Plants growing in acidic soils are known as

Which type of soil has the least water-retaining capacity?

The possible resource of phosphorus ions and nitrogen ions in soil generally get depleted because they are usually found as

Out of the $105$ elements discovered so far,how many have been found in plants?

In hydroponics,a chelating agent is used to

Which element is responsible for causing soil salinity? At what concentration does the soil become saline?