Nitrogen is one of the most important nutrients for plants because it is almost always in short supply. The amount of nitrogen available controls plant growth.
Synthetic fertilizer usually supplies nitrogen as urea or nitrate. Organic fertilizer supplies it as proteins and amino acids, and they claim these forms are better for plants. Which forms of nitrogen can plants use, and which is the best form for gardeners to use for growing plants?

Key Takeaways
- Nitrate and ammonium are the main forms of nitrogen used by plants.
- Plants can use urea and amino acids directly.
- Plants also seem to be able to digest proteins and then absorb them through roots, probably as amino acids.
- Organic gardening techniques don’t seem to significantly alter the amino acids in soil.








