Perennial weeds in a crop rotation perspective

Transcription

1 Perennial weeds in a crop rotation perspective Ilse A. Rasmussen Dept. of Integrated Crop Protection Danish Institute of Agricultural Sciences Research Centre Flakkebjerg

2 20 cm 40 cm 60 cm Elymus repens Sonchus arvensis Tussilago farfara From Korsmo et al. 1981

3 100 cm 50 cm Cirsium arvense Equisetum arvense From Korsmo et al. 1981

4 I: Initial growth II: Emergence of first shoot III: Dry weight minimum of the whole plant IV: Dry weight minimum of subterranian parts V: Dry weight of subterranian parts larger than at I I II III IV V 1: Original vegetative propagation organs Modified after Håkansson : New vegetative propagation organs 3: Ilse New A. Rasmussen: shoots Perennial under weeds ground in a crop rotation perspective. 4: 2 March Shoots 2006 above ground

5 Elymus repens I II III IV V

6 Tussilago farfara I II III IV V

7 Cirsium arvense I II III IV V

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9 Traditional E. repens control

10 Integrated approach Strategy I: Integrated light Early August, mechanical disintegration Autumn ploughing (20 cm) Crop, grain Suppressive catch crop From Melander et al. 2005

11 Mechanical disintegration P.t.o.-driven rotary cultivation Shallow ploughing Roterende Tine stubble cultivation The Kvik-Up harrow

12 Strategy I: Integrated light E. repens biomass (g m -2 ) a a b Untreated Shal. Pl. Rot. cul. Stub. cul. Kvik-Up c From Melander et al d Effects recorded close to spring barley harvest the following year

13 Strategy I: Integrated light Grain yield (t ha -1 ) No catch crop Radish/ryegr. Cl./vetch E. repens biomass (g m -2 ) From Melander et al. 2005

14 Integrated approach Strategy II: Integrated intensive 1 st July, shallow ploughing (10 cm) Early August, ploughing (20 cm) Following season, ploughing (20 cm) prior to next crop Silage crop Fallow, tine cultivation Suppressive catch crop From Melander et al. 2005

15 Long fallow period Strategy III: Half fallow 1 st July, shallow ploughing Autumn ploughing (20 cm) Silage Crop Fallow, tine cultivation From Melander et al. 2005

16 Traditional Strategy IV: Traditional strategy Early August, onset of post-harvest cultivation Autumn ploughing (20 cm) Crop, grain Post-harvest tine cultivation From Melander et al. 2005

17 Results from 4 experiments E. repens shoots m Integrated intensive Half fallow Traditional From Melander et al June November July

18 Results from 4 experiments Grain yield (t ha -1 ) 5 4,5 4 3,5 3 2,5 2 1,5 1 0,5 0 a Integrated intensive b Half fallow b Traditional From Melander et al Spring barley grain yield the following year

19 Repeated hoeing in spring barley with undersown clover Year one: treatments Hoeing in crop May - July Suppressive catch crop Autumn ploughing (20 cm) Year two: counts/weights + yield Crop: spring barley. From Graglia et al. 2004

20 Repeated hoeing Aboveground biomass (g/m 2 ) Number of hoeings Harvest 2002 Harvest 2003 Hoeing: mid-may mid-july From Graglia et al. 2004

21 Repeated hoeing Yield (100 kg/ha) Harvest 2002 Harvest Number of hoeings Hoeing: medio May-medio July From Graglia et al. 2004

22 Repeated mowing in clover or without crop Year one: establishment Crop: spring barley Suppressive catch crop No catch crop Year two: treatments Mowing in clover/weeds May - July Suppressive catch crop No catch crop Autumn ploughing (20 cm) Year three: counts/weights + yield Crop: spring barley. From Graglia et al. 2005

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24 Mowing weeds without clover Before After

25 Mowing clover Before After

26 Repeated mowing Aboveground biomass (g/m 2 ) Harvest 2002 With out catch crop With catch crop Number of mowings Mowing: mid-may - late July From Graglia et al. 2005

27 Repeated mowing Harvest 2002 Yield (100kg/ha) 60 With out catch crop X With catch crop Y ab ab a b Number of mowings Mowing: mid-may - late July From Graglia et al. 2005

28 Repeated mowing Aboveground biomass (g/m 2 ) Harvest 2003 With out catch crop With catch crop Number of mowings Mowing: mid-may - late July From Graglia et al. 2005

29 Repeated mowing 50 Harvest With out catch crop X With catch crop Y Yield (100kg/ha) Number of mowings Mowing: mid-may - late July From Graglia et al. 2005

30 Organic crop rotation experiments Experimental factors Crop rotation (level of cereals) Catch crop (without/with catch crop) Manure (without/with)

31 Crop rotations Four-year crop rotations are used. The level of cereals and pulses increases from rotation 1 to rotation 4: 1: 1.5 grass-clover + 1 pulse 2: 1 grass-clover + 1 pulse 3: 1 grass-clover 4: 1 pulse

32 Weed 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 crop

33 Weed 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

34 Weed 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 crops

35 Catch crops

36 Nitrate leaching with or without catch crop in rotation with grass-clover Leaching of nitrate-n (kg/ha/year) Coarse sand Loamy sand Without catch crop With catch crop Sandy loam From Rasmussen et al. 2005

37 Control of perennial weeds in stubble

38 N-leaching on coarse sandy soil with or without catch crops and stubble cultivation Leaching of nitrate-n kg ha CC CC - Stubble cult. -CC + Stubble cult. From Rasmussen et al Pulses Cereals

39 E. repens shoots in spring barley on coarse sandy soil with and without catch crops 80 E. repens shoots m CC + Stubble cult. + CC - Stubble cult. From Rasmussen et al Ilse A. Rasmussen: Perennial 1997weeds 1998 in a crop rotation 1999perspective March

40 C. arvense biomass on sandy loam in different crop types with and without catch crops Fresh weight of C. arvense (g m -2 ) CC + Stubble cult. +CC - Stubble cult. From Rasmussen et al Winter wheat Pulses Spring cereals

41 Summary Catch crops should be included in systems with grassclover 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. arvense biomass in our experiments

42 Control of perennial weeds in grass-clover: Summer fallow

43 Concentrations of nitrate-n on coarse sandy soil. Mean of 4 crops, without catch crop, with manure 50 No summer fallow Summer fallow Concentration af nitrate-n (mg/l) From Rasmussen et al. 2005

44 E. repens shoots on coarse sandy soil 60 after grass-clover with or without summer fallow No fallow Fallow E. repens shoots m CC + Stubble cult. + CC - Stubble cult E. repens shoots m First crop Second crop after grass-clover From Rasmussen et al. 2005

45 Summary 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 preferred

46 Nitrate leaching with or without catch crop in rotations with or without grass-clover Leaching of nitrate-n (kg/ha/year) With grass-clover Loamy sand Sandy loam Without grass-clover Without catch crop With catch crop Loamy sand Sandy loam From Rasmussen et al. 2005

47 C. arvense biomass on sandy loam in different crop types in two rotations Fresh weight of C. arvense, g m With grass-clover Without grass-clover From Rasmussen et al Winter wheat Pulses Spring cereals

48 Summary Grass-clover can be managed to reduce C. arvense Catch crops should be included in the rotation to avoid nitrogen leaching

49 Conclusions 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 misleading

50 References Graglia, 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 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