Define "pore space" in soil.

Pore space in soil refers specifically to the voids or gaps that exist between the solid particles of soil. These pores are crucial because they serve as the storage sites for air and water, both of which are essential for plant growth and the overall health of the soil ecosystem. The amount and size of pore space can influence water retention, drainage, and aeration, all of which are significant factors affecting root development and soil biota.

In the context of soil composition, the solid particles themselves do not define pore space; rather, they are the material that creates the voids. While areas where plant roots grow are related to soil health, they do not themselves describe pore space. Similarly, the top layer of soil often referred to as the "topsoil" is indeed the most fertile layer, but this too does not encapsulate the concept of pore space. Thus, the definition that highlights the voids between soil particles effectively captures the essence of pore space.