the upper layer of soil called horizon a is where
Topsoil In soil classification systems, topsoil is known as the "O Horizon or A Horizon," therefore, it is the very top layer.[2]
Alonso Álvarez de Pineda
Vande Mataram Vande Mataram (IAST:
Rate equation k is the first order rate constant, which has units of 1/s or sâˆ’1.