Nitrogen undergoes transformations in the soil depending on the chemical composition of the nitrogen applied. Learn more about Yara at http://www.yara.com/sustainability/cl...

While nitrate is taken up directly by plants, ammonium and urea first need to be transformed into nitrate. Transformation losses are lowest with nitrate and highest with urea. All the nitrogen in the soil, whether it was applied as urea, ammonium or nitrate, ends up as nitrate before plants take it up.

If nitrate is applied directly, then losses from the transformation from urea to ammonium and ammonium to nitrate are avoided.