Deep versus Shallow Soils: A Look into Soil Amendments and Benefits

The appearance of plants above ground is dependent on the health of the underlying soil biology and moisture availability.   The soil is a living, active thing with beneficial bacteria, microbes, fungi and subsurface insects, decaying plant material and worms.  The principle of healthy soil hinges on its ability to act like a sponge, holding onto water for long periods of time to keep root systems moist, and still have enough air space to let plants breathe. 

Many landscape projects use just the minimum allowed by municipal codes for shallow soil in turf and landscape beds, resulting in placement of topsoil on compacted subgrades that have little or no water percolation beyond the subgrades topsoil is placed upon.  This leads to water-logged lawn areas and tree roots running close to the surface to escape drowning, as illustrated by drawing A below.   Nearby pavements and curbs can become cracked, split or buckled as roots push through looking for air and room to grow.

In section B, deeper soils with composted soil amendments mixed into the subgrade with topsoil, tree and shrub root systems have room to grow, get adequate water, and excess water either percolates deeper into the sub soils and becomes more evenly distributed.  With root guards and compost amended soils, a more healthy landscape and soil profile helps keep the installed plants turgid and healthy.  

The reason soils amended with compost that Tutko Landscaping makes at our Redmond facility helps plants maintain their health is due to the finely chopped and composted fibrous plant materials we process through a large grinder and let compost over several months.  Dead plant material and wood chips act as sponges holding water in their voids, and plant roots seek out such soil and particles.  
Studies on compost amended soils show that peak summer time irrigation demand can be cut by 60% or more in the first year, and returns on investment for converting lawn areas to planting beds with deeper soils can pay themselves.