Proponents of organic farming often begin with moral arguments, and the case for improved and retained soil fertility. Now comes more evidence that organic methods have the advantage of energy efficiency, too. The Land Institute of Salina, Kansas, has just published a study that measured, recorded and analyzed every input and output of energy of a 150-acre farm over the course of five years in the 1990’s. The original effort was intended to track and improve the farm’s sustainability, but this close accounting was also able to show that organic farming is in many areas more energy-efficient than conventional, chemical-based farming, even when the increased need for human labor is taken into account.
The study’s authors say they have included significant factors not measured in previous studies of farm efficiency, including supplies (whose energy use they found to be 15-27% of the total), equipment depreciation and the commuting energy use of farm workers (34-54% of the allotted labor energy numbers). Certain earlier studies included some of these factors, but none included all of them.
- Beef production at the Kansas farm was almost twice as efficient as feedlot beef
- Egg production (the farm had 50 egg-laying hens) was also almost twice as efficient as battery caged production
- Wheat and sorghum were grown with significantly less energy
On the other side, raising broiler hens, oats and soybeans required higher energy use than conventional farming studies have shown (but see the caveat below). Also, the use of horses proved much less efficient than tractor use, given the amount of energy needed to grow the animals’ feed–though the authors point out the horses were underused by this farm, since they ate seven days and worked two. Given current fuel availability, the study finds that the greatest efficiency comes with organic methods used with modern gas-powered equipment. The farm’s methods included no irrigation, no chemicals, and wide use of nitrogen-fixing legumes and green manures for the crops, plus free-ranging chickens and intensive grazing management for the cattle.
Finally, the authors observe that the amount of energy use ignored by previous studies significantly throws off their data, and that measuring this energy would (among other things) “overwhelm the putative greenhouse gas or energy advantages claimed for many crop-based biofuels.” This basic point is one that can’t be made often enough: that some scientific arguments on energy use are based on data that do not take enough factors into account. If this study accomplishes nothing else but to show us we must think more carefully about less-obvious energy use when computing true energy costs, it has done a lot.