Session
2025 Session 1
Location
Brigham Young University Engineering Building, Provo, UT
Start Date
5-5-2025 9:30 AM
Description
Nitrogen (N) recycling is essential in closed root-zones for bioregenerative life support in crewed missions. Microorganisms recycle organic N forms from human waste into ammonium and nitrate for plant growth. We used lettuce as a model crop to examine yield under multiple N sources modelled from N recycling. Plants were grown in peat moss media adjusted to pH 6 or 7 for five repeated plantings in the same containers without replacing the media. A nutrient solution was used for both studies that contained N as either ammonium nitrate, ammonium, nitrate, urea, or microbial biomass from the N-fixing microorganism Azotobacter vinelandii. Plants grown with N from ammonium, urea, or microbial biomass had reduced yields during the first planting compared to the other treatments, but this yield discrepancy diminished in following plantings. Plants grown in containers receiving ammonium nitrate tended to have the most stable yield overtime. These results demonstrate that lettuce yield is improved with a mixture of N forms, and that sufficient microbial communities must develop before nitrification is established.
Nitrogen Form Determines Lettuce Yield in Continually Replanted Systems
Brigham Young University Engineering Building, Provo, UT
Nitrogen (N) recycling is essential in closed root-zones for bioregenerative life support in crewed missions. Microorganisms recycle organic N forms from human waste into ammonium and nitrate for plant growth. We used lettuce as a model crop to examine yield under multiple N sources modelled from N recycling. Plants were grown in peat moss media adjusted to pH 6 or 7 for five repeated plantings in the same containers without replacing the media. A nutrient solution was used for both studies that contained N as either ammonium nitrate, ammonium, nitrate, urea, or microbial biomass from the N-fixing microorganism Azotobacter vinelandii. Plants grown with N from ammonium, urea, or microbial biomass had reduced yields during the first planting compared to the other treatments, but this yield discrepancy diminished in following plantings. Plants grown in containers receiving ammonium nitrate tended to have the most stable yield overtime. These results demonstrate that lettuce yield is improved with a mixture of N forms, and that sufficient microbial communities must develop before nitrification is established.