July 2022 - 46

GARDEN PHARMACY
The Dirt on Soil Amendments
Your customers are going to be looking for
recommendations - here are the basics
on soil amendments and fertilizer.
N
ow that summer is here and the gardening season
is in full swing, your customers will start asking
about fertilizers and soil amendments to grow their
best gardens. In order to suggest to them the right soil
amendment, they should first have their soil tested -
either from take home soil test kits you offer, or by sending
samples to your local Extension office.
Here are some basic terms your staff should know when
discussing soil amendments and fertilizer.
Soil Amendments
Soil amendments modify the soil structure as they
decompose, allowing it to absorb and retain water and
nutrients more efficiently. Soil-borne insects, worms, fungi
and other organisms help decompose organic material,
but require energy from available nitrogen in the soil to do
so. For this reason, the soil must often be augmented with
nitrogen when undecomposed (not composted) organic
amendments are applied. Many products classified as
natural organic fertilizers are also organic soil amendments.
Organic soil amendments include hay, straw, peat
moss, leaf mold and sawdust. Gypsum is an example of
a nonorganic amendment added to soil to improve water
infiltration on high-sodium soils.
Fertilizer
Synthetic fertilizers are chemically manufactured materials
containing one or more of the primary nutrients necessary
for plant growth: nitrogen, phosphorus and potassium.
Natural organic fertilizers are derived from either plant or
animal products containing a significant quantity of one or
more of the primary nutrients necessary for plant growth:
nitrogen, phosphorus and potassium. Nutrient content
must be labeled on the package. Most natural organic
fertilizers also provide significant quantities of organic
matter, so they can also be classified as soil amendments.
46 | LAWN & GARDEN RETAILER | JULY 2022
Natural organic fertilizers include manures, sewage
sludge and bone meal.
Quick-Release Fertilizers
Quick-release fertilizers, also known as " fast-acting "
fertilizers, are water-soluble chemicals that once applied
are readily available to the plant. If properly applied, plants
green up quickly.
However, if too much is applied, quick-release fertilizers
have a tendency to burn turf. These materials are easily
leached with rain or over-irrigation and require frequent
application. They are the least expensive fertilizers and are
always synthetic products.
Quick-release fertilizers include ammonium nitrate,
ammonium sulfate, calcium nitrate and urea.
Slow-Release Fertilizers
Slow-release fertilizers, sometimes called water-insoluble
types, release nitrogen over time. They are often applied
at higher rates and less frequently than quick-release
formulas. The initial response of turf is slower than quickrelease
types but these materials continue to provide
nutrients over a period of eight to 10 weeks or more. They
will not burn the turf even if applied at high rates and are
not prone to leaching. These products are a little more
expensive and include certain synthetic fertilizer products
and all-natural organic fertilizers.
Slow-release fertilizers include sulfur-coated urea, urea
formaldehyde, isobutylidene diurea (IBDU) and organic
fertilizers.
Slow Release-Quick Release Mixtures
Some fertilizers are formulated with both water-insoluble
(slow-release) and water-soluble (quick-release) nitrogen.
Plants green up quickly and continue to receive nutrients
over a period of time. For the most effective product, at
least one-fourth of the nitrogen should be in the waterinsoluble,
or slow-release, form.
Source: Agriculture and Natural Resources, University of
California
July 2022

Table of Contents for the Digital Edition of July 2022
