What are non-mineral nutrients relevant for plants?

Non-mineral nutrients are essential elements for plant growth that do not originate from soil minerals. Carbon (C), oxygen (O), and hydrogen (H) are classified as non-mineral nutrients because they primarily come from the atmosphere and water rather than from soil mineral sources.

Plants acquire carbon dioxide from the air during photosynthesis, oxygen is a byproduct of this process and is also absorbed from the air, and hydrogen is obtained from water. These elements play critical roles in various physiological processes, including energy production and cellular structure formation.

The other options refer to mineral nutrients or are limited to mineral elements. For instance, nitrogen and phosphorus are essential macronutrients but are classified as mineral nutrients because they primarily come from soil and fertilizers. Calcium and magnesium, mentioned in another option, are also considered mineral elements as they primarily derive from soil sources. Thus, focusing on the roles and sources of non-mineral nutrients highlights the significance of carbon, oxygen, and hydrogen in plant nutrition.