1
Finally, the _plants _growing in soils are powerful agents of soil formation.
2
The most effective water impurity, considering soil formation, is the gas, _carbon dioxid.
3
The second great chemical agency of soil formation is the oxygen of the air.
4
We have learnt these things about soil formation.
5
While, therefore, the physical agencies of soil formation are most active in arid climates, the same cannot be said of the chemical agencies.