The general rule of thumb is that it takes about 40 gallons (150 liters) of sap from sugar maples of the Vermont variety to make one gallon (3.8 liters) of syrup, Hegarty said. For red maples, you need at least 60 gallons (more than 225 liters) of sap because more water needs to be removed in the process of making syrup.
Holy crap, I knew syrup farming was inefficient but dam getting less than 4 litres out of 150 litres is insane.
edit followup thought: i suppose it is better to have the forrest than another industrial complex.