One question arising from the articles on Global Warming involved plants capturing energy and carbon dioxide. Since there is unfortunately little to write about regarding the wheat or summer crops with the exception of some rain and moderate temperatures, let’s take a brief look at photosynthesis.
• First a quick definition is in order. Organic is a term used in everything from news stories to the grocery store to denote “natural”. In reality the definition of organic is quite simple. Organic in chemical terms denotes compounds with carbon atoms in them. Life here, including us, is carbon based so we tend to think of organic as a synonym for life.
• The source of energy for the Earth is the sun. This energy is in the form of electromagnetic radiation – light. While we can see and feel the effects of this energy, we cannot use it directly to maintain our bodies.
• Without photosynthesis, there wouldn’t be life as we know it. While there are other autotrophs, organisms capable of making organic molecules from inorganic sources, plants are what most life on Earth relies on to survive. Why?
• Plants, and certain other organism, have the ability to convert radiant energy to readily useable chemical energy through photosynthesis. Not only can they convert this energy but they produce compounds that can be transported, used as building blocks, or stored for future use.
• Photosynthesis consists of two reactions. The light reaction followed by the dark reaction.
• In the light reaction sunlight, primarily red and blue light, is absorbed by chlorophyll and stored as chemical energy by creating bonds through the formation of ATP and NADPH. These two energy carrier molecules are the same as those found in all living organisms.
• The energy stored from the light reaction is then used to create the simple sugar glucose through the dark, or light-independent, reaction. The inputs to create glucose are carbon dioxide and water. Each glucose molecule needs six CO2 molecules. As each molecule of glucose is produced six oxygen molecules are also released.
• Two glucose molecules are added together to form sucrose and adding more sugars creates more complex organic molecules. This simple sugar is the building block for more complex sugars, starch, and cellulose.
• These sugar-based compounds also supply the energy for cells to maintain themselves through aerobic respiration. Essentially this is the reverse of photosynthesis. Sugar is combined with oxygen to capture energy as the bonds are broken in the forms of ATP and NADPH with CO2 and water as byproducts.
• This is why fossil fuels are valuable energy sources. The energy captured in organic molecules found in coal, oil, and natural gas is released upon burning. As these organic molecules are broken down (oxidized) they release CO2.
What this means for agriculture – no matter where or what – is that in a nutshell all producers do is capture solar energy in chemical form.