1. Nitrogen Information N By: Becky McGuire

2. Key Facts a. N is in every plant cell b. N is 78% of atmosphere c. Production of N comes from ammonia (NH3) NH3 = atmospheric N + H d. N fertilizer forms = urea, ammonium nitrate, anhydrous ammonia, N solution (28%)

3. N & Soil a. N is very mobile in soil (it can leach from soil easily) b. N losses: 1. used by plant 2. leaching (“draining” from soil) 3. erosion 4. denitrification 5. volatilization

4. Nitrification a. N must be in a from usable by plants b. Ammonium (NH4+), from OM or fertilizers is converted to NO3- (nitrate) c. Carried out by bacteria in soil N must be in nitrate form to be absorbed by plants

5. Leaching a. nitrates are not tightly held by clay and humus (OM) b. can move with soil water c. losses great in sandy, coarse texture soil

6. Denitrification bacteria converting nitrate to elemental (N2) nitrogen which is then lost to the atmosphere a. occurs under anaerobic conditions b. anaerobic conditions occur when soil pores are filled with water and not air (heavy rain) c. Nitrate losses are 15-30% of total applied N when area is flooded for 3-5 days

7. Volatilization : urea is converted to unusable form when applied on warm, moist soils. N lost to atomosphere. inject N to eliminate problem

8. Nitrogen fixation N must be removed from atmosphere to be used by plants a. N fixation: legumes (beans, alfalfa) are able to “fix” N. b. legumes have bacteria (rhizobia) on roots (in nodules) which remove N from the atomosphere. c. Legumes are able to provide own N and don’t need N fertilizer

9. Nitrogen cycle a. atmospheric N converted to usable N (nitrates) then converted back to atmospheric N (N2)

10. sources of usable N --N fertilizers --animal waste --legumes --lightening, precipitation --crop residue

11. Ways nitrates are lost --leaching, erosion, gas, plant use