Column by John Mattingly
Agriculture – August 2008 – Colorado Central Magazine
AS A FARMER, I’ve always viewed my ground as a solar collector. No matter how hard I appear to work — and like many of my cohorts, I’ve done little to refute exaggerations of my toil — the sun does most of the heavy lifting in the growth of a crop. This is often neglected when farmers and gardeners (and their attending hosts of fertility suppliers) talk about production yields.
Before sizing the role of the farmer or gardener in the success of a crop, three solar basics should be considered:
1. The Solar Heat Units (SHUs) received during the relevant growing season present the most important variable in production success. Yet this factor is almost never noted.
The SHU for a given crop is calculated by adding the high and low temperatures during the 24 hours from midnight to midnight each day of the growing season, and then subtracting from that sum the Basal Developmental Temperature (BDT) for a given crop. Corn, for example, has a BDT of 50 degrees, while the BDT for peas is 40 degrees. Corn is thus considered a warm weather crop that thrives on heat, while peas are considered a cool weather crop.
Keeping a record of the SHUs for a given crop is a much better indicator of development and vigor than calendar time alone. For example, when seed packets indicate a crop is a 90-day crop, this does not mean 90 calendar days. It means 90 days in which the minimum BDT is met. A 90-day corn variety, for example, could take 120 calendar days to mature above 7,000 feet, but only 80 days in Iowa.
2. Timing of rainfall relates to solar activity, as the sun is the prime mover of global air and hydro cycles. Average rainfall data doesn’t address the critical function of timing. Two inches of rain on a sprouted crop is very different from that same rainfall at jointing, flowering, pollination, or any other critical growth stage of a plant. In the San Luis Valley, there’s an old joke: “We get 7 inches of rain a year, and you don’t want to be here the day we get it.” A cloudburst on a ripe crop often spells its ruin, while that same outpouring at an earlier stage could mean a bumper crop.
3. Frost. In high altitude farming and gardening, it’s essential to weigh in with the timing of the first and last killing frost of the season, and the distribution of SHUs in relation to those frosts. In a year when there is a late spring frost followed by lots of heat units, there often is an increase in the vigor of a crop, the frost causing better root development and broader tillering. On the other hand, a frost-free spring that gives a crop a surprising jump on development can be followed by an early fall frost that reduces the bounty of harvest, sometimes to nothing.
DESPITE THE FUNDAMENTAL significance of these three solar-based factors, farmers typically talk about their yields referencing fertilizer, seed genetics, and tillage programs. While these are significant, they really should be placed in proper perspective, although I fully understand why farmers take after Claudius Ptolemy and see themselves as central to all the celestial action around them. When you spend the season working with a crop, it’s easy to confuse the forces and factors you control as a grower with those you simply witness. Standing before a handsome crop you planted and nurtured, there’s a natural tendency to take more credit than is due. Interestingly, though, when solar forces, (aka Mother Nature and all her vernaculars) destroy a crop, farmers place the blame where it belongs, thus acknowledging the power of the sun in the failure of a crop more readily than in a bountiful harvest.
On the flip side from those paying attention to solar basics and sound human management are those peddling the agricultural equivalent of snake oil, obesity powder, toothache wax, and wisdom cream, also known as soil amendments, microbe multipliers, plant stimulants, and humus builders. The people selling these products often provide stunning testimonials about production successes with their product, but I have never seen any real evidence of their yield advantages expressed in the context of the three basic variables discussed above, nor has any local experiment station been able to confirm claims made by the product promoters in the context of sound human management strategies.
Yes, so-and-so down the road sprayed his crop with this product (in one case, I researched the product and found it to be the urine of pregnant donkeys mixed with horse manure) and so-and-so cut a bumper crop. But this sales pitch violates the principle that correlation is not causation, and also the logical fallacy known as an undistributed middle, which is sometimes expressed as: a rose is red, an apple is red, and therefore a rose is an apple.
In the years I farmed, at least one fertility barker knocked on my door every spring. I evolved a response that I believe justly challenged them. First I told them my pattern for analyzing production success began with the three solar variables discussed above. Second, I gave them a map of my farm fields and told them to apply their product to a test strip for three consecutive years, but not tell me where they did it. If the test strip in fact increased crop yield, I should see it, and after three consecutive years of seeing a result, I could isolate their product’s effectiveness from the consequence of the relevant variables. Then, presuming their product had proved itself worthy, I would buy it. This deterred most fertility barkers, but their ranks are not shrinking.
Though the number of farmers actually sitting on tractors is declining (something like 2% of the U.S. population), the number of people involved in supplying farmers with products and services is increasing (28%, up from 26% in 2006), which is testament to our undying devotion to food.
Taking a broader view, the natural history of life on Earth can be viewed, at its most fundamental, as a history of the competition between various species for control of the sun.
All species depend on the sun for food, so a species’ potential for both growth in the size of individuals within the species as well as the ultimate size of the species’ population, is limited by the capacity of that species to access solar energy.
Humans did a nifty end-run around the natural limitation on population size by figuring out ways to store solar energy, and perhaps more significantly, ways to harvest stored solar energy in the form of wood, coal, oil, and natural gas. By tapping into storehouses of fossil solar energy, humans have been able to expand their population in ways never attempted by companion, or predecessor, species.
If trees, for example, had figured out how to turn fossil fuels into fertilizer 300 million years ago, Earth would be overrun with colossal forests and our ancestral mammals might never have seen the light of day. Or if the mega-fauna of the Eocene had learned to cultivate grasses, ambitious apes might never have had a reason to walk upright. Or again, imagine the world today if the giant insects of the cretaceous had learned to farm.
Because the supply of ancient solar energy is finite, it’s reasonable to fear that we humans may have expanded our population beyond the tipping point, and to further fear that when the fossil solar energy is exhausted, we may find we’ve sawed off the very branch on which our evolutionary success is perched. On the other hand, most of our success as a species can be attributed to our large brain, to which we have devoted enormous evolutionary energy, giving it about 20% of the calories we consume. If our brain proves worthy of all the solar energy it has captured — that is, if its high energy demand results in a high level of adaptation — there may be more than light at the end of our emptying cornucopia.
John Mattingly was last seen in Creede, promoting an art gallery with a float in the Independence Day parade.
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