Limited Seed and Seed Yield Response of Calendula to Applied Nitrogen Does Not Justify Risk of Environmental Damage from High Urea Application Rates

Jane M. F. Johnson, Russ W. Gesch and Nancy W. Barbour
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Jane M. F. Johnson: USDA-Agricultural Research Service-North Central Soil Conservation Research Laboratory, Morris, MN 56267, USA
Russ W. Gesch: USDA-Agricultural Research Service-North Central Soil Conservation Research Laboratory, Morris, MN 56267, USA
Nancy W. Barbour: USDA-Agricultural Research Service-North Central Soil Conservation Research Laboratory, Morris, MN 56267, USA

Agriculture, 2018, vol. 8, issue 3, 1-13

Abstract: Calendula ( Calendula officinalis L.) seed, due to its high calendic acid content, is recognized as a potential environmentally safe substitute for volatile organic compounds. Agronomic guidelines for nitrogen (N) management to produce calendula seed oil on a commercial scale are limited. Post-harvest soil N has the potential to move off-farm and contribute to water quality degradation (e.g., hypoxia in the Gulf of Mexico). Establishing N management guidelines should consider agronomic response and potential environmental risk. Calendula seed and oil yield, oil content, harvest index, N use, seed N use efficiency, oil N use efficiency, agronomic efficiency, vegetative growth, and the amount of residual soil-N following harvest response to five urea N rates (0, 34, 67, 134, and 202 kg N ha −1 ) were assessed in a replicated field study repeated for two growing seasons. Seed yield increased with N rate, but because of the low N conversion efficiency, there appeared to be minimal yield gains in applying N beyond 34 kg ha −1 . The lowest amount of soil-N left underutilized in the soil was predicted to occur at 39 kg N ha −1 and was adequate for seed and seed oil commercial calendula production on a Mollisol in the Northern Midwest United States.

Keywords: industrial seed-oil; nitrogen use efficiency; agronomic efficiency; soil nitrogen; pot marigold (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2018
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