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1. Compare a high intensity stocked vegetable rotational system (3 vegetable crops in 4 years, with grazing and manure cycling) with a low intensity stockless vegetable rotational system (1 vegetable crop in 4 years with leguminous cover crops)

• Compare crop quality and yield
• Analyse costs/revenues of inputs and outputs

2. Evaluate the contribution of various legume varieties with differing N release patterns to fertility of companion plantings of vegetables

• Use ion exchange membrane technology to evaluate in-season N availability and nutrient cycling patterns
• Use tissue N sampling to assist with interpretation of ion exchange data
• Elaborate simple N flow patterns within a red clover/corn companion planting system

Can intensive organic vegetable cropping systems be sustainable in the long term without livestock integration and the accompanying manure inputs? This is a much debated question in organic agriculture across the globe. In Canada, particularly the Maritimes, organic vegetables are currently most often produced on farms without livestock, and often at distances from neighbouring livestock farms that would make integration prohibitively costly.

In 2007, a long term organic vegetable rotations experiment was set up at AAFC Bouctouche NB as part of a larger Eastern Canada multi-sites project looking at organic vegetable systems. The Bouctouche site was designed to allow long term comparisons of two systems: a high intensity stocked vegetable rotation (4 yr rotation, 3 vegetable crops, grazing and manure inputs, and innovative strategies such as relay cropping and companion planting), and a low intensity vegetable stockless rotation (4 yr rotation, 1 vegetable crop and cover crops). This proposed work seeks to use that established site to begin to understand differences in overall productivity as well as differences in crop qualities between a high intensity stocked and a low intensity stockless system over the long term. In the short term, this activity will use measurements of yield and crop quality in the two rotational systems, and will calculate the values of inputs and outputs, including, in conjunction with Alan Fredeen and John Duynisveld, the livestock side, in order to present a simple cost/revenue analysis of the systems, information which is often lacking in crop research experimentation but is key in the decision-making of organic farmers.

The activity will also examine how red clover plantings may be used in organic agriculture to deliver nitrogen to companion plantings of a heavy feeding vegetable such as sweet corn. Work by Dr. Yousef Papadopoulos has determined that within a legume species, certain varieties have distinct temporal patterns of N release; the conventional understanding that a legume's N release was mostly limited to plough down is true for certain varieties, while others release N over the course of their growth. Thus an opportunity exists to tailor N availability with N needs of a companion vegetable by legume variety selection. A detailed look at N flow between red clover varieties with different N release patterns and a companion vegetable of sweet corn will be conducted using several techniques, including ion exchange membrane technology to examine nutrient release over the growing season, soil and tissue N sampling, and a collaboration with Yousef Papadopoulos for the use of N isotopes to track N flow.

• Characterization of nitrogen transfer from diverse red clover populations to companion bluegrass and impact on soil nitrogen dynamics under field conditions
  • Plant Canada Conference. 2011
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  • Canadian Journal of Plant Science (2012) 92: 1163-1173
• Cross Canada green manure use on organic vegetable farms
  • OACC News Article. 2011
    
• [PDF - 827 kB]
  • Joint Conference of the North American Alfalfa Improvement Conference, Trifolium & Grass Breeders. 2012
• Innovative agronomic techniques for growing profitable high quality organic sweet corn
  • Plant Canada Conference. 2011
• Nitrogen fixation and transfer from red clover (Trifolium pratense L.) cultivars to companion bluegrass (Poa pratensis L.) under field conditions
  • CSA-CSH-CAA-AIC Conference. 2012

• • Advances in Agronomy (2001) 70: 261-262
• • Plant and Soil (1992) 141: 155-175
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• • Arid Soil Research and Rehabilitation (1993) 7: 1-13
• • Agriculture, Ecosystems and Environment (1996) 57: 189-196
• • Nutrient Cycling in Agroecosystems (1994) 37: 227-234
• • Archives of Agronomy and Soil Science (2003) 49: 465-483
• • Soil Use and Management (2002) 18: 239-247
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• • 16th IFOAM Organic World Congress. 2008