before their reserves are depleted. Experiments were carried out at 3 and 4 locations in 2007 and 2008, respectively. Weed development were assessed as number of emerging seedlings as well as number of sprouting plants from root fragments, both in the year when the treatments were carried out and the following year. The results are yet not completely analyzed, but preliminary results indicate that plants from seeds frequently are more numerous than plants from roots. At least at some locations and years both the use of rotovator and the ¿dock plough¿, has reduced the number of plants from root fragments with approx. 50%. However, our experiments have shown that ¿dock plough¿ prototype has to be improved, especially because it did not cut the taproot near the open furrow, and did not bury the green parts well enough.
Forfattere
Anne Kjersti Bakken Lars Olav Brandsæter Ragnar Eltun Sissel Hansen Kjell Mangerud Reidun Pommeresche Hugh RileySammendrag
The relative effects of using light (2-3 Mg) versus heavier (5-7 Mg) tractors, shallow (15 cm) versus deeper (25 cm) ploughing and on-land versus in-furrow wheel placement during ploughing were investigated from 2003 to 2006 in organic rotations (wheat or barley, green manure, oats with peas) and conventionally fertilized barley. Trials were located on loam soil in south-eastern Norway and silty clay loam in central Norway. Ploughing was performed in spring, when the topsoil moisture content was at or below field capacity, using single furrow ploughs that allowed alternative wheel placement and resulted in complete coverage of the surface by wheels each year (ca. 3 times the normal coverage during ploughing). Low tyre inflation pressures (:<= 80 kPa) were used throughout. The use of a heavy tractor increased topsoil bulk density slightly in the loam soil, and, in combination with in-furrow wheeling, it reduced air-filled pore space and air permeability at 18-22 cm. On the silty clay loam, the use of a heavy tractor did not increase bulk density, but it reduced air-filled pore space throughout the topsoil. In-furrow wheeling reduced air-filled pore space in this soil also, compared to on-land wheeling. Penetration resistance was in this soil always greater at 15-25 cm depth after shallow than after deep ploughing, especially with in-furrow rather than on-land wheeling. Shallow ploughing led on both soils to marked increases in perennial weed biomass compared to deep ploughing. Earthworms were hardly affected by the treatments, but in the loam in 2006 a higher number of individuals were found where the light rather than the heavy tractor had been used. Few significant treatment effects were found on grain yield and quality. Deep ploughing with a light tractor gave the highest wheat yield and protein content in 2 years on the loam soil, and on the silty clay loam the yield of conventionally fertilized barley was higher after deep than after shallow ploughing. In summary, limited evidence was found to support the use of on-land rather than in-furrow wheeling when ploughing is performed at favourable soil moisture and with tractor weights < 5 Mg. There is, however, reason to be wary of using heavy tractors (> 5 Mg), even under such conditions. With regard to ploughing depth in organic rotations dominated by cereals, the need to combat perennial weeds by deep ploughing weighs probably more heavily than any possible beneficial effect of shallow ploughing on stimulating nutrient turnover. (C) 2008 Elsevier B.V. All rights reserved.
Forfattere
Lars Olav BrandsæterSammendrag
Gjennom flere år har vi utført forsøk som belyser effekten av pløyedybde om våren på ulike rotugrasarter. I en annen forsøkssøkserie fokuserer vi på tidspunkt, høst vs. vår, for jordarbeiding/brakking, også i forhold til effekten på ulike ugrasarter.
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Hugh Riley Anne Kjersti Bakken Lars Olav Brandsæter Ragnar Eltun Sissel Hansen Kjell Mangerud Reidun PommerescheSammendrag
Effekter av traktorvekt, pløyedybde og kjøremåte under pløying ble undersøkt på to jordarter i et økologisk vekstskifte. Forsøksbehandlingene hadde relativt liten effekt på avling (sv. skörd), men djup pløying var ofte best bl.a. fordi det reduserte mengden rotugras. Både pløying med hjulene i fåra og bruk av tyngre traktorer hadde uheldige (sv. olyckliga) virkninger på jordstrukturen. Dekkdimensjoner,hjulbelastning og dekktrykk bør kombineres på en slik måte at jordpakking unngåsi dypere jordlag.
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Ingeborg Klingen Trond Hofsvang Lars Olav Brandsæter Solveig Haukeland Espen Haugland Nina JohansenSammendrag
I denne artikkelen beskriver vi alternativ bekjempelse og fascinerende prosesser som er med på å redusere problemene med skadeorganismer (skadedyr, sykdomsorganismer og ugras). I dette inkluderer vi både naturlige fiender, luktstoffer og overvintring.
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En gjennomgang av de viktigste skadeorganismer (skadedyr, sjukdommer og ugras) som forekommer i grønnsaker og potet i Norge, samt bekjempingsmetoder som er tillatt og anbefalt ved økologisk dyrking.
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Hugh Riley Anne Kjersti Bakken Lars Olav Brandsæter Ragnar Eltun Sissel Hansen Kjell Mangerud Reidun PommerescheSammendrag
Effekter av traktorvekt, pløyedybde og kjøremåte under pløying ble undersøkt på to jordarter i et økologisk vekstskifte. Forsøksbehandlingene hadde relativt liten effekt på avling, men djup pløying var ofte best bl.a. fordi det reduserte mengden rotugras. Både pløying med hjulene i fåra og bruk av tyngre traktorer hadde uheldige virkninger på jordstrukturen. Dekkdimensjoner, hjulbelastning og dekktrykk bør kombineres på en slik måte at jordpakking unngås i dypere jordlag. En metode for å vurdere dette ble nylig lansert på internett i Danmark.
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Ugrasharving før kornets oppspiring eller på kornets 1-bladstadium vil i de aller fleste tilfellene redusere ugrasmengden. Ytterligere reduksjon får en ved å harve på nytt ved 3-4 bladstadiet. Som oftest vil harving rundt kornets oppspiring gi avlingsøkning sammenlignet med ubehandlet. Ny harving på 3-4-bladstadiet kan gi avlingsøkning, avhengig av ugrasmengden.
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Helge Sjursen Lars Olav Brandsæter Anne-Kristin Løes Trond Henriksen Mette Thomsen Ragnar EltunSammendrag
Tradisjonelt er grønngjødslingseffekten den viktigste årsaken til å benytte kløver underkultur i korn. I flere omfattende forsøk har vi imidlertid nå studert hvordan bruk av underkultur i korn påvirker veksten til både ett- og flerårig ugras.
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Rotugras skaper ofte problemer i økologiske omløp dominert av korn. I de beskrevne forsøkene har vi sett på ulike metoder for bekjemping av åkertistel (Cirsium arvense) og andre rotugras i ettårig grønngjødslingseng. Mest fokus har vi gjort på kombinasjonen vårbrakking før såing av grønngjødslingsvekst.
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Det er gjennomført en spørreundersøkelse blant bønder som viser at forsøksopplegget i programmet "Økologiske dyrkingssytemer for større og mer stabile kornavlinger" er relevant med hensyn til den pløyedybde, traktorstørrelse og det dekktrykk som brukes i praktisk økologisk korndyrking i Norge i dag. Det er samsvar mellom enkelte av de foreløpige forsøksresultatene og de tendensene en kan se fra svarene fra spørreundersøkelsen. Undersøkelsen viser at det er store variasjoner i avlingene ute hos praktikerne. Bøndene er opptatt av jordarbeiding og pakkeskader, og derfor vil resultatene en til slutt kommer fram til i forsøkene være til nytte for praktisk drift, også dersom det viser seg at utslaget for en eller flere av faktorene er lite.
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Innenfor det strategiske instituttprogrammet "Økologiske dyrkingssystemer for større og mer stabile kornavlinger" er det høsten 2005 foretatt en intervjuundersøkelse av 24 bønder. Resultatet av disse intervjuene er presentert og evaluert opp mot behandlingene og foreløpige resultater i programmet.
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Kostnadene i forbindelse med ikke-kjemiske ugrastiltak i grønnsaker kan være store, noe som derfor kobler ugraskontroll nært opp til verdikjede og markedsrelaterte problemstillinger. Dette innlegget gir en oversikt over hvilke typer utstyr som er tilgjengelig på markedet i dag, samt et lite innsyn i utvikling av nye redskapstyper.
Populærvitenskapelig – Ny omfattende håndbok om plantevern i økologisk landbruk
Lars Olav Brandsæter
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Lars Olav BrandsæterSammendrag
I et omfattende formidlingsprosjekt har vi laget 4 bøker om plantevern og plantehelse i økologisk landbruk. Det første bindet er av generell karakter og omhandler i tillegg til stoff om bakgrunnen for økologisk landbruk og plantevern i denne produksjonsformen, kapittel om de ulike skadegjøreres biologi og aktuelle forbyggende og direkte tiltak. De 3 andre bindene er mer anvendte i sin karakter og er vinklet mer mot praktiske dyrkingsråd for kontroll av skadegjørere i de utvalgte kulturene.
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Kjell Mangerud Lars Olav Brandsæter Svein Magne Birkenes Birgitte Henriksen Richard Meadow Theo Ruissen Reidar Holmøy Helge Sjursen Guro BarstadSammendrag
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Ragnar Eltun G. Guttormsen Erling Stubhaug Hugh Riley Lars Olav Brandsæter Richard Meadow Trond M. Henriksen A.K. Løes Anne Kjersti Bakken Åsmund Asdal Trygve S. Aamlid T.A. Breland Trond K. Haraldsen Tore Sveistrup J. Olsen A-C. Wallenhammar A. NykanenSammendrag
Publikasjonen inneheld samandragsartiklar frå avsluttingsseminaret for det stratgiske instituttprogrammet "Næringsforsyning i økologiske dyrkingssystem med lite husdyrgjødsel". Følgjande emne er presentert:1) Gjødslingsvekster som nitrogenkilde ved dyrking av grønnsaker, 2) Oppsummering av erfaringene med bruk av underkulturer og med bruk av planteavklipp som dekkemateriale ved grønnsakdyrking på Kise 1998-2002, 3) Helhetlige metoder for kontroll av ugras og skadedyr i radkulturer ved hjelp av underkultur og plantavklipp, 4) Forgrøder og organiske gjødselslag som næringskilde til korn, 5) Ettervirkning av frøeng i økologiske omløp, 6) Fosfor- og kaliumeffektivitet i bygg og vårhvete: Forskjeller mellom eldre og nyere sorter, 7) Avlingar og jordeigenskapar gjennom seks års økologisk drift i dyrkingssystema på Planteforsk Landvik, Østre Voll, NLH og Planteforsk Kvithamar, 8) Forsøk med økologisk plantedyrking uten husdyr i Danmark, 9) Kvalitetsdyrking av økologisk vårhvete etter kløverrik eng i Sverige, 10) Finske forsøk med næringsforsyning i økologiske dyringssystem med lite eller ingen tilførsel av husdyrgjødsel.
