Physical and Cultural Weed Control Working Group of - European ...

More documents

Recommendations

Info

9 th EWRS Workshop on Physical and Cultural Weed Control 42 Samsun, Turkey, 28 – 30 March 2011 Weed management in organic and herbicide-free systems under conservation tillage: the ultimate challenge A. Légère 1 , F.C. Stevenson 2 , A. Vanasse 3 , O. Lalonde 3 1 Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, SK, Canada S7N 0X2 Email: anne.legere@agr.gc.ca 2 Private Consultant, Saskatoon, SK, Canada S7N 3T6 3 Université Laval, Québec, QC, Canada The success of conservation tillage in organic farming depends on high standards of management, including diversified crop rotations, and an IWM approach. A study was initiated at La Pocatière, Québec, in 2007 to compare the effects a herbicide-free (HF) system and a system based on agronomic practices typical of organic agriculture (ORG) to that of cropping systems using either regular (CONV) or GM crops on weed communities and crop yield. The cropping systems were applied to three well established (since 1987) tillage treatments (MP: moldboard plow, CP: chisel plow, NT: no-till) in a four-year barley (2007) - red clover forage (2008) - corn (2009) - soybean (2010) rotation. Barley yields in 2007 were similar across all treatments (p>0.250) in spite of greater weed density as tillage was reduced (p
9 th EWRS Workshop on Physical and Cultural Weed Control 43 Samsun, Turkey, 28 – 30 March 2011 Crop rotation as the ultimate cultural practice: 18 years of cereal yield stability in three tillage systems A. Légère 1 , F.C. Stevenson 2 1 Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, SK, Canada S7N 0X2 Email: anne.legere@agr.gc.ca 2 Private Consultant, Saskatoon, SK, Canada S7N 3T6 Current agricultural systems are often based on crop monocultures or very short rotations, in spite of little if any benefits from agronomic, environmental, and even economic perspectives compared to well planned crop rotations. The benefits of diversified crop rotations have been extensively documented. Our objective is to demonstrate that crop rotation can ensure greater and more stable crop yield over time, even when using conservation tillage practices. Crop yield is determined by its various components, each of which is being affected by agroenvironmental conditions at different times during the growth season. For cereal crops, seed density (number of crop plants x number of flowers per head x number of head per plant) is determined mainly in the period prior to weed management operations whereas grain weight (1000-seed wt) will be affected by conditions in the post weed management period, including the effects of potential competition from residual weed communities during grain filling. Using a grouping methodology based on means and coefficient of variation (c.v.), we examined crop rotation and tillage effects on cereal yield and yield components from a long-term conservation tillage study, conducted at La Pocatière Québec. Two time periods were examined: a first phase (1988-1994) which compared a 2-yr cereal-forage rotation to a cereal monoculture, and a second phase (1998- 2005) which compared a 4-yr cereal-oilseed rotation to a cereal monoculture. Tillage treatments included: moldboard plow (MP), chisel plow (CP), and no-till (NT). On average, seed density and yields were greater and less variable in the second phase (c.v. = 28% than in the first phase (c.v. = 41%). Seed density and yields from rotation treatments were greater and generally less variable than that from the monoculture. According to the groupings defined by the average of means and c.v. over time, first-phase rotation-MP and rotation-NT were optimum treatments, providing high yields with low variability (3732 kg ha-1, 24.4% and 3397 kg ha-1, 33.4%, respectively), whereas the monoculture-CP provided the lowest yield with the highest variability (2450 kg ha-1, 50.6%). In the second phase, rotation yields averaged 3946 kg ha-1, with a c.v. of 19.3%, compared to 3155 kg ha-1, with a c.v. of 35.6% in the monoculture. In both phases, variability of seed density was in the same range as that for yield, and treatment effects followed very similar trends. Conversely, values for 1000-grain wt were much less variable, with an average c.v. of 7% and 14%, in the first and second phase, respectively. Values for 1000-grain wt were consistently greater in the crop rotation than in the monoculture. Overall, cereal yields were influenced more by early (seed density) than late (1000-seed wt) season agro-environmental conditions, which suggested minor effects of residual weed populations during the grain filling period in crop rotation treatments. Crop rotation ensured greater and more stable yields over time than the monoculture. These benefits were slightly greater in the 4-yr crop rotation (second study phase), in spite of greater environmental variability compared to conditions during the first study phase. Whether the crop rotation effect in the second phase is attributable solely to the cereal-oilseed rotation or to the cumulative effects of both cereal-oilseed and previous cereal-forage rotation could not be determined. Diversified crop rotations proved beneficial, particularly in these aging conservation tillage systems.
Page 2 and 3: Disclaimer The contents of these pr
Page 4 and 5: 9 th EWRS Workshop on Physical and
Page 11 and 12: General presentations
Page 51: 9 th EWRS Workshop on Physical and
Page 103 and 104:
9 th EWRS Workshop on Physical and
Page 105 and 106:
Page 107:
show all

Physical and Cultural Weed Control Working Group of - European ...

Create successful ePaper yourself

Delete template?

Save as template?