Which term includes substances such as nitrates or manure used to make soil more fertile?

• A. Irrigation
• B. Manure
• C. Fertilizer
• D. Soil Exhaustion

Answer: (C)

Fertilizers are substances added to soil to supply nutrients that crops need to grow better. Nitrates are a form of nitrogen fertilizer, providing a quick supply of nitrogen essential for plant growth. Manure is an organic fertilizer that not only adds nutrients but also improves soil structure and moisture retention. Because this term covers both inorganic sources like nitrates and organic sources like manure, it is the correct way to describe substances used to make soil more fertile. Irrigation focuses on adding water, not nutrients, so it doesn’t fit. Soil exhaustion describes nutrient loss from the soil, not substances that improve fertility.