| Howard Fertilizer
distribution partner, Nu Gro Technologies is a leader in the fertilizer
industry, offering the most advanced slow release and controlled-release
products available. Nu Gro’s solutions include Nitroform®,
Nutralene®, Sulfur Coated Urea (SCU) and IB® Nitrogen. Below
is an agronomical summary that, in part, explains why Nu Gro products
are an intelligent choice for any grounds maintenance manager.
Basic Agronomics
Soil Chemistry and Microbial Activity
Many factors are important in the utilization
of plant nutrients. These factors combine soil physical and chemical
characteristics and microbiological activity. Plant nutrients become
available only when they are dissolved in the soil solution. Fertilizer
salts dissociate into positive and negative ions before they are
absorbed and taken into the roots.
Example: potassium nitrate, KNO3, dissolves in
the soil solutions to form K+ and N03-. These positively and negatively
charged ions are attracted to oppositely charged particles (colloids)
of clay and organic matter and to oppositely charged particles on
the root hairs of growing plants.
Nurturing
the Microbial Life of the Soil
The health of the soil is dependent upon many factors
including fertility, pH and adequate moisture to support microorganisms—mainly
bacteria, fungi and actinomycetes. Vigorous microbial activity is
the strongest indication that any given soil will support a thriving
plant community. If well managed, the subsurface eco-system will
likewise benefit from the plants—as rooting activity increases
pore space, and vegetative residue and secretions from roots contribute
to the unseen life of the soil.
Soil microorganisms number
nearly a trillion in each pound of root-zone soil. Over 98% of them
are labeled “the decomposers.” Their functions include
formation of soil aggregates to improve air and water movement;
decomposition of organic matter— including thatch—to
humus; and solubilizing insoluble mineral nutrients such as phosphates,
sulfates and potassium, calcium and magnesium oxides to plant available
forms. The decomposers are also responsible for converting organic
and slowly soluble fertilizer nitrogen to ammonium (NH4+) ions via
of a two-step reaction of mineralization. The microbes initially
convert the nitrogen to amino acids for their own cell structure—
aminization. They get their energy from the carbon that is released
in the process. Ammonium is then formed in the sequential breakdown
of the amino compounds— ammonification. The rate of ammonification
is proportional to the solubility of the compounds. Though plants
can and do utilize ammonium nitrogen, they are more adapted to take
it up in the nitrate (NO3) form.
The process of converting ammonium to nitrate nitrogen
is known as nitrification. The microorganisms involved, ironically,
are not the decomposers, but a separate group of bacteria collectively
named nitrobacter. Unlike the decomposers, nitrobacters derive their
energy completely and directly from carbon dioxide (CO2). The process
of nitrification is rapid in warm soils, and is proportional to
the rate of ammonification. The slower the rate of ammonification,
such as with organic or slow-release fertilizers, the more measured
the conversion to nitrate.
An entirely different form
of nitrogen release is hydrolysis.
Hydrolysis is a chemical reaction that converts one compound into
one or more different compounds in the presence of moisture, usually
with a reactive ingredient. Urease is known as the universal enzyme
because it is secreted by nearly all life forms, plant and animal.
Urease splits urea into ammonia (NH3), ammonium and carbon dioxide.
Like nitrification, urease hydrolysis is very fast in warm soils,
usually complete within seven days during the growing season.
The relationship between mineralization, nitrification
and hydrolysis is important to understand and appreciate nitrogen
release from Nitroform®
and Nutralene® versus
urea. These reacted slow-release fertilizers supply both carbon
(for energy) and nitrogen (for food) to the decomposing microorganisms
that steadily and gradually return ammonium nitrogen back to the
soil. The plants are the second guests at the table. The rate of
mineralization—nitrogen release—closely corresponds
to plant requirements. When soil temperatures are too cold or too
hot for plant growth, the same will be the effect on microbial activity.
But nitrogen from leaching-resistant Nitroform
and Nutralene still remains
in the soil for use by the plants as needed.
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Microbial Action Reduces Thatch Buildup
Fertilizers that enhance microbial activity are
less likely to contribute to thatch formation than those that don’t.
Thatch forms when organic matter accumulates at a higher rate than
decomposition can take place. When microbes are active, thatch levels
decline. Microorganisms need moisture, air and nitrogen to decompose
thatch. The best way to provide these ingredients to soil microbes
is through regular aeration followed by applications of slow-release
nitrogen sources. Directly exposing the microorganism population
to Nitroform or Nutralene
accelerates the microbial degradation process. In addition, it has
been observed that ballmarks and divots heal significantly faster
on golf course turf where Nitroform
or Nutralene has been incorporated
into the soil after aeration.
Root Growth
Turf managers know that growing tall turf is not
necessarily the best management program, certainly for golf courses.
All plant root systems have basically three functions:
Plant anchoring
Nutrient and water uptake
Carbohydrate (nutrient) storage site
Any improvement in the root length or mass potentially
improves these functions, thus producing a healthier plant and one
potentially more drought tolerant. Why? The larger and deeper the
root system, the better opportunity to find water—an important
consideration with recent drought conditions throughout much of
the United States.
Producing rapidly growing turf, whether warm or
cool season turfgrasses, not only causes potential clipping disposal
problems, but actually may weaken the turf root system. Excess nitrogen
availability, such as from soluble sources, can produce excess topical
growth. However, this growth is at the expense of carbohydrate reserves
in the root system, stolons, rhizomes or tillers. This graph demonstrates
that shoot growth is directly at the expense of root (stolons/rhizomes/tiller)
mass.
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Fertilizer Timing & Release Characteristics
It’s a Matter of Time
There are many types of nitrogen sources. Most
fertilization programs use a combination of these sources. Several
may be combined for application at the same time or applied individually
at different times during the year.
Many fertilizer products contain both quick- and
slow-release nitrogen sources.While the quick-release source provides
quick greenup and helps lower the overall fertility cost, the slow-release
component gives a long-lasting effect and adds a margin of safety
from fertilizer burn and nitrate leaching. Turf managers should
also consider the potential annual cost savings with the implementation
of “true” slow-release nitrogen sources into their fertilization
programs. Fewer, longer lasting fertilizer applications may reduce
fertilizing expenses on an annual basis.
Turf managers are well advised to manipulate their
fertilizer programs to provide as uniform growth as possible. That
is why Howard Fertilizer and Chemical has developed several nitrogen
sources to give you superior nitrogen in any fertilizer situation.
You might select Nitroform
as a portion of your nitrogen source for late summer fertilization
because some nitrogen will be released by microorganisms during
hot weather, some during those warm days that occur from time to
time in the fall, and some will be carried over to the following
spring. Nutralene, on the
other hand, would be the right choice for early spring fertilization
when you want fast greenup and sustained feeding for three to four
months with little nitrogen carryover.
IB nitrogen is
an excellent choice for late season/early spring feeding, as its
release is not dependent on temperature.
The environmental aspects of nitrogen applications
deeply concern most turf and ornamental managers today. Because
turfgrasses usually are grown in populated areas, managers must
know the extent to which nitrogen applied to turf may contribute
to water quality. Excessive nitrates in groundwater can be harmful
to humans and livestock if consumed in drinking water. Study after
study shows that slow-release fertilizers reduce subsoil nitrate
concentrations compared to water-soluble fertilizers.
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