Agronomy 2013, 3(1), 181-199; doi:10.3390/agronomy3010181
Article

Evaluation of Post-Harvest Organic Carbon Amendments as a Strategy to Minimize Nitrogen Losses in Cole Crop Production

1 School of Environmental Sciences, University of Guelph, Ridgetown Campus, Ridgetown, Ontario, N0P 2C0, Canada 2 Department of Food, Agriculture and Resource Economics, University of Guelph, Ridgetown Campus, Ridgetown, Ontario, N0P 2C0, Canada
* Author to whom correspondence should be addressed.
Received: 27 November 2012; in revised form: 10 January 2013 / Accepted: 4 February 2013 / Published: 18 February 2013
(This article belongs to the Special Issue Sustainable Crop Production)
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Abstract: Cole crops (Brassica vegetables) can pose a significant risk for N losses during the post-harvest period due to substantial amounts of readily mineralizable N in crop residues. Amending the soil with organic C has the potential to immobilize N and thereby reduce the risk for N losses. Four field trials were conducted to determine the effects of organic C amendments (OCA) on N dynamics and spring wheat (Triticum durum L.) harvest parameters proceeding early- and late-broccoli (Brassica olecerea var italica L.) systems in 2009 and 2010. The experimental controls represented the traditional grower practice of incorporated broccoli crop residue (CR-control) and the pre-plant application of N fertilizer (CRN-control) to subsequent spring wheat. Alternative practices were compared to the controls, which included broccoli crop residue removal (CR-removal), an oat (Avena sativa L.) cover crop (CC-oat), and three different OCA of wheat straw (OCA-straw), yard waste (OCA-yard), or used cooking oil (OCA-oil). The treatments, which demonstrated reduced autumn soil mineral N (SMN) concentrations after broccoli harvest, relative to the CR-control, were CR-removal, OCA-straw, and OCA-oil. Although CR-removal and OCA-straw indicated a reduced potential for autumn soil N losses in the early-broccoli system, these practices are not recommended for growers because subsequent spring wheat yield and profit margins were reduced compared to the CR- and CRN-controls. The OCA-oil reduced autumn SMN concentrations by 53 to 112 kg N ha−1 relative to the CR-control after both early- and late-broccoli harvest, suggesting a larger potential for reduced autumn soil N losses, compared to all other treatments. No detrimental effects resulted from the OCA-oil treatment on the subsequent spring yield or grain N. The OCA-oil reduced spring wheat profit margins relative to the CR-control, like the OCA-straw and CR-removal treatments, however profit margins were similar between the OCA-oil and the CRN-control. Therefore, in areas with a high risk of environmental N contamination, growers should consider the OCA-oil practice after cole crop harvest to minimize the risk of N losses.
Keywords: nitrogen immobilization; broccoli; soil amendment; sustainable agriculture; profit margins

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MDPI and ACS Style

Congreves, K.A.; Vyn, R.J.; Van Eerd, L.L. Evaluation of Post-Harvest Organic Carbon Amendments as a Strategy to Minimize Nitrogen Losses in Cole Crop Production. Agronomy 2013, 3, 181-199.

AMA Style

Congreves KA, Vyn RJ, Van Eerd LL. Evaluation of Post-Harvest Organic Carbon Amendments as a Strategy to Minimize Nitrogen Losses in Cole Crop Production. Agronomy. 2013; 3(1):181-199.

Chicago/Turabian Style

Congreves, Katelyn A.; Vyn, Richard J.; Van Eerd, Laura L. 2013. "Evaluation of Post-Harvest Organic Carbon Amendments as a Strategy to Minimize Nitrogen Losses in Cole Crop Production." Agronomy 3, no. 1: 181-199.

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