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Nitrogen ManagementIntro to Soils
Nitrogen in the Plant
Part of› Amino Acids: Building blocks of proteins› Enzymes: responsible for all biological
process› Nucleic Acids› Cholorphyll
Needed for Carbohydrate use Increases root growth
SCIENCE Magazine
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
N that is not used is lost
Liebig's Law of the Minimum
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 Liebig1803 - 1873Justus von Liebig1803 - 1873
Bray’s Nutrient Mobility Concept
Root SystemSorption Zone
Root SurfaceSorption Zone
Nutrient limitation expressed as a % of potential yield, or “sufficiency”, and independentof the environment
Nutrient limitation directlyrelated to yield potential, and dependent on the environment
Mobile Nutrients Immobile Nutrients
Plants respond to the totalamount of mobile nutrientspresent
Plants respond to the concentration of immobilenutrients present
Nitrogen is mobile…..
Nitrogen is mobile…..
Yield Goals
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)
N rate recommendation
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.
Exp. 502, 1971-2006
0
10
20
30
40
50
60
70
80
901
97
11
97
21
97
41
97
51
97
61
97
71
97
81
97
91
98
01
98
11
98
21
98
31
98
41
98
51
98
61
98
71
98
81
98
91
99
01
99
11
99
21
99
31
99
41
99
51
99
61
99
71
99
81
99
92
00
02
00
12
00
22
00
32
00
42
00
52
00
6
Gra
in y
ield
, b
u/a
c
0-40-60
100-40-60
Long-Term Winter Wheat Grain Yields, Lahoma, OK
Ave Yld 42 bu/ac
“After the FACT” N Rate required for “MAX Yields” Ranged from 0 to 140 lbs N/ac
0
20
40
60
80
100
120
140
Op
tim
um
N R
ate
, lb
/ac
Exp. 502, 1971-2006
Optimum N Rate Max YieldAvg. 49 lb N/ac +/- 39 Avg. 43 bu/ac +/- 13
4 R’s
1. Right Source2. Right Place3. Right Rate4. Right Time
IPNI: International Plant Nutrition Institute
Nitrogen sources
Anhydrous Ammonia NH3 Urea Liquid UAN DAP, MAP, APP Coated N (sulfur and Polymer)
Nitrogen Placement
Corn vs wheat vs forages
Application
Application
Right Rate
Cereal Grains, Cotton, Sugar BeetsMalting Barley
Yield Goal Soil Testing Sensors
Right Time
Pre plant and Top-dress/ Side-Dress› Winter Wheat › Corn
Forage Systems› Spring, summer, fall
Thank you!!!
Brian Arnall373 Ag Hall405-744-1722b.arnall@okstate.eduPresentation available @
www.npk.okstate.eduTwitter: @OSU_NPKYouTube Channel: OSUNPK
www.extensionnews.okstate.edu
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