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Fate of Nitrate in Organic Crop-Livestock Systems With Direct and Conventionally Seeded Catch Crops.

Poster Number 705

Tuesday, November 5, 2013
Tampa Convention Center, East Hall, Third Floor

Harun Cicek, Plant Science, University of Manitoba, Winnipeg, MB, Canada and Martin H. Entz, Department of Plant Science, University of Manitoba, Winnipeg, MB, Canada
Benefits of green manure can be further supplemented by livestock grazing. However, readily available NO3- from livestock manure can potentially be lost from the system by leaching from the root zone. The objective of this study was to determine how two management factors; type of catch crop and tillage; affected NO3- leaching and N uptake in a subsequent crop. A three year experiment was established in Manitoba, Canada in 2010 and repeated in 2011. In the first year, upon grazing (termination) of mixture of pea/oat/soybean green manure, catch crops (barley and oil seed radish) were seeded directly (reduced-till) or after cultivation (tilled). Control plots had no catch crops. Second and third year tests crops were wheat and fall rye. Measurements included aboveground biomass and N content of catch crops and wheat, as well as wheat grain. Soil samples were taken to 120 cm, before grazing, after grazing, upon termination of catch crops, before seeding wheat and after wheat harvest. In 2010 the oil seed radish catch crop biomass contained significantly more N than barley; 85 kg ha-1 and 73 kg ha-1 respectively. Higher soil profile N in control (117 kg ha-1) vs catch crop treatments (average 59 kg ha-1) suggests reduced N leaching with catch crops. Significantly lower wheat yield in the catch crop vs control plot suggests that catch crops restricted N availability to the following crop. No significant tillage effects were observed. Catch crops reduced leaching of NO3- regardless of tillage system, but also reduced wheat yield.
See more from this Division: C06 Forage and Grazinglands
See more from this Session: General Forage and Grazinglands: II

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