Transcript Slide 1


Part of
› Amino Acids: Building blocks of proteins
› Enzymes: responsible for all biological
process
› Nucleic Acids
› Cholorphyll
Needed for Carbohydrate use
 Increases root growth


Excess nitrogen flowing down the
Mississippi each year is estimated to be
worth $750,000,000 (Science, Malakoff,
1998)

NUE in cereal production must be
improved
Raun and Johnson, Agron J. 91:357-363

Growth is controlled not by the total of
resources available, but by the scarcest
resource.
› Only by increasing the amount of the limiting
nutrient (the one most scarce in relation to "need")
was the growth of a plant or crop improved.
Justus von Liebig
1803 - 1873
Plants respond to the total
amount of mobile nutrients
present
Plants respond to the
concentration of immobile
nutrients present
Root System
Sorption Zone
Mobile Nutrients
Nutrient limitation directly
related to yield potential,
and dependent on the
environment
Root Surface
Sorption Zone
Immobile Nutrients
Nutrient limitation expressed as
a % of potential yield, or
“sufficiency”, and
independent
of the environment
Yield Goals: average of last 5 years +20%
average of the last 3 best years.
Yield Goal includes, grain and forage/lbs of meat
Nebraska study showed that farmers overestimated
yield by 2 Mg ha-1 (32 bu ac-1), resulting in an excess
of 35 kg N ha-1 (Schepers et al., 1986)
Over-optimistic yield goals were the largest
contributor to excess N applications with average
yield goals exceeding actual yields by over 15%,
only about 30% of the fields were within 5% of the
yield goal
(Daberkow et al., 2001)

Nitrogen Recommendation =
Yield Goal N rate – Residual N

Residual N is
› 0-6” (Top-soil) Soil Test NO3
› 6-18” (Sub-soil) Soil Test NO3
› NO3 from irrigation
› Cover Crop Credits.
80
60
1971
1972
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Grain yield, bu/ac
Long-Term Winter Wheat Grain Yields, Lahoma, OK
90
0-40-60
Exp. 502, 1971-2006
100-40-60
70
Ave Yld 42 bu/ac
50
40
30
20
10
0
“After the FACT” N Rate required for “MAX Yields” Ranged
from 0 to 140 lbs N/ac
140
Exp. 502, 1971-2006
Optimum N Rate
Avg. 49 lb N/ac +/- 39
Max Yield
Avg. 43 bu/ac +/- 13
100
80
60
40
20
0
19
71
19
74
19
76
19
78
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
20
02
20
04
20
06
Optimum N Rate, lb/ac
120
1.
2.
3.
4.
Right Source
Right Place
Right Rate
Right Time
IPNI: International Plant Nutrition Institute
Anhydrous Ammonia NH3
 Urea
 Liquid UAN
 DAP, MAP, APP
 Coated N (sulfur and Polymer)


Corn vs wheat vs forages

Cereal Grains, Cotton, Sugar Beets
Malting Barley
Yield Goal
 Soil Testing
 Sensors


Pre plant and Top-dress/ Side-Dress
› Winter Wheat
› Corn

Forage Systems
› Spring, summer, fall
www.extensionnews.okstate.edu
Brian Arnall
373 Ag Hall
405-744-1722
[email protected]
Presentation available @
www.npk.okstate.edu
Twitter: @OSU_NPK
YouTube Channel: OSUNPK