Soil test is necessary before the use of chemical fertilizer why

Soil test is necessary not only for phosphorus but also for the other essential elements. By analyzing the soil we can understand the status of different essential elements in soil and from the results we can make the recommended dose for the particular soil.

i'd think it's paralell

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs