Most suitable form of N for flooded rice soil is

Answer: Option A

The most suitable form of N for flooded rice soil is Ammonium.
Rice plant depends mainly on its nitrogen upon the decomposition of organic matter under anaerobic conditions and in the early stages of growth takes up nitrogen in the form of ammonia which is the stable form of nitrogen in submerged soils.
The main form of nitrogen (N) taken up by rice roots is shifted from ammonium (NH₄) in flooded paddy soil to nitrate in upland soil.