Big dogs and beautiful lawns are not compatible. If you want
a beautiful backyard, don't think that you can turn a dog or
even rambunctious children loose to romp and stomp.
The pitter-patter of little feet signal devastation to lawn
grasses. Not only do grasses suffer, but all plants, even the
majestic redwoods of California, cannot endure the consequences
of foot steps. Giant Sequoia trees, over 2,000 years old, began
to decline for no known reason. Finally it was discovered that
hundreds of people walking around and around at the base of
the trees and looking up—fascinated by the size and height
of the trees—were trampling to death these natural monuments.
The problem? Soil compaction.
Compaction destroys soil structure, thus increasing density,
carbon dioxide concentrations (plant roots need oxygen to live
and grow) and heat build-up. Additionally, it creates surface
runoff rather than allowing water to penetrate the roots. Compaction
subsequently decreases the amount of large pore space available,
as well as oxygen in the soil, water penetration, and nutrient
When compaction increases soil density, root elongation is
inhibited, causing poor development of root systems essential
for summer survival. This damage is more severe in drier, heavier
Plant roots need oxygen to survive, and as the density of
a compacted soil increases, carbon dioxide and other toxic gasses
do not readily move from the root system. Their concentration
can build up to the point that they actually become toxic to
Compaction is very much a surface phenomenon affecting mainly
the top 4 inches of soil. Compacted soils do not allow rapid
water penetration, causing increased runoff. This means that
more irrigation is necessary to adequately soak compacted areas
to get water to the root-feeding zone during times of drought
Compacted soils are hotter in the summer and colder in the winter
because of the conductivity of tight soil particles. Lower temperatures
in the spring could result in less root growth, delayed green-up
and even winter- kill.
Porosity of compacted soil is less. Both the numbers of pores
and their size are decreased. Small pores in soil are usually
filled with water, so water begins to replace air in a compacted
soil. In the absence of air, plant root cannot actively absorb
nutrients, causing plant decline. Pathogenic fungus organisms
thrive in higher soil temperatures in the presence of a lack
of oxygen. Thus, the probability of summer disease problems
is increased in a compacted soil. Weeds that can persist in
low oxygen soils can gain the competitive edge over desirable
grasses and take over.
Managing turf to minimize the negative effects of compaction
is important. Management considerations that are helpful in
this regard include aerification, traffic control, water management,
soil modification, efforts to both improve drainage and irrigation
design, and turf grass selection.
Core aerification is extremely beneficial in increasing air
exchange, water infiltration rates, water retention, nutrient
penetration and thatch decomposition. It also decreases surface
runoff, therefore increasing water- use efficiency while reducing
total irrigation requirements. Warm-season grasses such as St.
Augustine and bermuda can be beneficially aerified from the
time they green-up until the time they go dormant in the fall.
Once-a-month aerification on heavily trafficked Bermuda grass
would not be detrimental. Total number of aerifications per
year needs to be linked to fertility levels and amount of traffic.
Two to five aerifications per year should be considered average
for heavily-trafficked turf.
Minimizing traffic whenever possible is important. Minimizing
traffic when soil is wet is critical because compaction damage
is greater on a wet soil than on a dry soil. Timing irrigation
to allow adequate time for drainage prior to traffic can be
a critical factor in reducing compaction damage.
For more information about dog and animal compaction control,