This is a controversial question depending on your belief in Darwins evolution or not. According to Darwin, this is incorrect.
Velocity is an object or somethings speed in a given direction and since this object has been described as 'stationary' so its velocity would be 0 ^^;
They provide the nutrients that producers need.
~ThePirc
Force of gravity implies percolation of water to deeper horizons in the soil.
The type of soil is highly depended on the rate of percolation to take place, this is because the sandy soil dries faster than clayey soil. It also depends on the amount of water which is in the soil reservoir reason being soil becomes unsaturated so the amount of water remaining occurs in a form of a thin film which surrounds the soil particles.