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By Dr. Heather Darby, UVM Extension Agronomist
Added September 6, 2010. New England farmers are always searching for innovative solutions to buffer against volatile changes in the price of diesel, heating oil, livestock feed, and fertilizers. Current field-based research is indicating that local farmers have a significant opportunity to produce more of their own liquid fuel, livestock feed, and other high value co-products through oilseed crop production in a crop rotation that is compatible with forage production.
Oilseed Crop Production
Oilseed crops that are most suitable for fuel production and the local climate include sunflower, canola, soybean, and mustard. The National Renewable Energy Lab reports that both canola and sunflower seeds contain 40% oil and soybeans contain 18% oil.
Sunflower and soybean are warm season crops that require a growing season that spans from late May until October. Canola and mustard are both cool season crops that are planted in April and harvested in August. Organic soybean seed is available but sunflower, canola, and mustard can primarily be sourced as untreated seed.
Local oilseed yields from these crops have ranged between 1000 and 4000 lbs per acre. Of course this depends on variety selection, fertility, disease management, crop rotation, and experience. Once harvested the oilseeds should be dried and stored between 7 and 12% moisture. This will keep the seed from heating and also improve oil extraction rates.
Additional local research is being conducted in the area of fertility management, weed control, and other agronomic practices. More information on UVM Extension oilseed trials can be found at www.uvm.edu/extension/cropsoil.
Once the seed is in the bin it is ready to go through the extrusion process. This will require an oilseed press. Locally owned presses range greatly in size, capacity, and cost. The Chinese manufactured oilseed press can be purchased relatively cheaply ($2,000 - $5,000) but requires some modification upon arrival in the United States. Based on farmer experience this press also requires the most oversight during pressing and hence increases labor costs. European designed presses (Tabby and Kern Kraft) are more expensive ($8,000 - $25,000), handle less volume but are more automated. All the presses are equally effective at extruding oil with an average of 35% oil removal from locally produced seed. This means that 2000 lbs of sunflower seed will produce 94 gallons of oil.
Once the oil is extracted the next step is to produce biodiesel. The biodiesel itself is produced from the reaction between alcohol and the triglycerides present in plant oils to produce biodiesel with glycerin being a byproduct. This reaction is catalyzed by sodium hydroxide. The production of biodiesel requires more than just the ingredients themselves. Production of the fuel is a chemical reaction and can be explosive if mistakes are made during the process. Therefore, proper training, standard operating procedures, and safety precautions should be in place on the farm. Some farms have designed their own fuel producing systems. However, many farms have also opted to purchase biodiesel production kits that range in price from $3,000 to $20,000 depending on fuel volume and other features. High quality fuel is being produced and most farmers are simply using homegrown fuel in place of purchased diesel without any modification to equipment.
In addition, to the fuel obtained from oilseeds the meal left over after extrusion has a high value as a livestock feed or even fertilizer source.
Oilseed meals are commonly added to ruminant diets as a supplemental protein source. These feeds are generally 30-40% protein content. Farm produced meal has differed slightly from purchased products (Table 1). The farm grown meal is generally lower in crude protein and higher in crude fat as compared to the purchased meal. Commercial oil extraction is conducted through a solvent extraction procedure. Hexane is the most commonly used solvent because it is highly effective at extracting the oil (nearly 100%). On a local scale, farmers are extracting oil with mechanical expellers. This is a cheaper and safer means to oil extraction but a much less efficient means to removing oil from the seed.
Many farmers have been feeding local meal to a variety of livestock with no adverse impacts. A recent feeding trial was conducted in Vermont to evaluate how the homegrown canola meal impacts milk quantity and quality. The impact of farm grown canola meal on milk yield and quality is shown in Table 2. Overall, cows fed farm grown canola did not differ statistically in milk yield or quality than when fed purchased canola meal. Although not statistically significant, there was a small decline in milk fat content as a result of feeding farm grown canola. Diets with high fat content can often lead to suppressed milk fat content.
There is a potential market for the oilseed meal to also be used for fertilizer. Because oilseeds are high in protein, they contain organic nitrogen. Table 3 illustrates the nutrient content of local oilseed meal.
Recent research conducted in Vermont indicated that oilseed meals applied at 3 tons/acre could supply nitrogen and other nutrients for a corn crop (Table 4). Soil nitrate levels above 25 ppm can support a 25 ton/acre corn silage crop. Interestingly, the sunflower meal released nitrogen at a slower rate most likely due to the high lignin content of the hull.
In addition to their fertilizer value, meals from brassica crops have unique properties that can suppress weeds. The study conducted at UVM indicated that mustard meal was most effective at suppressing weeds.
*Within each column, numbers followed by the same letter are not significantly different.
Additional research needs to be conducted to determine proper oilseed meal application rates that will meet crop nutrient demands while minimizing negative impacts on the crop.
Given the entire picture of on-farm fuel, feed, and fertilizer production there is reason to believe this system would improve farm viability. Although UVM Extension is still investigating the economic feasibility of on-farm fuel production, data collected from one farm calculated the cost to produce biofuel at $1.85 per gallon. The ability for farmers to produce their own fuel represents a number of advantages. First, it gives them a crop the value of which is directly tied to the cost of petroleum. For most farmers the cost of fuel has increased much more rapidly than the prices they receive for the agricultural commodities they produce. So producing a crop whose value is tied to fuel costs has a real attraction. Second, producing their own fuel, feed, and fertilizer would allow them to better predict and manage their operational expenses. For more information on the UVM biofuel project please visit the website www.uvm.edu/extension/cropsoil.
Posted: to Organic Production on Mon, Sep 6, 2010
Updated: Mon, Sep 6, 2010