Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2012
Publication Date: 1/1/2013
Citation: Johnson, J.M., Gesch, R.W. 2013. Calendula and camelina response to nitrogen fertility. Industrial Crops and Products. 43:684-691.
Interpretive Summary: Domestically-grown, non-food use crops are needed to replace imported oil and other materials for energy and industrial products. Calendula and camelina are such potential crops that can produce oil in their seeds that can replace imported oils. However, information on how much nitrogen (N) fertilizer should be applied to optimize oil and seed yield production is needed. Under-fertilization can sacrifice potential yield, while over-fertilization can have negative economic and environmental consequences. The objective was to evaluate growth response and determine preliminary N fertility requirements of calendula and camelina. A greenhouse study provided an initial estimate of how much N fertilizer is needed to grow these crops in the field. Both crops were grown in pots and provided the equivalent of zero (control) to 234 pounds per acre of N as urea. The yield of both crops increased when provided urea fertilizer until the rate exceeded 120 pounds per acre. Although seed yield increased in camelina with increased N fertilizer, its seed oil content decreased. Calendula had greater N uptake efficiency compared to camelina. Camelina stored N in shoots, but calendula stored N in roots and shoots. Calendula had twice the root biomass and more than four times greater root to shoot ratio compared to camelina. Although both crops responded favorably to increased N fertility, the response was not strong. This indicates that fertilizing to maximize agronomic yield might not translate to maximum economic return given the high cost of N fertilizer. Results of this study provide an important first step in developing fertilizer recommendations for field production of these two oil-seed crops. Researchers will benefit from expanding basic and applied research to the field. Ultimately, producers, crop consultants and extension personnel will benefit from sound fertilizer guidelines.
Technical Abstract: The emerging oil-seed crops calendula (Calendula officinalis) and camelina (Camelina sativa L.) can provide a domestic, renewable, non-food alternative to imported oil sources for bioenergy and industrial purposes. However, very little information exists concerning nitrogen (N) fertilizer guidelines for these emerging oilseed crops. Therefore, a replicated greenhouse study was conducted to assess the growth and yield response of calendula and camelina to N fertility. Plants were grown in pots and treatments consisted of fertilizing with urea at 0, 0.1, 0.2, 0.5 and 1.0 g N pot-1, corresponding to a field area equivalent rate of 0, 26, 52, 130, and 260 kg ha-1. Reproductive (i.e., biomass, seed yield, seed-oil yield, and seed-oil content) and vegetative parameters (i.e., root and shoot biomass, N concentration and uptake) were used to assess crop response to N-fertility. Both calendula capitula (flower and seed heads) biomass yield and camelina seed yield showed a positive, quadratic (r2 = 0.93 and 0.99, respectively) response to N fertility with maximum yields occurring at 0.5 g N pot-1. In contrast, camelina seed-oil content showed a quadratic decline (r2=0.99) from 390 to 360g kg-1 in response to N fertility. Mean comparisons analysis indicated insignificant yield differences among the 0.1, 0.2, 0.5 g N pot-1 treatments for either crop. Nitrogen uptake efficiency of aboveground vegetative biomass was greater for calendula (29 to 53%) than camelina (about 19 to 29%). The results of this study indicated that 0.5 g N pot-1, equivalent to 130 kg N ha-1 was needed for maximum yield for both crops. Camelina seed oil content (g kg-1) declined with increased N fertility, but an increase in seed yield compensated such that oil yield generally increased with N fertility.