How can you explain the fact that in different plants the roots penetrate into the soil to different depths?

Each plant is different and different, so each plant needs different nutrients and different amounts. The root system of plants has adapted to its requirements, this can explain such a variety of the structure of the roots and the degree of their growth in the depth of the soil. Another difference in root growth can be explained by different natural environmental conditions: soil composition (stony, etc.), the degree of swampiness of the area, the strength of the winds, the climatic zone and the composition of the air.