Which of the soil textures listed below has the highest porosity and lowest bulk density?

Clay has the highest porosity and lowest bulk density among the soil textures listed. This is attributed to its small particle size and the ability to retain a significant amount of water within its pore spaces. Clay particles are tightly packed, creating numerous microscopic voids that enhance the soil's capacity to hold water and nutrients.

Because of the high surface area and the aggregates formed by clay particles, it also creates a structure that allows for increased porosity. In comparison, sandy loam and loam have larger particles and, while still having good porosity, do not reach the levels found in clay. Silt, while finer than sand and larger than clay, also does not match clay in terms of porosity due to its intermediate particle size. Thus, clay stands out as the texture with the highest porosity and the lowest bulk density.