Biogeochemical Cycles and Our Plants

Last week, we planted our little seedlings - not so long ago only seeds- and prepared them for a week of growing and experience in the outside world. When we visited them again today, there was a very clear difference: their size. They have already grown at least 2 inches taller than they were when they were first planted, and the leaves have also grown immensely, with our largest plant having leaves of a 5 inch length and 3.5 inch width. Also, their color is a different green, a more muted medium green color than the bright green sprouts of last week. The last main difference was the tiny holes in some of the leaves, most likely made by little bugs.

Our plants use water in many ways, and are a great part of the water cycle. One way they take part in the water cycle is in evaporation through transpiration. Transpiration is when plants lose water through their leaves. When the evaporated water condenses, precipitation eventually occurs when the water falls back onto the plants and land. The plants use this water in photosynthesis so they can grow. From there, the water evaporates once again. Some of the changes that I could see related to the water cycle. A couple of the plants looked slightly dried out. The other two were the opposite; a lively, fresh bright green. I think this was because of their role in the water cycle. The plants with the dehydrated leaves needed more water, and maybe had gone through transpiration very recently. The other plants were healthy and strong, which let them absorb more water.

    Carbon makes up all living things, and given that our plants are living, carbon is in them too. In the carbon cycle, there is carbon dioxide in the atmosphere that plants and animals take in, and when they die and are buried, that carbon is turned into fossil fuels. These fuels are then burned by humans, releasing carbon into the atmosphere once again. Our plants use carbon dioxide to grow and get energy. When I notice that my plants are bigger, they are being part of the carbon cycle. At the same time, when I take note of the plant that has the most holes, I can see that when it dies its carbon will go into the ground.

    The nitrogen cycle is similar to the carbon cycle in the realm of our plants. Our plants use nitrogen in the form of ammonium in the soil as well as in the atmosphere and rainwater. The nitrogen lets them grow and live, and when they die the organic nitrogen is returned to the earth through decay. I know that some farmers use fertilizers with nitrogen to get their plants to grow better. When I see the plants growing in healthy soil, I know that means there is a form of nitrogen in the soil and in the plants.