Plan oil by the pressed yield per acre, not by the oil held in the seed: a press recovering 50-70% turns the 280-675 lb of oil held in an acre of sunflower seed into 140-472.5 lb, rapeseed’s 400-880 lb into 200-616 lb, and flax’s 140-360 lb into 70-252 lb. Supplying a village’s 1,100-2,200 lb a year then takes 2.3 to 15.7 acres of sunflower, 1.8 to 11 of rapeseed or 4.4 to 31 of flax.
Part of Oil Pressing at Scale
Oil per acre for each crop, from seed yield, oil content and press recovery, with the acreage a village of 100 needs and a reconciliation of the different yield figures in the wiki.
Three Multipliers Turn An Acre Into Oil
Oil per acre is seed per acre times oil fraction times the fraction the press recovers. The carrier’s figures stop after the second multiplier. Seed yields and oil contents are the carrier’s; recovery is the corpus’s 50-70% for simple presses (Oil Extraction, Seed Pressing).
| Crop | Seed (lb/acre) | Oil fraction | Oil in seed (lb) | Pressed at 50-70% (lb) | US gallons |
|---|---|---|---|---|---|
| Sunflower | 800-1,500 | 0.35-0.45 | 280-675 | 140-472.5 | 18-62 |
| Rapeseed | 1,000-2,000 | 0.40-0.44 | 400-880 | 200-616 | 26-80 |
| Flax | 400-800 | 0.35-0.45 | 140-360 | 70-252 | 9-33 |
Working, sunflower: 800 x 0.35 = 280 lb and 1,500 x 0.45 = 675 lb in the seed; pressed 280 x 0.5 = 140 lb and 675 x 0.7 = 472.5 lb. Gallons use 7.68 lb per US gallon (0.92 kg/L x 3.785 L x 2.2046 lb/kg); the carrier’s own conversion works out near 8 lb a gallon, so it is a US gallon, not an imperial one (which is larger).
Olive Is Counted By The Tree
The carrier gives 20-50 lb of oil per mature tree. A year’s 1,100-2,200 lb needs 1,100 / 50 = 22 to 2,200 / 20 = 110 trees, bearing from 5-12 years after planting.
Acres For A Village Of 100
At the carrier’s budget of 1,100-2,200 lb of cooking oil a year (Community Oil Budget), the acres are the oil needed divided by the pressed yield per acre, best case to worst:
| Crop | Best (high yield) | Worst (low yield) |
|---|---|---|
| Sunflower | 1,100 / 472.5 = 2.3 acres | 2,200 / 140 = 15.7 acres |
| Rapeseed | 1,100 / 616 = 1.8 acres | 2,200 / 200 = 11 acres |
| Flax | 1,100 / 252 = 4.4 acres | 2,200 / 70 = 31 acres |
The carrier’s 3-8 acres for sunflower sits at the favourable end of the 2.3-15.7 range. Plan from your own measured yield, which will fall somewhere inside it.
Reconciling The Wiki’s Different Sunflower Figures
Per hectare (1 gallon per acre is 3.785 / 0.4047 = 9.35 L/ha):
| Source | Gallons/acre | L/ha |
|---|---|---|
| Carrier, oil in the seed | 35-85 | 327-795 |
| This article, carrier seed yield pressed at 50-70% | 18-62 | 170-575 |
| Chemistry page, hand-worked, lower seed yields | 13-46 | 122-426 |
The three differ because each applies more of the real losses. The carrier assumes the press takes all the oil. This article applies the press loss. The chemistry page also uses lower seed yields (500-1,000 lb an acre from the caloric guide), which is why its oil is lower again (Oilseed Crops). A village that has not yet measured its seed weight should plan for the lowest of the three.
What You Need
- A measured plot of a few square metres of each crop
- A scale, to weigh the dried, cleaned seed from the plot
- A press that has been run on a weighed batch, so recovery is known
Method: Measure Your Own
Step 1: Weigh the dried seed from a measured plot. Say 1.2 kg from 10 m2.
Step 2: Convert to a yield per acre. 1.2 / 10 = 0.12 kg/m2 = 1,200 kg/ha, and since 1 kg/ha is 0.892 lb/acre, 1,200 x 0.892 = 1,071 lb/acre, inside the carrier’s 800-1,500.
Step 3: Press a weighed batch and compute the recovery (oil out over seed in, divided by oil fraction) as in Processing Steps.
Step 4: Multiply to get pressed oil per acre, and divide the oil needed by it.
Common Mistakes
- Quoting the oil in the seed as the yield. The press leaves 30-50% behind.
- Mixing US and imperial gallons. The conversion factor differs by about 20%.
- Planting to the best case. Plan for the middle, and keep the margin as land.
Oil crops and combustible dust
Seed dust and press cake are combustible; keep open flame out of the pressing and drying areas, and never test for dust with a flame. Cake stored damp heats itself.
What’s Next
- Learn next: Community Oil Budget - the demand side
- Combine with: Crop Calorie Yields per Acre - land for oil against land for food