Spring camelina N rate: Balancing agronomics and environmental risk in United States Corn Belt

Authors: Johnson, Jane; Gesch, Russell - Russ; Barbour, Nancy

Submitted to: Archives of Agronomy and Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2018
Publication Date: 10/9/2018
Publication URL: http://handle.nal.usda.gov/10113/6331842
Citation: Johnson, J.M., Gesch, R.W., Barbour, N.W. 2018. Spring camelina N rate: Balancing agronomics and environmental risk in United States Corn Belt. Archives of Agronomy and Soil Science. https://doi.org/10.1080/03650340.2018.1519803.
DOI: https://doi.org/10.1080/03650340.2018.1519803

Interpretive Summary: Camelina is a source of industrial and food oils that can be grown in the USA. It has and is being used to make "green" jet fuel that fully meets all ASTM standards for aviation fuel. It has been grown for centuries for many uses, including food, cosmetics and medicinal. However little information is available to growing this crop on a broader scale to support new uses. In particular, little is known about nitrogen fertilizer needs when growing camelina as an oilseed crop in Minnesota. Therefore, a two-year study was done to find out how much nitrogen fertilizer should be added when growing this crop. We tested five rates of the nitrogen fertilizer called urea. Grain yield, oil content, oil yield, harvest index, and the crop's nitrogen use efficiency were determined. These measures provide information on how effectively this crop used nitrogen to produce seeds and make oil. The amount of residual nitrogen in the soil was also measured. Grain and oil yield increased with more nitrogen added to the soil. Maximum grain yield (1290 pounds per acre) occurred at a nitrogen application rate of 116 pounds per acre, and oil yield (519 pounds per acre) was greatest at 113 pounds nitrogen applied per acre. Indicators of how efficiently camelina used nitrogen fertilizer declined with increasing nitrogen application and the amount of nitrogen left in the soil increased. Nitrogen left behind in the soil can easily be lost over the winter. Nitrogen is an expensive input to producers so unused nitrogen represents reduction in potential profits. Based on these results, it is recommended that no more than 62 pounds of nitrogen per acre is necessary for efficient grain production of camelina in the northern Corn Belt region of the USA. This information is used for producers that wish to grow this crop and get the most use of the nitrogen applied.

Technical Abstract: Camelina (Camelina sativa (L.) Crantz) seed oil has desirable properties for production of advanced biofuels including jet fuel. Its oil also contains high levels of linolenic acid, an omega-3 fatty acid, and tocopherol, making it suitable as a healthy cooking oil. Although the crop has been grown for food and other uses for centuries, basic agronomic information such as nitrogen (N) fertilizer requirements are scant for mass cultivation to support emerging uses. Under fertilization results in poor yield, while over fertilization results in unnecessary input costs and increases the risk of N losses into the environment adding to water and air quality concerns. Therefore, a replicated N response study was conducted on a Barnes loam soil in western Minnesota USA for two growing seasons to 1) determine seed and oil yield, seed oil content, plant growth response to N fertilizer, 2) determine indices of nitrogen use efficiency, and 3) measure post-harvest residual soil N from field-grown camelina. Yield response to N fertilization was described with a quadratic function. Maximum seed yield (1450 kg ha-1) occurred at 130 kg N ha-1 and maximum oil yield (580 kg ha-1) occurred at 126 kg N ha-1. Seed oil concentration averaged 40.2 g kg-1. Agronomic efficiency of seed production (the increase in seed yield with N compared to control without N applied per unit N) declined above 67 kg N ha-1, while post-harvest soil N increased as N-rate increased. Thus, considering agronomic efficiency and post-harvest residual soil N, application rates of N above about 70 kg ha-1 are not recommended for relatively high organic matter soils in the northern Corn Belt region USA.