Can Sand Harm Clay Soil Lawns?

Soil Texture

• Soil consists of mineral particles of different sizes. Soil mineral particles are either sand, clay or silt. The vast majority of soil contains some particles of each size. The texture of the soil reflects the relative percentage of particles of one size to the others. Loam is the soil in which the particles exist in relatively equal proportions. Loam is very desirable garden soil because it supports the broadest range of plant life.

Clay

• Clays are the finest of the soil particles, measuring less than 0.002 mm in size. Clay creates problems for gardeners in several ways. Clay particles compact together very tightly. The pore space between clay particles is too small to be of much use for air, water or plant roots. Water is more likely to runoff lawns with compacted clay soil. Runoff deprives the roots of water and carries away vital nutrients. Water that does penetrate clay soil tends to stay in place, displace oxygen and will in some instances, suffocate the roots.

Sand

• Sand particles are the largest of the soil mineral particles. They measure between 0.05 and 2.0 mm, the range represents a progression from fine sand to very coarse sand. The large, irregular shaped particles create large pores when the particles come together. Air and water fill the pore space. Water and nutrients run through sandy soil very quickly, at times too quickly to allow plants to absorb the water or nutrients through their root systems.

Sandy Clay Mix

• Sand and clay particles do not mix well on their own. The clay particles are small and smooth. They will slide past the sand particles and clump together within the sand's pore space. By adding sand, you will end up harming the clay soil by creating a "heavier, denser soil with less pore space than either the sandy or the clay soil alone," as noted by Linda Chalker-Scott, a horticulturist with Washington State University. She suggests sand may be able to improve clay soil, but only if you are able to add at least 50 percent of the total volume; a prohibitive task for most lawns.