Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
The Nitrogen Cycle Chapter 2 Nitrogen • The circular flow of nitrogen to free gas in the atmosphere (it is 78% of our atmosphere), to nitrogen compounds (such as nitrates) in the soil, back to atmospheric nitrogen. • In it’s elemental form (not a compound), it is a colorless, odorless gas. • It must be combined with oxygen or other elements before it becomes available as a nutrient for living organisms. • Plants and animals use nitrogen compounds to form DNA and proteins and vitamins. Nitrogen Cycle • Nitrogen fixation-a process by which nitrogen gas from the atmosphere is converted to nitrates. • This can happen in several different ways: – Nitrogen-fixing bacteria can convert gas to nitrates. • Some of these bacteria live in the soil, and others live in nodules on the roots of legumes (like beans). – Several industrial processes convert the gas to nitrates. • Ammonia gas (a by-product of steel making) can be converted to nitrates. These nitrates are used as fertilizers. Nitrogen Cycle continued… – Nitrogen fixation also occurs naturally when lightning strikes . – Nitrates are also released when plants and animals decay, or from animal wastes. Nitrogen Cycle continued… • Denitrification is the process where nitrates are broken down and the nitrogen is released back into the atmosphere. – Happens by some bacteria – Also happens when nitrates are carried off by surface water, which constantly exchanges nitrogen with the atmosphere. The Nitrogen Cycle, with pictures and arrows… • Please look at Figure 2-10, on page 27.