F.A. Farm

  (Ferndale, Washington)
Postmodern Agriculture - Food With Full Attention
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The Calorie Cost of Using Tillers

We don't use tractors for tilling, planting or cultivation. If I need some field mowing done, I hire the neighbor and I spend about $100 per year. My gas costs last year for my tillers was less than $100 and my estimate of actual gallons used was 27.5 gallons. A gallon of gas contains approximately 31,000 calories. [By the way, these are kilocalories, but calories is the usual shorthand used. Some scientists prefer joules, but since calories are understood by nearly everyone as a valid unit of energy produced and consumed, I still use calories. This is science adapting to cultural usage.] Therefore, my tiller gas last year amounted to 852,500 calories (31,000 X 27.5). As a contrast, I estimate I put in 1000 calories per day into the farm out of a total calorie usage of 2500 per day. In other words, I put in 365,000 calories to grow food in 2008. These are gross estimates of course, but I only have this one job and it is my main focus. I do participate in other activities and I do drop 10-15 pounds in the summer each year, so after subtracting 1250 calories for the daily maintenace of my body from my calorie count per day and 250 calories for non-work activities, I feel 1000 calories per day for farm work is a good conservative number. It might be less but probably not more.

I cultivated 2.5 acres last year by hand and with my tillers, so if I contributed 365,000 calories and the tiller gas I used contributed 852,500 calories, the total of just these two energy sources was 1,217,500 calories, or 487,000 calories per acre. Now, based on last year's potato production of 1,998.6# for 1785 row feet, or 4,462.5 sq. ft. (rows are on 2.5 foot centers), I produced the equivalent of .448# of potatoes per square foot, or 19,500# of potatoes per acre. Potatoes are about 350 calories per pound (some say 385 but I will use the lower figure), so that is 6,825,000 calories per acre. If I had produced potatoes, at this rate, on 2.5 acres, I would have had over 17 million calories produced, for a calorie cost of 1.2 million calories. In realistic terms, potatoes form the upper limit on calories produced per acre as they easily produce twice as many calories per wheat per acre. [The usual metric is 6-8 million calories per acre for potatoes and 3-4 million calories per acre for wheat. Diversified vegetable production is always going to be lower than just potatoes, hence potato production as defining the upper limit.]

Here's the bottom line. Potatoes produced at a rate (remember this is a relative rate, not an absolute quantity) of 17 million calories and human+gas inputs at 1.2 million calories equals a 14-to-1 ratio. This is a very nice metric and reinforces my claim that I produce over 10 calories of food for every calorie I put into producing the food. What is new about this analysis is the role of tiller gas. It would be an affront to mathematics to try and isolate the role of the tiller gas vs. human labor, because there is also an interaction between the two variables. In other words, I get a lot of work done because I use a combination of tiller gas and human sweat to drive both engines (the tiller and my body), which are combined into a practical meta-engine of the human behind the tiller. However, I can say this: The most practical alternative right now, at this time in history, is a human using a walk-behind tiller. The gas costs in dollars and calories are low and the human sweat provides an added dimension to the calories produced by the fossil fuels. In the brave new world after petroleum is no longer feasible, it is likely farmers will actually make a fair return on their labor, so I might be able to make a living on only half an acre that I till, plant and cultivate entirely by hand.


How Many People Can We Feed?

The US has quite a bit of arable land still available. Estimates on the Web range from 302 million to 470 million acres. Since I am a sustainable farmer, I know how much food I can grow, how many potential calories are available through human labor, and other parameters for how many people we can actually feed with only minimal use of petroleum products. Let's take the low figure of 302 million acres of arable land. Certainly this includes land which must be irrigated, but there were several traditional cultures that managed to grow food in extremely arid environments and did quite well. One example was the Hohokam in the area now known as Phoenix, Arizona. They had an extensive network of irrigation canals that could conceivably serve as models. There are ways to do irrigation that are relatively low impact and many farmers and environmentalists are advancing this approach. In other words, irrigation should not be a limiting factor in how much arable land can be used for production.

What about labor then? What intensive petroleum use does is allow many more acres to be farmed by fewer people. Yet we have a lot of people that will soon be out of work, if they are not already. One of the "untouchable" subjects in most discussions of transitioning to a saner society is the idea that we will have to dramatically increase the number of people doing manual labor. My estimate is that we will need 10-20% of the population actively working full-time as farmers. So . . . as a farmer, I will have to feed myself and either 4 other people, or feed myself and 9 other people. This is certainly doable as I now produce enough calories on 2 acres to feed approximately 10 people with a daily calorie requirement of 2500 calories.

Is land use and ownership a problem? Yes it is. However, since we are talking inevitability of dieoff unless we act like an aggregate of local communities, I don't see land use as continuing to be as narrowly strait-jacketed as it currently is. In other words, people with land will be forced to realize the benefits of growing food and will have people ready to work the land in labor-intensive, small-scale agriculture. A land of small farmers growing food on postage stamp-size lots is not just a fantasy, but rather the likeliest way that the future will develop, given the lack of leadership from government, coupled with the intransigence of public employees (elected or not) to do anything without extreme prodding.

To sum up, how much food can we grow on 300 million acres of arable land? I suggest we can feed 1.5 billion (300 million acres X 5 people per acre). Many of you old fogey types (and even some of you "new" fogey types) will scoff, but I suggest we can actually feed the world via small-scale intensive agriculture. When oil was cheap, millions were starving because of inadequate world-wide distribution and corporate greed. I suggest that the future starving millions will still be the result of inadequate world-wide distribution and corporate greed, NOT because we cannot raise the food without cheap oil.

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