Soil salinity is measured by

If a plant material is dried and burnt in a crucible,the residue would contain

The transfer of minerals from top soil to sub soil through soil water is called

If a dried leaf is taken in a crucible and heated to $600^{\circ}C$,a gray-coloured powder is left behind. It is referred to as:

What is the correct unit for measuring nutrients in hydroponics nutrient solution?

Humus is important for plant growth because