The Soil Says it All Many of us here in southern New Jersey have very sandy well drained soil, but some others have clay soils and a few lucky ones have great sandy loam with the right proportions of sand, clay, silt, and organic material.
Grains of sand are largest and most irregularly shaped, while particles of clay are the smallest.
So it stands to reason the grains of sand allow water and air to circulate, while clay particles are much more dense, sometimes trapping water. When it dries out however the clay gets hard because there is no air or organic materials between the particle. Sand drains well, but it also dries out too quickly. Therefore it is important to add humus to the soil so that water might be retained. This past summer those of us with sand found out that constant watering often wasn't enough and even then all the nutrients were leeched out of the soil.