Which element is responsible for causing soil salinity? At what concentration does the soil become saline?

Explanation

**Step-by-Step Solution:**

1. **Understanding Soil Salinity**:
- Soil salinity refers to the amount of salt present in the soil. It is an important factor that affects soil health and plant growth.

2. **Identifying the Element Responsible for Soil Salinity**:
- The primary element responsible for causing soil salinity is sodium. However, other salts such as calcium, magnesium, and potassium can also contribute to salinity levels. The increase in salinity is often linked to human activities, particularly the excessive use of fertilizers.

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