Answer:
the humus contains the minerals necessary for chlorophyll synthesis
Step-by-step explanation:
The yellowness of leaves in plants can be attributed to inadequate chlorophyll in the plant. The chlorophyll is responsible for the greenness appearance of the leaves of plants and when it is present in inadequate quantity, the leaves appear yellowish in color.
Some of the minerals necessary for the formation of chlorophyll include magnesium, nitrogen, and iron. It thus means that the humus supplied to the soil of group 1 plant has the necessary minerals to synthesize chlorophyll while the soil of group 2 plants is deficient in some or all the minerals required for chlorophyll synthesis.