Sweet sorghum yields 100-200 gallons of syrup an acre, which weighs about 1,150-2,300 lb and carries about 1.5-3.0 million kcal, so a community that wanted 200-500 lb of sweetener from it would need only about 0.12-0.58 acre. The sugar guide gives no labour figures, so the effort has to be measured in your first season, and the largest single task is the evaporator and its wood.
Sorghum yield and labour requirements are the syrup produced per acre of sweet sorghum and the work of growing, pressing and boiling that it takes.
What The Acre Gives
The sugar guide’s yield is 100-200 gallons of syrup per acre under good conditions. Density and energy values are recalled: sorghum syrup about 1.38 kg per litre and about 290 kcal per 100 g.
Worked Example: Weight, Energy And Acres
- A US gallon of syrup weighs 3.785 × 1.38 = 5.22 kg, about 11.5 lb.
- An acre at 100 gallons: 522 kg, about 1,150 lb; at 200 gallons: 1,045 kg, about 2,300 lb.
- Energy: 5,223 g per gallon × 2.9 kcal per g = 15,150 kcal a gallon, so 100 gallons is 1.51 million kcal and 200 gallons is 3.03 million kcal, about 1.5-3.0 million. The caloric guide’s staple crops range from 0.9 to 5.25 million kcal per acre, so sorghum syrup sits in the middle of that range, although it carries almost no protein.
- Land for a sweetener target: the sugar guide’s honey target for a community of 100 is 200-500 lb. If sorghum syrup replaced it, taking the syrup as about 75% sugars by weight (an assumed value), that is 200 ÷ 0.75 = 267 lb to 500 ÷ 0.75 = 667 lb of syrup. At 11.5 lb a gallon that is 23-58 gallons.
- Acres = gallons ÷ yield: 23 ÷ 200 = 0.12 acre in the best case, and 58 ÷ 100 = 0.58 acre in the worst.
- Per person: 23-58 gallons for 100 people is 0.23-0.58 gallon each.
The comparison with beets in the sugar guide is therefore not a clear advantage once the beet yield is derived correctly (Yield per Acre).
What The Land Is No Longer Doing
An acre of sorghum is not an acre of grain, beans or roots, and a plot of 0.12-0.58 acre is small next to the caloric guide’s 51-68 acres of food crops for 100 people. The pressed stalks feed animals, which recovers some of the value (Livestock Feed Conversion).
Labour: What Is Known And What Is Not
The guide gives no hours for any stage. The tasks are: sowing and weeding; cutting, stripping and hauling stalks; pressing; hauling and splitting wood; tending the evaporator and skimming; filtering and jarring. The pressing page shows the juice volume: at an assumed 15% sugar, 676-1,353 gallons for 100-200 gallons of syrup, and 1.35-5.4 tonnes of wood per acre (Pressing and Boiling), which gives a sense of the scale of the hauling and the firing, but not the hours. Record person-hours for each task in the first season, per gallon of syrup, and use them to plan.
What You Need
- A measured plot and a stalk-weight sample
- A time log for each task
- A press and a pan sized to your juice volume
- A wood supply (Coppicing Fuel Management)
Method: Plan Acres And Effort
Step 1: Set the sweetener target in pounds. Step 2: Convert to gallons of syrup using your syrup’s weight per gallon. Step 3: Divide by your measured gallons per acre. Step 4: Estimate juice volume and wood, then record the real hours. Step 5: Compare labour per gallon with maple and honey, and keep the cheapest sweetener that your climate allows.
Common Mistakes
- Using the 100-200 gallon yield without a trial. Your soil and season differ.
- Counting syrup weight as sugar weight. Syrup contains water.
- Ignoring fuel and labour. The evaporator sets the working rate.
Safety
Fatigue near a boiling pan
Long evaporator shifts in the cold or heat, carrying wood and juice, are the setting for scalds and falls. Work in rotation, keep the walkway clear, and keep burns under cool running water at once (Thermal Injury Care).
What’s Next
- Learn next: Shelf Life of Sweeteners — storing the harvest
- Combine with: Caloric and Nutritional Role — what the syrup is worth