Step 1: Understanding the Concept
Nitrates are soluble and are not held by soil particles.
They are lost from the upper soil layer by being washed down with water.
Step 2: Check the Biochemical Terms
Amination, amidation and transamination are reactions of amino acid formation inside plants.
They do not move nitrates in soil.
Step 3: Select the Option
Sedimentation is the only option that describes movement or settling of material through soil and water.
So it is the choice given for the loss of nitrates.
Final Answer:
Sedimentation is the choice that describes the loss of soil nitrates.
\[ \boxed{\text{(D) }\text{sedimentation}} \]