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Agriculture and the Laws of Thermodynamics
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The annual Jack Kilby Science Day was this past Thursday at Barton Community College. High school students from all over the area were exposed to a variety of topics including agriculture. There are many ways to explain what agriculture is and what it entails. While it may seem a little bit out there, agriculture can be described using the first two laws of thermodynamics. First what are these laws, with apologies to physicists, and second how do they relate to production agriculture?
First Law of Thermodynamics: Energy or matter can neither be created nor destroyed but it can change forms. This simply means when the universe started all the energy and matter in the universe today was present. We are neither gaining or losing energy or matter but its form can and does change. All of agriculture is based on this law whether producing food, fiber, fuel, crops, or livestock. The source of energy for life on Earth is the sun.  This is radiant (electromagnetic) radiation. This is the energy providing light and heat for the planet. How does this relate to agriculture?
The matter part may be fairly obvious. Agriculture starts with plants producing vegetative matter and/or seed. This starts by taking carbon dioxide and water and making sugar which is used for energy and as a building block, along with other nutrients for plant parts and tissue. The energy transformation part of the law is the key to agriculture. Animals can’t do anything with sunlight, radiant energy. As people, other than a tan, all we can do with sunlight is synthesize vitamin D so the energy in sunlight is unusable. Plants in agriculture take energy unusable to us (sunlight) and convert it to sugar (usable chemical energy). That is the key to almost all life on earth and essentially what agriculture does.  
Second Law of Thermodynamics: Energy exhibits entropy. It moves away from its source. In this sense, energy or heat cannot flow form a colder body to a hotter body. The universe is constantly losing usable energy and never gaining. Entropy is the measure of the disorder of a system. A highly ordered system has low entropy.
In simple terms water can’t flow uphill unless energy is added to it since water at the top of the hill has more energy than when it reaches the bottom. The universe is slowly winding down to a lower energy state. Energy and matter move from a higher concentration to a lower concentration and never the other way around unless energy is added to push the process the other way. Take a container of water at room temperature and add a few drops of food coloring. Over time the dye will diffuse until the color of the water is uniform. Energy acts the same way. Nature prefers a system to achieve the lowest energy state possible since it is easier to maintain – to reach a stable equilibrium. Everything, unless energy is constantly being added tends toward disorder – a high state of entropy. So first agriculture is in the energy conversion business and second it is in the business of continually fighting entropy (disorder).
Production agriculture, both plant and animal, is in the business of maintaining order – fighting entropy. Production systems aren’t natural as they are well-maintained – to be successful the must exhibit low entropy to produce food, fiber, and fuel. This is why there will always be good, high paying careers in agriculture.  We must continually fight nature and entropy, even if you are an organic producer.  So the next time you think someone views agriculture in less than flattering terms, just tell them agriculture is in the energy and entropy business.