|September harvest of European hazelnuts in New Jersey. Photo: Thomas Molnar.|
Hazelnuts, also known as filberts (Corylus spp.), are a perennial tree crop that have been grown for many years in Mediterranean environments as a tree nut for food. Because of its adaptation to less productive soil and its high quantity and quality of oil, the species may hold potential as a biofuel crop if current disease problems that limit its adaptation can be overcome.
This article is written for information purposes only and should not be considered a recommendation to plant hazelnuts for biofuel production. Hazelnuts, unlike soybeans and other traditional oil crops, have not been grown commercially for oil for biodiesel, and more research, both agronomic and economic, is needed.
Current Potential for Use as a Biofuel
Hazelnut merits investigation and development as a sustainable and high-yielding feedstock for biodiesel and other oleochemicals. Calculations from production in the Pacific Northwest suggest 90 gallons of oil per acre could be realized under current systems. This is greater than the U.S. average of approximately 50 gal./acre from soybeans. Production based on the development and commercialization of new high-yielding and much more widely adapted varieties could lead to oil yields of over 125 gal./acre.
|Commercial hazelnut orchard with single-stem pruned trees in Eugene, Oregon. Photo: Thomas Molnar.|
In addition to oil yield, hazelnut oil has a unique fatty acid composition (high monounsaturated fatty acids), good thermal stability, and low temperature properties that should make it competitive with soybean oil for a number of applications (see Table 1). The high-quality protein meal remaining after oil extraction may add substantial value to the hazelnut crop in the form of animal feed or in other products such as baked goods or supplement bars. However, its use in this manner has not yet been fully evaluated. The lower fertilizer and pesticide requirements of hazelnuts compared to other biofuel crops could reduce biofuel production costs. Hazelnut groves are long-lived and should significantly reduce erosion and fertilizer leaching and increase soil organic matter, especially on soils not suitable for the sustainable production of annual food and feed crops.
|Table 1. Characteristics of hybrid hazelnut and soybean oil (adapted from Xu et al., 2007).|
|Characteristics of the oil||Soybean oil||Hybrid hazelnut oil|
|Crude oil fat (%)||~20||51.4-75.1|
|Fatty acid composition (%)|
|Iodine value (g iodine absorbed/100g sample)||130.4||90.6-97.4|
|Oxidative onset temperature (ºC)||148.4||184.7-190.4|
|Cloud point (ºC)||-9.9||-12.4 - 14.9|
|Kinematic viscosity at 22ºC (mm2/s)||58.9 ± 3.3||65.7± 2.2|
|The non-clasping nut clusters of the commercial European hazelnut, Corylus avellana, release nuts at maturity. Photo: Thomas Molnar.|
The European hazelnut, Corylus avellana, is the perennial tree species grown for commercial nut production. It has large, high-quality nuts but is generally cold sensitive. There are two wild hazelnut species native to the northeastern United States (C. americana and C. cornuta), although both produce tiny, thick-shelled nuts of little commercial value. New, disease-resistant European hazelnut cultivars, as well as select hybrids between the American and European species, can combine improved nut and kernel traits with cold hardiness, especially in the advanced backcross generations. Commercial hazelnuts have a shelling percentage of 50% to 60% and kernel oil content of over 60% (FAOStat, 2009; Ebrahem et al., 1994; Mehlenbacher, 2003).
The top hazelnut-producing country in the world is Turkey, which produces 60% to 70% of the world’s crop (world total was 1,052,001 metric tonnes in 2008). Turkey is followed by Italy, which produces around 17% of the world’s total, and then the United States, which produces less than 5% (FAOStat 2009). Only about 10% of the world crop is sold in-shell; the remaining is cracked and sold as kernels for baked goods, chocolates, and other confections. Currently, around 99% of the U.S. hazelnut crop is produced in the Willamette Valley of Oregon (Mehlenbacher and Olsen, 1997; Mehlenbacher, 2005).
|The non-commercial fleshy nut cluster of wild hazelnut, Corylus americana, retains nuts at maturity. Photo: Thomas Molnar.|
While European hazelnut production has been attempted in northeastern North America since colonial times, there has been no commercial success in this region primarily due to a native disease called eastern filbert blight (EFB), which is incited by the fungus Anisogramma anomala (Fuller, 1908; Thompson et al., 1996). EFB causes severe stem cankering and subsequent death of most European hazelnut plants in four to seven years after exposure to A. anomala. The disease is found closely associated with Corylus americana, whose wide native range includes much of the eastern half of the United States (Gleason and Cronquist, 1998). C. americana is very tolerant of EFB and subsequently acts as a reservoir of inoculum to infect susceptible European hazelnuts planted across its range. Fortunately, recent research has identified a number of sources of resistance to EFB within Corylus avellana, which may lead to faster development of the species as a commercial crop for the mid-Atlantic and fruit belt regions of the United States, where the climate is not a major limiting factor of the species (Lunde et al., 2000; Molnar et al. 2007, 2009 & 2010; Sathuvalli et al., 2010a, b).
|The bristle-covered husk of the non-commercial native beaked hazelnut, Corylus cornuta. Photo: Thomas Molnar.|
Hybrid hazelnuts, which generally are crosses between C. americana and C. avellana, can combine the wide adaptation, cold hardiness, and EFB resistance of the wild American parent, whose native range extends north of Minnesota into southern Canada, with the improved nut quality of commercial cultivars of C. avellana. Improvements made in this hybrid combination can provide a means to grow hazelnuts for production in the Midwest and Upper Midwest regions where cultivars of the pure European species cannot tolerate the cold temperatures. Among the more significant efforts toward adapting hazelnuts to this region to date have been made in Canton, Minnesota, by Philip Rutter (Rutter, 1987), who expanded on breeding work of Carl Weschcke done decades earlier (Weschcke, 1954). Over the past 30 years, many thousands of cold-hardy, EFB-resistant seedlings from Rutter’s breeding efforts have been planted across Minnesota, Wisconsin, and other states in the region, including the nine-acre planting at the National Arbor Day Foundations’ Arbor Day Farm, in Nebraska City, Nebraska. Rutter’s work demonstrates the potential of this sustainable crop for colder regions and has spawned substantial interest in its continued development, study, and application, including investigating its use for biofuel production (Rutter, 2002; Molnar et al., 2005; Hammond, 2006; Xu and Hanna, 2009 & 2010; Braun et. al, 2009 & 2011; Sathuvalli and Mehlenbacher, 2011; Hybrid Hazelnut Consortium; and Midwest Hazelnut Development Initiative).
|Eastern filbert blight-resistant and susceptible plants. Photo: Thomas Molnar.|
Orchard site selection, i.e., soil drainage, slope, fertility buildup, etc., are important considerations before establishing an orchard. Cultivars adapted to the climate of the area along with EFB resistance/tolerance must be selected. Layered, grafted, or micropropagated plants can be obtained from commercial nurseries. Seedling trees can express considerable variation in production traits, including kernel yield, nut and kernel size, kernel percent, disease resistance, etc. Trees are planted in the spring after chance of serious frost has passed. The normal planting rate in Oregon is 109 or 218 trees per acre spaced at 20 or 10 feet, respectively, in the row, with 20 feet between rows. The fertility of the soil should be tested prior to planting and appropriate amounts of lime and nutrients applied according to test results. Once established, weed control will be important until an orchard floor is established. Also important is scouting for insects, diseases, and vertebrate pests. In second and subsequent years, pruning, sucker control, pest management, and additional fertility will be needed. Hazelnuts are harvested mechanically with either airblast or mechanical fingers to sweep orchard floors for immediate pickup. Nuts can then be dried and stored for eventual shelling and oil expelling.
For a full review of planting, maintenance, and harvest details, see Growing Hazelnuts in the Pacific Northwest, EC1219, Oregon State University.
Although hazelnuts have not yet been grown commercially as a biofuel crop, possible oil yields based on the food crops produced in Oregon can be estimated at 90 gal./acre with a potential of up to 125 gal./acre. This figure is calculated based on the 10-year average (1996-2005) yield per acre of in-shell dry nuts in Oregon (2,197 lb/acre [2,463 kg/hectare]) (FAOSTAT) and using the European cultivar ‘Casina’, which has a kernel to shell ratio of 56% and a kernel oil content of 65% by weight. The overall oil yield per acre could be increased through a reduction in the tendency for biannual bearing along with improvements in overall yield, kernel to shell ratio, and kernel oil content through breeding.
|Five-year-old hazelnuts susceptible to eastern filbert blight. Photo: Thomas Molnar.|
The establishment of hazelnut production in the Pacific Northwest, nearly 100 years ago, was largely possible due to being outside the native range of C. americana and its associated pathogen A. anomala, as well as having a climate well suited for cultivars adapted to Mediterranean regions. Unfortunately, this situation changed dramatically with the introduction of EFB in southwest Washington in the late 1960s (Davison and Davidson, 1973). EFB devastated hazelnut orchards in Washington before scientists developed a solid understanding of the pathogen, along with control measures, and plant breeders found genetic resistance to the disease (Johnson et al., 1996; Mehlenbacher and Thompson, 1991; Coyne et al., 1998; Lunde et al., 2000). While little is left of the hazelnut industry in Washington, commercial production continues in the Willamette Valley of Oregon but not without expensive fungicide applications and disease management protocols. Fortunately, after nearly 30 years of breeding, EFB-resistant hazelnut cultivars are now available for use by Oregon growers, and the industry is currently in a state of expansion after many years of decline (Mehlenbacher et al., 2007, 2008, 2009, & 2010). Unfortunately, these EFB-resistant cultivars may not be reliably productive in the harsher climate of the northeastern United States, although most have been shown to be reasonably cold hardy and productive in field trials in New Jersey.
|Eastern filbert blight lesions. Photo: Thomas Molnar.|
Over the past 14 years, work at Rutgers has led to the development and identification of improved, disease-resistant selections of Corylus avellana, as well as advanced generation-interspecific hybrids with C. americana and C. colurna that produce large, high-quality nuts with round kernels over 1.0 gram in size and a kernel-to-shell ratio of over 50%. These plants are products of collaborative breeding efforts between Rutgers and Oregon State University, which has had an ongoing hazelnut genetic improvement program since the late 1960s (Thompson et al., 1996). Starting in 2010, these experimental selections were asexually propagated and planted in replicated yield trials in New Jersey, New York, Pennsylvania, Nebraska, and Ontario, Canada, for evaluation of their crop potential and usefulness for food kernels and/or oil production in low-input farming situations.
Beyond addressing the crop suitability characteristics noted above, hazelnut growers must obtain equipment not generally available on grain, forage, or other traditional farms. Planting and particularly harvesting equipment is needed for production, while shellers and expellers must be accessible for processing the crop and producing oil.
|Eastern filbert blight-resistant hazelnut seedling selection at Rutgers University. Photo: Thomas Molnar.|
Estimated Production Costs
Hazelnuts have not been produced previously on a commercial scale for biofuel, but Oregon State has published Orchard Economics: The cost and returns of establishing and producing hazelnuts in the Willamette Valley, a full report that can assist the reader in assessing economic considerations. In brief, that study estimated total costs (fixed and variable) for full production years at just over $2,800/A. At projected yields of 2,800 lb/A, prices would need to exceed $1.00/lb to result in a profit. A yield of 2,800 pounds would produce a little more than 100 gallons of oil per acre. At current diesel fuel prices, even including the potential value of the meal, hazelnuts would be more profitable as a food crop than a biofuel crop, and not as competitive as some of the other current U.S. oil crops.
Environmental and Sustainability Issues
Once newly adapted, disease-resistant cultivars are available and then established as a perennial tree crop, few environmental impacts should be of concern, and hazelnuts should be one of the easier crops to sustain.
|Eastern filbert blight-resistant hazelnut seedling selection at Rutgers University. Photo: Thomas Molnar.|
Hazelnuts have the potential to produce twice the amount of oil per acre as soybeans without annual planting costs. However, eastern filbert blight and climatic adaptation of current European hazelnuts cultivars have limited production primarily to Oregon.
But, new selections of hazelnuts show few pest or disease problems and thus require greatly reduced pesticide applications compared to most other tree and vegetable crops. Therefore, hazelnuts should be able to be grown in the northeast fruit belt region and beyond, when considering the use of hybrid plant material. In addition, hazelnuts can be grown on sloping and rocky land not ideal for annual crops. Once established, they require little to no supplemental irrigation in many regions. As such, hazelnuts appear to be a potentially ideal candidate for low-input, possibly organic, production. However, further research is needed to determine the best utilization of this crop, considering that the future of hazelnuts as a biofuel may be limited due to their higher economic potential as a food crop.
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Additional Topics on Oilseeds and Biodiesel Production
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