Which two elements are primarily added to soil by green manure?

The correct option is Nitrogen and phosphorus.

Explanation:
Green manure consists of quick-growing crops, often leguminous plants (such as sunn hemp, dhaincha, or clover), that are grown specifically to be plowed under and incorporated into the soil while still green.

Key Benefits of Green Manure:
1. Nitrogen Enrichment: Leguminous green manure plants have symbiotic bacteria (Rhizobium) in their root nodules that fix atmospheric nitrogen gas into organic forms, significantly enriching the soil with Nitrogen.
2. Phosphorus Enrichment & Availability: Green manure crop roots absorb phosphorus from deeper soil layers and convert it into available organic forms. When these plants decompose, Phosphorus is released into the topsoil, making it accessible to primary crops.
3. Organic Matter & Soil Structure: It adds substantial organic content, improving soil aeration, water retention, and microbial activity.

Thus, the two primary elements added and enriched in the soil by green manure are Nitrogen and phosphorus.