Slow-Release Nitrogen Fertilizers and Nitrogen Additives for Field ...

Slow-Release Nitrogen Fertilizers
and Nitrogen Additives
for Field Crops
Dave Franzen
North Dakota State University

Nitrogen Management-
The problem that has built
many careers

Ammonia volatilization from urea
Nitrification
Denitrification

Nitrogen use efficiency-
Worldwide about 33% NUE
(Raun and Johnson, 1999)

Spring Wheat N timeline
Application
Period of greatest uptake
Day 1 Day 30 Day 60 Day 90

Corn N timeline
Application
Period of greatest uptake
Day 1 Day 45 Day 80 Day 120

-Nitrification inhibitors
-Urease inhibitor additives
-Nitrification and urease inhibitor
-Urease inhibition through chemical binding
with urea as applied with slow-release properties
-Urease inhibition through physical separation
of urea from soil

Nitrification inhibitors-
N-Serve®
nitrapyrin (2-chloro-6-[trichloromethyl] pyridine)
DCD, dicyandiamide

Spring N,Touchton
et al., 1978
Fall N, Touchton et al., 1978

Some studies showed a yield increase with
N-Serve, while others showed no yield
increase. Yield increases were more a
result of weather between application and N
uptake rather than performance of the product.
Yield increases over the seven years in Minnesota
were 15 bushels per acre more for fall
anhydrous ammonia + N-Serve over fall
anhydrous ammonia alone, and 27 bushels per
acre more for spring anhydrous ammonia
compared to fall anhydrous ammonia
(Randall et al., 2008).

Instinct ® is a new formulation of
Nitrapyrin that can be mixed with
ammonium fertilizers and can stay on the
soil surface without incorporation.
Research so far at Minnesota, Illinois,
Iowa and Nebraska have shown no yield
benefit to the use of Instinct over N
fertilizer alone, although the product
inhibits nitrification
(Kentucky, Schwab, unpublished data)

Wisconsin-
Corn yield increase with Instinct in
2008, but not 2009.

DCD
No. of comparisons
With
Total significant
advantage
Average
response
%
Timing
Fall 4 1 +1.6
Spring 15 3 +3.4
Sidedress 3 1 +1.4
N Source
Ammonium sulfate 2 0 -1.0
Anhydrous
ammonia
6 1 +3.6
Urea 4 4 +2.2
From Malzer et al., 1989

Yield increases with DCD
were more consistently achieved
in potato in the Malzer survey.

NBPT (N-(n-butyl) thiophosphoric acid triamide)
Agrotain
Competes for active sites on the urease
enzyme and ties up activity for about 10 days,
depending on weather conditions.

Effect of seed-placed urea with and without Agrotain,
on stand density and grain yield of barley on a fine sandy loam
soil, 1994-96. (From Grant, 2004).
N rate, lb/acre Stand, plants/foot Yield, bu/acre
No
Agrotain
Agrotain
No
Agrotain
Agrotain
0 7.6 7.6 50 50
18 7.9 8.2 55 52
36 7.3 7.7 53 62
54 6.0 7.1 59 57
72 5.7 7.1 63 61
89 4.7 7.1 57 65

Yield for side-dressed no-till corn in Hardin County, KY.
(From Schwab and Murdock, 2009)
Treatment
Yield, bushels per acre
Check (50 lb N/acre preplant
N only) 117d*
Urea
158c
Urea + Agrotain
201b
SuperU
201b
UAN
150c
UAN + Agrotain
179bc
UAN + Agrotain Plus
175bc
Ammonium nitrate
239a

Indiana- Purdue, unpublished work by
Phillips, Mengel and Walker, 1989.
Corn Yield
bu/acre
Urea surface applied 130
Urea surface applied +Agrotain 143

Illinois, average of four southern Illinois
locations, Varsa et al., 1999.
Corn Yield
bu/acre
Urea surface applied 106
Urea surface applied +Agrotain 125

Nitrification and urease inhibitors
Ammonium thiosulfate
Nutrisphere ®

ATS has nitrification and urease inhibiting
properties.
It is not as effective generally as nitrapyrin, DCD,
or NBPT.
ATS is most effective as a nitrification inhibitor
at concentrations of 25 ppm S (About 0.1% ATS).
Under warm conditions (>60 o F), mineralization
is complete in a week.
Under cooler temperatures, mineralization is
slower; about 3 weeks.

In a fall application of aqua ammonia with ATS
compared with nitrapyrin, similar ammonia
concentration was found in the spring
with the two products (Goos and Johnson, 1999.)

ATS affects the both steps of
nitrification- ammonium to nitrate
and nitrite to nitrate.
Higher than recommended concentrations
of ATS can result in an accumulation of
nitrite. Studies that used the
recommended concentration of ATS
did not see an accumulation of nitrite.

Nutrisphere,
SFP Specialty Products, LLC, Leawood, KS
Formulation for dry fertilizer-
30-60% maleic-itoconic copolymer,
pH 2.5-5
Formulation for liquid fertilizer-
40% maleic-itoconic copolymer, pH 1-2

Product literature states that nitrification
inhibition is based on product ability
to tie-up copper- a critical metal used
by nitrification bacteria.
Inhibition of urease activity is due
theoretically to a tie-up of soil nickela
critical metal constituent of urease
enzyme.

Effects of N additive, averaged over source (UAN and urea) and N
rate on corn grain yield, earleaf-N and grain-N, Scandia, KS
(2-year average). From Gordon, 2008.
Treatment Yield, bu/acre Earleaf N, % Grain N, %
Check 152 1.72 1.13
Urea/UAN 168 2.57 1.26
ESN 185 2.96 1.33
Nutrisphere-N 183 2.96 1.35
Agrotain 183 2.98 1.36
LSD 5% 6 0.09 0.04

(Research by R.J. Goos, in Franzen et al., J. Plant Nut 2010?)

(Research by R.J. Goos, in Franzen et al., J. Plant Nut 2010?)

Cumulative ammonia volatilization losses for urea, ammonium
sulfate, urea + NBPT, and urea + 0.25% Nutrisphere (NSN)
from a Dewitt silt loam soil during a 15-day laboratory incubation
at 25°C. (Norman data, University Arkansas, Fayetteville,
from Franzen et al., 2010?)
N sources
Days after N source application
3 7 11 15
Cumulative NH 3 loss, % of N applied
Urea 14.5 35.9 51.8 56.9
Ammonium sulfate 0.1 0.2 0.5 0.6
Urea + NBPT † 0.006 2.7 12.9 18.3
Urea + 0.25% NSN 17.6 42.2 57.8 62.7
LSD(0.05) ‡
LSD(0.05) § 12.2
9.6

Laboratory studies clearly show that
Nutrisphere has no nitrification or urease
inhibiting properties. What is most curious
is why some studies show some response.
No Response Positive
North Dakota 8 0
Kansas 7 5 (4 at Scandia)
Minnesota 2 0
Illinois 3 1
Arkansas/Mississippi 3 0
Montana work on barley showed a yield increase,
but no increase in N uptake.

One possible reason for the yield increase
is the pH of the product, particularly with
the liquid formulation. Acid pH lowers the
rate of nitrification. Perhaps it is not
the Nutrisphere that is active. Perhaps it is
its acidity?

Urease inhibitors through chemical binding with
urea and slow-release properties
Nitramin- Triazole-methyl urea
CoRon (19.6% methyl-urea, methyl-diurea,
urea (8.6%)
N-Pact (9.6%) Methyl-triazole, urea (17.4%)

Effect of Georgia-Pacific 43-0-0 Nitramin amended urea compared to
urea surface applied in no-till spring wheat, 2008 near Valley City,
ND. Franzen, unpublished data.
Treatment
Lb Yield, Protein, %
N/acre bu/acre
Check 0 38 12.1
Urea 30 46 12.4
60 51 13.3
90 57 14.1
120 63 15.1
Urea +Nitramin 43-0-0 30 45 12.7
60 57 13.3
90 60 14.4
120 58 15.0
LSD 5% 6 0.7

South Dakota work on Nitramin blends
found no increase in corn yields in 2007,
or spring wheat yield in 2008, but grain
protein was increased in 2008, suggesting
some slow-release properties by the
fertilizer.
(Bly and Gelderman, 2008;2009)

Application of 2 gallon per acre 30-0-0 Nitramin at several barley
growth stages near Valley City, ND, 2008. Franzen, 2009.
Treatment
Yield,
bu/acre
Protein,
%
Check 117 13.4
2-leaf 125 12.8
Early jointing 116 13.3
Boot 109 13.3
Anthesis 119 13.2
LSD % 6 NS

Similar applications of Nitramin to
spring wheat had no positive effect
on wheat yield or protein..
Applications of N-Pact at the 4-5 leaf
stage or post-anthesis had no effect
on grain yield or protein at rates of
2-3 gal/acre

Valley City, 2008, 0-2-3 gal/a N-Pact 5-6 leaf
yield with preplant N rate- urea

Valley City, N-Pact 5-6 leaf, flag-leaf N after
preplant urea, 2008.

Valley City protein response to 5-leaf N-Pact
application over preplant urea rates, 2008.

Yield response from post-anthesis application
N-Pact, 3 gal/acre over preplant urea. Valley
City, 2008.

Protein response of post-anthesis N-Pact
application, 3 gal/acre. Valley City, 2008
Only point of increase

Effect of foliar treatment of spring wheat near
Valley City, on yield, test weight and protein, 2008
Treatment Yield Test weight Protein
Check 68.3 58.2 12.5
3.5 leaf 1 gal/a 65.7 58.0 11.9
3.5 leaf 3 gal/a 66.3 57.9 12.5
Early joint 1 gal/a 60.2 57.7 13.0
Early joint 3 gal/a 57.5 57.0 11.2
Early boot 1 gal/a 67.3 58.2 13.4
Early boot 3 gal/a 62.2 57.3 11.8
Flowering 1 gal/a 59.0 57.4 11.9
Flowering 3 gal/a 65.5 57.5 12.5
LSD 5% NS NS NS

2009 Carrington, ave. 2 sites, post-anthesis
application for protein enhancement. Schatz
15
14.5
14
13.5
Irr Faller
Lebsock
average
13
untreated
check
10 gal UAN 12 gal Coron 2 gal Coron
Faller yields over 100 bu/acre
Slide courtesy of Greg
Endres, NDSU, Carrington REC

Urease inhibition through physical
separation of urea from soil
These are fertilizers with physical
coatings. The most common fertilizer
of this type being marketed across the
region is ESN by Agrium

Illinois-
4 locations over 12 years, ESN was similar
in corn yield to urea + Agrotain, and 3 bu/a
higher in yield than urea alone.
In 4 years of no-till, ESN was 21 bu/a better
than urea surface-applied.
(Ebelhar et al., 2010)

Minnesota-
3 different ESN application methodsdeep
band (4 inches), broadcast incorporated
fall and spring resulted in similar corn yield
to urea using the same methods over a
4-year period.
(Randall and Vetsch, 2009)

Kansas-
At drier locations, ESN not beneficial
to corn or grain sorghum.
At wetter locations, some studies showed
a benefit to its use.
(Weber et al., 2009a and 2009b)

In Michigan in winter wheat,
fall ESN at the 60 lb N/acre rate
produced higher yield than urea.
Not at the 90 lb N/acre rate.

50/50 blends of urea/ENS?
KS studies (Weber and Mengel, 2009)
compared to straight ESN or Urea.
Results showed that in some years, the
blend was superior, and in some years it
was not.

SUMMARY-
Nitrapyrin and DCD are proven nitrification
inhibitors. Their use is limited due to the
inability to predict when they would be
economically beneficial. Growers tend
to use these products to push
their timing and spread work loads, rather
than use them to improve overall N use
efficiency

SUMMARY-
Agrotain is a proven urease inhibitor.
Its use is becoming increasingly more
common in no-till systems that still
rely on surface application of urea.

SUMMARY-
Ammonium thiosulfate is a limited use
nitrification and urease inhibitor due to
the rate of mineralization of the fertilizer.
It may be of some value if used at the correct
rate, but other products appear to be
more consistent in their activity.

SUMMARY-
Nutrisphere has no nitrification or urease
inhibition properties and should
not be used for these purposes.
Within the small number of yield increases,
most are not related to N uptake by the crop.
These yield increases are curious and should be
investigated by the company to determine
the reason for yield increases.

SUMMARY-
Slow-release fertilizers produced by
chemical bonding with urea have
slow-release properties and have been used
in the turf industries for years. Their release
into field crops has met with mixed
success. Rates comparable to those of
traditional fertilizer products may be useful
as slow release products, but their cost
would be prohibitive. Use as a low-rate
substitute for recommended N rates has
not successfully improved crop yield or quality.

SUMMARY-
Positive results have been shown with ESN
in several states when weather conditions
might result in loss of conventional urea
products. Its cost makes it much more
competitive as a slow-release product compared
to the triazole-, methyl-urea based products.