Which of the following characteristics is not true of alluvial soils?

Alluvial soils are not generally rich in phosphorus but poor in potash. The alluvial soils are generally rich in potash but poor in phosphorous. In the Upper and Middle Ganga plain, two different types of alluvial soils have developed, viz. Khadar and Bhangar. Khadar is the new alluvium and is deposited by floods annually, which enriches the soil by depositing fine silts.