ASCI 223 - Lab 4 - Grazing Management

ASCI 223 - Lab 4 - Grazing Management - Grazing Management...

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Grazing Management Grazing is the meeting of animal and plant. Sheep, cattle, and horses graze, but so to do antelope, bison, deer, and other large ungulates, and so to do insects, rodents, and other living organisms. Through grazing, stored nutrients are being passed from one trophic level to the next. Grazing management implies that humans are controlling the grazing of the grazers for some specific purposes. Within the livestock sector, the historic use of grazing management was to maximize pounds of product produced for sale. However, in more recent and progressive times, we understand that we must also manage grazing to maintain the very soil health that we need to provide long term production of food and fiber for our livestock as well as all the other herbivores in our environment. To better understand grazing management, one must first understand the basic ecosystem processes that are constantly functioning to cause plants to grow. These four processes are called solar energy flow, the water cycle, the mineral cycle, and community dynamics. Solar energy flows constantly from the sun. Some of that energy is absorbed in the various layers of our atmosphere, some strikes surfaces where it is either absorbed and produces heat or is reflected as heat energy back into the atmosphere. A relatively small part (`10%) is actually taken in by plants during the process of photosynthesis. Solar energy never gets back to the sun – so this process is referred to as “flow” rather than “cycle”. Photosynthesis requires water, carbon dioxide, and chlorophyll and will then produce sugar and oxygen. It is this sugar that provides the grazer with nutrition, and it is the oxygen which allows us to breathe. A key to increased production of sugar and oxygen, which therefore support more life at higher trophic levels, is to increase solar energy collected at the soil surface. This can be done in three ways. First, a manager can increase the plant density (more plants per unit area. Second, a manager can cause more broad leafed plants to grow, therefore producing more photosynthetic surface area per acre. Third, producers can manage to have plants that stay photosynthetically active for longer periods of the year. In this case, having perennial plants is superior to having annual plants which tend to have relatively short growing seasons. In truth, grazing livestock operators are in the solar energy collection business and not the meat production business. Most of you are familiar with the water cycle as it has been presented to you in texts and other sources throughout your education. From that you know that water resides in large bodies of water, is evaporated, it moves over land and condenses, which then ends up at the land surface as precipitation. From there, it can be absorbed into the soil or it runs off the top back into creeks, rivers, ponds, lakes, and finally the oceans. Water also moves through plant roots up through the stems and is released as transpiration. In California, it
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This lab report was uploaded on 04/09/2008 for the course ASCI 223 taught by Professor Rutherford during the Winter '08 term at Cal Poly.

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ASCI 223 - Lab 4 - Grazing Management - Grazing Management...

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