Soil Analysis and Improvement
Soil provides water and nutrient reservoir for plants.
To grow a successful landscape it is important to know both the original
status of the soil – its
structure and nutrient content in order to determine what plants will do
well. Soil classification takes into account particle size, from silts and
clays with the smallest particles to sands and gravels with the largest particles.
The smaller the soil particles, the greater the surface area, and the slower
that water moves through the soil. There are also geochemical properties
of different soils which can promote the growth of adapted plants. Customers
should be encouraged to get there soil tested as a first step in preparing
a water wise landscape.
Soil depth provides a greater space for storing water, and adding organic
materials provides the proper environment for healthy roots for many plants
(care should be taken to ensure that plant which have evolved in low-nutrient
soils are not planted where excessive fertility may actually harm the plant).
The first step in preparing a water wise landscape is getting soil tested
to determine its depth, classification and nutrient levels. With that information
soil amendments can be added to increase soil depth, and add organic material.
Compost is used to supply nutrients to plants and improve
the water holding capacity of the soil through the introduction of organic
material. Introduction of compost as a top dressing can assist in replacing
nutrients in soils which have been depleted. Top dressing has the advantage
of not destroying or damaging the roots of existing landscape plants.
Programmatic approaches include education and distribution of free or discount
compost. Education can be offered in form of brochures, or workshops in conjunction
with home and garden shows, or other garden or lawn care related events.
Local cooperative extension officers may offer these services and may be
willing to collaborate with a water conservation program to deliver an educational
program involving soil improvement including compost.
Incentive approaches include offering free or discounted compost.
Waste water treatment plants produce bio-solids which if properly managed,
can be used to produce compost. Some utilities have marketed bio-solids based
compost to farmers, gardeners, as commercial nursery and landscape businesses,
as an additional revenue stream for the utility. Free or discounted samples
can be used to both increase water conservation through soil improvement
and to promote the utilities compost product. Some caution in using bio-solids
is important to ensure that temperature in the composting operation are high
enough to destroy fecal bacteria, and that the waste stream does not include
large quantities of heavy metals, pesticides or other toxic chemical effluents.
Properly composted materials generate sufficient heat (130 to 170 degrees
Fahrenheit) to virtually eliminate human and plant pathogens. For example,
the City of Austin produces “Dillo DirtTM,”3 through
mulching of brush and plant material; combining with bio-solids from the
water treatment plant(s); active composting for over a month; followed by
curing for several months, and screening prior to sale.
Another important aspect of proper soil analysis and improvement
is preparation for and increase in the landscape’s drought tolerance.
Especially important is adequate levels of potassium in the lawn, especially
for turfgrass plants. And during times of low water availability, customers
should be reminded not to fertilize with high nitrogen fertilizers, as they
stimulate leaf growth and water demands for the plants.4
"Compost is used to supply nutrients to plants and improve the water holding capacity of the soil..."|
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Photo courtesy Carol Cammack, TCE