Arenas - Horsekeeping on a Small Acreage - page 391

Topsoil. Topsoil is a general term for native soil with various components, primarily clay,
loam, and sand. Generally, topsoil is not suitable for arena footing, as it usually doesn't
drain well, compacts easily, and is dusty. Clay is hydrophilic, which means it has the ability
to absorb water and become a very plastic substance. Clay particles tend to be flat ovals
that are slippery when wet, so they slide into position with each other and hold their shape
when they dry. For outdoor arenas, it is best for clay content to be less than 10 percent.
Loam is a rich soil composed of sand, silt, and clay. Sand is discussed below.
One of the most common ways of improving native soil is to disc sand and/or sawdust
in with the dirt. This will lighten and loosen the soil and increase its drainage while adding
to its cushion.
Sand. The word sand is a vague term used to represent a wide variety of materials.
Sand particles vary greatly in shape, from ball-bearing round to very angular. Round sand
particles interact like a zillion tiny balls, so do not provide the stability required for a
horse's landing, loading, and push off. Beach and riverbed sand is often too spherical
for arenas. Glacial sand, with its irregular angular surfaces, results in more interlocking
particles and therefore better stability and traction.
Sand isageneraltermthatcanrefertobeachsand,builder'ssand,andeverythingin
between. Choose clean sand of medium-coarse, uniform particle size.
Unlike clay, sand has more strength when it is wet; in fact, it often becomes too hard.
When it is too dry, it loses its binding forces and collapses.