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

Agronomy

Katelyn A. Congreves¹  Richard J. Vyn² 

[1] School of Environmental Sciences, University of Guelph, Ridgetown Campus, Ridgetown, Ontario, N0P 2C0, Canada; E-Mail:;Department of Food, Agriculture and Resource Economics, University of Guelph, Ridgetown Campus, Ridgetown, Ontario, N0P 2C0, Canada; E-Mail:

关键词: nitrogen immobilization;    broccoli;    soil amendment;    sustainable agriculture;    profit margins;   

DOI  :  10.3390/agronomy3010181

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.