In terms of chemical makeup, humus possesses the highest proportion of:
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Answer: C. Carbon
Explanation
Humus consists of decomposed organic matter containing an exceptionally high proportion of carbon. Organic molecules in decayed plant and animal residues are primarily built from carbon atoms. Chemical analysis reveals carbon dominates the elemental makeup of mature soil humus layers. Soil organic matter forms through the microbial decomposition of dead plant and animal tissues. Carbon sequestration in humus plays a vital role in regulating global carbon cycles. Humus improves soil structure and enhances water retention capacity for agricultural crops.
Farmers measure soil carbon levels to determine fertility and overall agricultural productivity potential. Forest ecosystems accumulate deep humus layers that nourish understory plants and trees effectively. Enhancing soil organic carbon helps mitigate greenhouse gas accumulation in the atmosphere. Option A is incorrect because nitrogen represents a smaller percentage of humus content. Option B highlights oxygen which is present but not the dominant elemental component. Option D is wrong as hydrogen forms bonds with carbon but exists in lesser proportions.
- Subject
- Agriculture
- Category
- Forestry
- Topic
- —
- Difficulty
- medium
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