Which of these supplements, when added to soil, would not contribute to pollution?

Options

A. Urea
B. Potash
C. Compost
D. Ammonium potash

Answer

To determine which supplement, when added to soil, would not contribute to pollution, we can analyze the options provided:

1. **Urea**: Urea is a nitrogen-rich compound that is often used as a fertilizer. However, it is an excretory product and can lead to nitrogen pollution in the soil, which can harm crops and the environment. Therefore, urea contributes to soil pollution.

2. **Potash**: Potash is a potassium-rich fertilizer. While it is beneficial for plant growth, excessive use can lead to nutrient imbalances in the soil, potentially making it unfertile over time. Thus, potash can also contribute to soil pollution.

3. **Ammonium Potash**: Similar to potash, ammonium potash is a fertilizer that provides both potassium and nitrogen. However, it can also lead to soil degradation and nutrient depletion if used excessively. Therefore, ammonium potash can contribute to soil pollution as well.

4. **Compost**: Compost is made from decomposed organic matter, such as plant leaves and stems. It enriches the soil with nutrients and improves its structure without causing pollution. Since compost is natural and promotes healthy soil, it does not contribute to pollution.

Based on this analysis, the supplement that would not contribute to pollution is **Compost**.

### Step-by-Step Solution:
1. **Identify the supplements**: Urea, Potash, Ammonium Potash, and Compost.
2. **Analyze Urea**: Recognize that it is an excretory product that can lead to nitrogen pollution.
3. **Analyze Potash**: Understand that while it helps plants, excessive use can lead to soil infertility.
4. **Analyze Ammonium Potash**: Note that it can also cause nutrient depletion and soil degradation.
5. **Analyze Compost**: Acknowledge that it is made from organic matter, enriches the soil, and does not cause pollution.
6. **Conclusion**: Identify that Compost is the only supplement that does not contribute to pollution.