Nitrifying bacteria also absorbs ammonia or ammonium. During nitrification, they will strip the ammonium or ammonia of their electrons. All of the compounds, ammonium, nitrite and nitrate are sensitive to leaching and runoff. Leaching is when soil water moves out of and area, and it loses the nutrients dissolved in it. When nitrogen is lost to the air, it is a process called denitrification.
People can also affect the nitrogen cycle by pollution.
Nitrogen containing fertilizers and fossil fuels release pollutants that increase soil acidity. This affects the root absorption of magnesium, calcium, and potassium ions. As a result, the cycle loses more nitrogen.