Nitrogen management for calendula that meets agronomic and environmental goals

Authors: Johnson, Jane; Gesch, Russell - Russ; BARBOUR, NANCY - Retired ARS Employee

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/7/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Calendula (Calendula officinalis L.) is an emerging oil seed, which may provide an alternative for restricted volatile organic chemicals. Nitrogen fertilizer recommendations for commercial cultivation are needed. Nitrogen fertilizer guidelines should go beyond maximum yield to reflect prudent N management, which balance agronomic yield and environmental risk. Crop and residual soil N response urea applied at five rates (0, 34, 67, 134, and 202 kg N ha-1) were assessed in a replicated field study, that was repeated during two growing seasons. The study had four objectives: identify the N rate for maximum agronomic yield, assess calendula’s efficiency acquiring and utilizing N, assess soil N after harvest, and utilize this information to provide a N management recommendation that optimized yield while minimizing risk of N loss to the environment. Seed and seed oil yield response to N rate could be described using a quadratic function, solving the maximum inflection point of the quadratic function suggested a maximum occurred at 194 and 183 kg N ha-1 rate for seed and seed oil, respectively. Seed N use efficiency, oil N use efficiency, and agronomic efficiency suggested little return per unit N applied beyond 34 kg N ha-1. Residual soil N could be described with quadratic function, in which N applied above 39 kg N ha-1 substantially increase the amount available to leak into the environment. Based on these results, it suggested that N application be limited to 39 kg N ha-1 as agronomic gains were few and environmental risk increase beyond this amount.