Biology of perennial weeds, prevention, control and management in organic crop rotations

Rasmussen, Ilse A.

English

Organic Eprints

Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Perennial weedsin a crop rotation perspectiveIlse A. RasmussenDept. of Integrated Crop ProtectionDanish Institute of Agricultural SciencesResearch Centre Flakkebjerg20 cm60 cm40 cmTussilago farfara Sonchus arvensis Elymus repensFrom Korsmo et al. 198150 cm100 cmCirsium arvense Equisetum arvenseFrom Korsmo et al. 1981Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006I II III IV VI: Initial growthII: Emergence of first shootIII: Dry weight minimum of the whole plantIV: Dry weight minimum of subterranian partsV: Dry weight of subterranian parts larger than at I1: Original vegetative propagation organs2: New vegetative propagation organs3: New shoots under ground 4: Shoots above groundModified after Håkansson 2003Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006I II III IV VElymus repensIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006I II III IV VTussilago farfaraIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006I II III IV VCirsium arvenseIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Traditional E. repens controlIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Integrated approach Crop, grainSuppressivecatch cropAutumn ploughing(20 cm) Strategy I: ”Integrated light” Early August, mechanical disintegrationFrom Melander et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Shallow ploughingRoterendeTine stubble cultivationP.t.o.-driven rotary cultivationMechanical disintegrationThe ’Kvik-Up’ harrowIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Strategy I: ”Integrated light” E. repensbiomass (g m-2) aabcd020406080100120140Untreated Shal. Pl. Rot. cul. Stub. cul. Kvik-UpEffects recorded close to spring barley harvest the following year From Melander et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Strategy I: ”Integrated light” 33.544.555.560 50 100 150 200No catch crop Radish/ryegr. Cl./vetchE. repens biomass (g m-2)Grain yield (t ha-1)From Melander et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Integrated approach Silage cropSuppressive catch crop1’st July, shallow ploughing (10 cm)Following season, ploughing (20 cm) prior to next cropEarly August, ploughing (20 cm)Strategy II: ”Integrated intensive”Fallow, tine cultivationFrom Melander et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Long fallow period Silage Crop1’st July, shallow ploughingStrategy III: ”Half fallow”Fallow, tine cultivationAutumn ploughing (20 cm) From Melander et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006TraditionalCrop, grainAutumn ploughing (20 cm) Early August, onsetof post-harvest cultivationStrategy IV: ”Traditional strategy” Post-harvest tine cultivationFrom Melander et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Results from 4 experiments IntegratedintensiveHalf fallow TraditionalNovember July  June 050100150200250E. repensshootsm-2From Melander et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Results from 4 experiments ab b00,511,522,533,544,55Grain yield (t ha-1)IntegratedintensiveHalf fallow TraditionalSpring barley grain yield the following yearFrom Melander et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Repeated hoeing in spring barley with undersown cloverYear one: treatmentsHoeing in crop May - JulySuppressivecatch cropAutumn ploughing(20 cm) Crop: spring barley. Year two: counts/weights + yieldFrom Graglia et al. 2004Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Hoeing: mid-May – mid-JulyRepeated hoeingNumber of hoeings0123456Aboveground biomass (g/m2)0102030405060Harvest 2002Harvest 2003From Graglia et al. 2004Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Repeated hoeingHoeing: medio May-medio JulyNumber of hoeings0135Yield (100 kg/ha)01020304050 Harvest 2002Harvest 2003From Graglia et al. 2004Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Repeated mowing in clover or without cropCrop: spring barley. Year three: counts/weights + yieldYear one: establishmentCrop: spring barley Suppressivecatch crop No catch cropMowing in clover/weeds May - July Suppressivecatch cropAutumn ploughing(20 cm) Year two: treatmentsNo catchcropFrom Graglia et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Before AfterMowing weeds without cloverIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Before AfterMowing cloverIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Number of mowings01234567Aboveground biomass (g/m2)050100150200250300350 With out catch cropWith catch cropRepeated mowingHarvest 2002Mowing: mid-May - late JulyFrom Graglia et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Number of mowings0246Yield (100kg/ha)0102030405060 With out catch crop   XWith catch crop          YRepeated mowingHarvest 2002Mowing: mid-May - late Julyabab abFrom Graglia et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Number of mowings01234567Aboveground biomass (g/m2)020406080100With out catch cropWith catch cropRepeated mowingHarvest 2003Mowing: mid-May - late JulyFrom Graglia et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Number of mowings0246Yield (100kg/ha)0102030405060 With out catch crop   XWith catch crop          YRepeated mowingHarvest 2003Mowing: mid-May - late JulyFrom Graglia et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Experimental factors• Crop rotation (level of cereals)• Catch crop (without/with catch crop)• Manure (without/with)Organic crop rotation experimentsIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Crop rotationsFour-year crop rotations are used.The level of cereals and pulsesincreases from rotation 1  to rotation 4:1: 1.5 grass-clover + 1 pulse2: 1 grass-clover + 1 pulse3: 1 grass-clover4: 1 pulseIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Weed control - perennials• Elymus repens :– stubble cultivation:• without catch crops > 5 shoots m-2• with catch crops - none– cutting the grass-clover more often at more than 5 shoots m-2 in the preceding cropIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Weed control - perennials• Elymus repens :– Rotations with and without catch crops with severe problems:• Grass clover plowed early (June)• Repeated harrowing• Competitive catch crop sown after 6-8 weeks• ”Summer fallow”Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Weed control - perennials• Cirsium arvense:– cut below ground and pulled at the anthesis of the cereals– stubble cultivation• Others (Artemisia vulgaris, Rumex crispus etc.):– pulled up at sight• Stubble cultivation in systems without catch cropsIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Catch cropsIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Nitrate leaching with or without catch crop in rotation with grass-cloverLeaching of nitrate-N (kg/ha/year)020406080100120Without catch cropWith catch cropCoarsesandLoamysandSandyloamFrom Rasmussen et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Control of perennial weeds in stubbleIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006N-leaching on coarse sandy soil with or without catch crops and stubble cultivationPulses CerealsLeaching of nitrate-N kg ha-1020406080100120140 +CC -CC - Stubble cult. -CC + Stubble cult. From Rasmussen et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006 1997 1998 1999 2000 2001 2002 2003E. repens shoots m-2020406080- CC + Stubble cult.+ CC - Stubble cult.E. repens shoots in spring barley on coarse sandy soil with and without catch cropsFrom Rasmussen et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006 Winter wheat Pulses Spring cerealsFresh weight of C. arvense (g m-2)0102030405060-CC + Stubble cult. +CC - Stubble cult. C. arvense biomass on sandy loam in different crop types with and without catch cropsFrom Rasmussen et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Summary• Catch crops should be included in systems with grass-clover to reduce nitrate leaching when possible, especially on sandy soils– but use of catch crops precludes stubble cultivation• Stubble cultivation should be used to reduce E. repens infestations– but not after pulses• Stubble cultivation did not seem to reduce C. arvensebiomass in our experimentsIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Control of perennial weeds in grass-clover: Summer fallowIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 20061997 1998 1999 2000 2001 2002 2003Concentration af nitrate-N (mg/l)01020304050No summer fallow Summer fallowConcentrations of nitrate-N on coarse sandy soil. Mean of 4 crops, without catch crop, with manureFrom Rasmussen et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006First crop Second cropE. repens shoots m-20510152025No fallow Fallow after grass-cloverE. repens shoots on coarse sandy soilafter grass-clover with or without summer fallow1997 1998 1999 2000 2001 2002 2003E. repens shoots m-2020406080- CC + Stubble cult.+ CC - Stubble cult.From Rasmussen et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Summary• Summer fallow could be used to reduce E. repens infestations– mainly the first year after fallow– increases risk of nitrate leaching on sandy soil• Other options should be preferredIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Nitrate leaching with or without catch cropin rotations with or without grass-cloverLeaching of nitrate-N (kg/ha/year)0102030405060Without catch cropWith catch cropLoamysandSandyloamLoamysandSandyloamWith grass-clover Without grass-cloverFrom Rasmussen et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006 Winter wheat Pulses Spring cerealsFresh weight of C. arvense, g m-20204060With grass-cloverWithout grass-cloverC. arvense biomass on sandy loamin different crop types in two rotationsFrom Rasmussen et al. 2005Ilse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Summary• Grass-clover can be managed to reduce C.arvense• Catch crops should be included in the rotation to avoid nitrogen leachingIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006Conclusions• In organic farming research, it is not sufficient to study effects seperately, such as:– Perennial weed control– Nitrogen leaching• Unstudied interactions can make the conclusions misleadingIlse A. Rasmussen: Perennial weeds in a crop rotation perspective. 2 March 2006ReferencesGraglia, E., Melander, B., Grøndal, H. & Jensen, R.K. (2004): Effect of repeated hoeing on growth of Cirsium arvense. In: XIIth International conference on weed biology, Dijon, France, pp. 107-112.Graglia, E. & Melander, B. (2005): Mechanical control of Cirsium arvense in organic farming. In: 13th EWRS (European Weed Research Society) Symposium, Pisa, Italy (on CD).Håkansson, S. (2003): Weeds and weed management on arable land – an ecological approach. CABI publishing, Oxon, UK. 274 p.Korsmo, E., Vidme, T. & Fykse, H. (1981): Korsmos ugrasplansjer. Norsk Landbruk/Landbrugsforlaget, Oslo. 295 p.Melander, B., Rasmussen, I.A. & Bertelsen, I. (2005): Integration of Elymus repens control and post-harvest catch crop growing in organic cropping systems. In: 13th EWRS (European Weed Research Society) Symposium, Pisa, Italy (on CD).Rasmussen, I.A., Askegaard, M. & Olesen, J.E. (2005): Long-term organic crop rotation experiments for cereal production – perennial weed control and nitrogen leaching. In: Researching sustainable systems – First Scientific Conference of the International Society of Organic Agriculture Research (ISOFAR), Adelaide, South Australia, pp. 227-230.

Perennial weeds in a crop rotation perspective

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