Cover crops help conserve nitrogen in the soil.

• A. Potash
• B. CO2
• C. Heat
• D. Nitrogen

Answer: (D)

Conserving nitrogen means keeping the soil’s nitrogen available for plants and reducing losses. Cover crops achieve this by capturing excess nitrogen that would otherwise be lost, especially during off-season periods. As they grow, they take up nitrate and other forms of nitrogen, which helps prevent leaching into groundwater. When the cover crop dies or is incorporated into the soil, that nitrogen returns to the soil in organic form and is slowly mineralized, making it available for subsequent crops. Some cover crops, particularly legumes, can fix atmospheric nitrogen, adding new nitrogen to the soil instead of just recycling it. Building soil organic matter from the cover crop also helps retain nitrogen by improving soil structure and its capacity to hold nutrients. So nitrogen is the nutrient being conserved. Potassium, carbon dioxide, and heat relate to other soil or plant processes but do not describe nitrogen conservation in this context.