Crop sequence, crop protection and fertility management effects on weed cover in an organic/conventional farm management trial

A survey of 128 plots, in 2008, of a trial where the effects of crop protection can be separated from those of fertility management, generated weed cover data within six crops (winter wheat, winter barley, spring barley, potatoes, cabbages and a grass/clover ley). The effects of the 2008 crop types, of the two preceding crops and of organic and conventional crop protection and fertility management, were assessed using mixed-effects models and constrained ordination. Cover data for 22 weed species and for monocotyledon, dicotyledon, annual, perennial and total weed cover were used. Cover of 15 weed species, and of the five weed groups, was significantly affected by 2008 crops, with cover highest in spring beans and cabbage. Nine and four weed species 2008 cover were significantly related to crops grown in 2007 and 2006 respectively, as were dicotyledon, annual and total weed cover, but not monocotyledon or perennial cover. Cover of 15 species, and the five groups, was significantly higher in plots with organic crop protection, but only eight species and annuals were significantly affected by fertility management. Crop:crop protection produced the most significant interactions with most cover in organically managed plots. Five species, perennials and total weed cover produced significant three-factor models. The greatest weed cover was in organic crop protected but conventionally fertilised spring barley and the least in totally conventional winter barley. Other factors such as crop density and mechanical weeding also affected 2008 weed cover. The ordination indicated that most of the 22 species were strongly associated with crops from all three years. The sequence of crops in the rotation had a profound effect on weed cover. Where three spring-sown, difficult to weed, crops were grown in sequence (spring beans, potatoes and vegetables, spring barley) weed cover increased. However, cover was limited in grass/clover and some cereal plots with different preceding crops. Models predicting weed cover may need to take into account crop sequences within crop rotations, as well as the more usual management inputs.

[1]  J. Holland,et al.  A review of invertebrates and seed‐bearing plants as food for farmland birds in Europe , 2006 .

[2]  Lisa Norton,et al.  Environmental and management factors determining weed species composition and diversity in France , 2008 .

[3]  R. Blackshaw,et al.  Nitrogen Fertilizer Rate Effects on Weed Competitiveness is Species Dependent , 2008, Weed Science.

[4]  Niels Holst,et al.  Field weed population dynamics : a review of model approaches and applications , 2007 .

[5]  Jonathan Storkey,et al.  Using Assembly Theory to Explain Changes in a Weed Flora in Response to Agricultural Intensification , 2010, Weed Science.

[6]  D. Bates,et al.  Mixed-Effects Models in S and S-PLUS , 2001 .

[7]  L. K. Ward,et al.  The role of weeds in supporting biological diversity within crop fields , 2003 .

[8]  Randy L. Anderson,et al.  A multi-tactic approach to manage weed population dynamics in crop rotations , 2005 .

[9]  C. Stace,et al.  New Flora Of The British Isles , 1998 .

[10]  D. J. Webb,et al.  The dynamics of experimental arable weed communities under different management practices , 1996 .

[11]  J. Weiner,et al.  Effects of density and spatial pattern of winter wheat on suppression of different weed species , 2005, Weed Science.

[12]  Teja Tscharntke,et al.  The effects of landscape complexity on arable weed species diversity in organic and conventional farming , 2005 .

[13]  N. Ziadi,et al.  Contrasting Responses of Weed Communities and Crops to 12 Years of tillage and Fertilization Treatments , 2008, Weed Technology.

[14]  J. Cooper,et al.  Effects of organic and ‘low input’ production methods on food quality and safety , 2007 .

[15]  Randy L. Anderson,et al.  Weed Community Response to Crop Rotations in Western South Dakota , 2007, Weed Technology.

[16]  C. Critchley,et al.  The effects of annual cultivation on plant community composition of uncropped arable field boundary strips , 2006 .

[17]  P. Milberg,et al.  Weed performance in crop rotations with and without leys and at different nitrogen levels , 1996 .

[18]  R. Anderson.  Managing weeds with a dualistic approach of prevention and control. A review , 2011, Agronomy for Sustainable Development.

[19]  Richard G. Smith,et al.  Weed–crop competition relationships differ between organic and conventional cropping systems , 2009 .

[20]  David A. Mortensen,et al.  Elucidating the apparent maize tolerance to weed competition in long‐term organically managed systems , 2010 .

[21]  J. L. Capinera,et al.  Relationships between insect pests and weeds: an evolutionary perspective , 2005, Weed Science.

[22]  Richard G. FitzJohn,et al.  Predicting weed distribution at the landscape scale: using naturalized Brassica as a model system , 2008 .

[23]  Jannie Olsen,et al.  Crop Density, Sowing Pattern, and Nitrogen Fertilization Effects on Weed Suppression and Yield In Spring Wheat , 2008, Weed Science.

[24]  C.J.F. ter Braak,et al.  CANOCO Reference Manual and User's Guide to Canoco for Windows: Software for Canonical Community Ordination (Version 4) , 1998 .

[25]  J. Isselstein,et al.  An on-farm approach to investigate the impact of diversified crop rotations on weed species richness and composition in winter wheat , 2009 .

[26]  Santiago L. Poggio,et al.  Structure of weed communities occurring in monoculture and intercropping of field pea and barley , 2005 .

[27]  Richard G. Smith,et al.  Weed community and corn yield variability in diverse management systems , 2006, Weed Science.

[28]  D. Clements,et al.  Promotion of weed species diversity and reduction of weed seedbanks with conservation tillage and crop rotation , 2006, Weed Science.

[29]  Richard G. Smith,et al.  Assembly of weed communities along a crop diversity gradient , 2007 .

[30]  A. Mead,et al.  Organic weed management: A review of the current UK farmer perspective , 2007 .

[31]  Robert E. Blackshaw,et al.  Differential response of weed species to added nitrogen , 2003, Weed Science.

[32]  B. Maxwell,et al.  Using Species-Area Curves to Examine Weed Communities in Organic and Conventional Spring Wheat Systems , 2009, Weed Science.

[33]  A. Davis,et al.  Effect of Fertilizer Nitrogen on Weed Emergence and Growth , 2008, Weed Science.

[34]  P. Milberg,et al.  A Survey of Weeds in Organic Farming in Sweden , 2000 .

[35]  R. Y. van der Weide,et al.  Innovation in mechanical weed control in crop rows , 2008 .

[36]  Hans W. Griepentrog,et al.  Suppression of weeds by spring wheat Triticum aestivum increases with crop density and spatial uniformity , 2001 .

[37]  Richard G. Smith.  Timing of tillage is an important filter on the assembly of weed communities , 2006, Weed Science.

[38]  T. Hyvönen,et al.  Arable weeds as indicators of agricultural intensity – A case study from Finland , 2008 .

[39]  R. Anderson.  Impact of Preceding Crop and Cultural Practices on Rye Growth in Winter Wheat , 2009, Weed Technology.

[40]  E. Marshall.  The impact of landscape structure and sown grass margin strips on weed assemblages in arable crops and their boundaries. , 2009 .

[41]  David A. Mortensen,et al.  A new hypothesis for the functional role of diversity in mediating resource pools and weed–crop competition in agroecosystems , 2010 .

[42]  P. Jeanneret,et al.  Long-term weed community dynamics in Swiss organic and integrated farming systems , 2008 .

[43]  Ter Braak,et al.  Canoco reference manual and CanoDraw for Windows user''s guide: software for canonical community ord , 2002 .

[44]  William J. Sutherland,et al.  Modelling the effects of management on population dynamics: some lessons from annual weeds. , 2008 .

[45]  A. C. Grundy,et al.  Non‐chemical weed management in organic farming systems , 2001 .

[46]  M. Kropff,et al.  The influence of nitrogen supply on the ability of wheat and potato to suppress Stellaria media growth and reproduction , 2002 .

[47]  H. Beckie,et al.  Ongoing Development of Integrated Weed Management Systems on the Canadian Prairies , 2008, Weed Science.

[48]  A. B. Hald.  The impact of changing the season in which cereals are sown on the diversity of the weed flora in rotational fields in Denmark , 1999 .

[49]  Michael J. Crawley,et al.  The R book , 2022 .

[50]  L. Wiles,et al.  Modeling With Limited Data: The Influence of Crop Rotation and Management on Weed Communities and Crop Yield Loss , 2009, Weed Science.

[51]  A. B. Hald,et al.  Weed vegetation (wild flora) of long established organic versus conventional cereal fields in Denmark , 1999 .

[52]  Philip A. Stephens,et al.  Predictive models of weed population dynamics , 2009 .