Nitrogen cycle

• The role of bacteria in the nitrogen cycle is to convert nitrogen from the air into nitrates in the soil, which are then absorbed by plants then animals
• Farmers increase the amount of nitrate available for plants to absorb by growing the same crops on a field for a few years, as the soil runs out of nutrients.
• The atmosphere is around 78% nitrogen, but plants cannot absorb nitrogen directly from the atmosphere.
• Nitrogen fixing bacteria, also known as nitrogen-fixing bacteria, are found in the soil, some types of plants, and in the roots of certain plants such as peas, beans, and clover.
• Nitrogen fixing bacteria convert nitrogen in the air into nitrates in the soil, which are then absorbed by plants.
• In the first stage of the nitrogen cycle, nitrogen from the air is converted to nitrates by nitrogen fixing bacteria, and the nitrates are then absorbed by plants and animals
• plants and animals die and animals release waste products such as urea where decomposers break down the proteins in both into ammonia
• Decomposing bacteria convert the nitrogen to ammonia in the final stage of the nitrogen cycle, and nitrifying bacteria convert the ammonia to nitrate, which can then be absorbed again by the plants and the cycle continues.
• Some bacteria in the soil breakdown nitrates back to nitrogen gas, which returns to the air, these are called denitrifying bacteria.
• If the soil contains a high level of nitrates, crops grow faster, but over time the level of nitrate in the soil falls as crops absorb it.
• Farmers need to keep a high level of nitrate in the soil, one way of doing this is to add fertilizers such as animal manure or chemical fertilizer like ammonium nitrate.
• Farmers can also use crop rotation, where they grow peas, beans, or clover on their field, as these plants contain nitrogen fixing bacteria in their roots, increasing the level of nitrate in the soil the following year.
• The ammonia is then returned to the soil as nitrates by nitrifying bacteria