Which characteristic of soil affects its ability to retain nutrients?

The ability of soil to retain nutrients is primarily influenced by its pore space. Pore space refers to the voids or gaps between soil particles that can contain air or water. This characteristic is crucial because it determines how much water and nutrients the soil can hold.

Soils with a greater amount of pore space can store more water, which helps in dissolving and holding onto nutrients. When soil has the right balance of pore sizes, it can retain moisture while also allowing for adequate drainage, ensuring that nutrients remain accessible to plant roots without being washed away.

In contrast, while soil color can indicate organic matter content or level of moisture, it does not directly influence nutrient retention. Soil pH does impact nutrient availability, as certain nutrients become more or less available at different pH levels, but it does not directly govern the soil's capacity to hold those nutrients. Soil temperature can affect microbial activity and organic matter breakdown, indirectly influencing nutrient availability, but it is not a primary factor in the soil's ability to retain nutrients. Thus, pore space is the key characteristic that directly relates to nutrient retention in soil.