Two groups of tomatoes were grown under laboratory conditions, one with humus added to the soil and one a control without humus. the leaves of the plants grown without humus were yellowish (less green) compared with those of the plants grown in the humus-enriched soil. the best explanation for this difference is that

Humus may be defined as the substance present in the soil that are amorphous in nature. Humus helps in maintaining and retention of the nutrients and moisture.

Two tomatoes are grown in the soil. The plants without humus are yellow whereas plants with humus are green in color. This color difference is due to the absence of the particular chemicals in the soil. The humus soil contain important minerals like iron and magnesium that are important for the chlorophyll synthesis. Thus, humus rich soil are green in color.