D. Epidermis netted veins
vascular rings
Answer:
the rate at which soil bacteria perform nitrogen fixation
Explanation:
Plants cannot use nitrogen in the air directly as nitrogen present in the air cannot react with other compounds. Nitrogen present in the air is converted into ammonia so that the plants can utilize it. The nitrogen-fixing bacteria convert the atmospheric nitrogen into ammonia.
<em>When the same crop is grown again and again on a soil, the resources become depleted in the soil. Also, the number of nitrogen-fixing bacteria decreases. </em>
Hence, it is essential to practice crop rotation.
