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 - 1873
Bray’s Nutrient Mobility Concept
Root SystemSorption Zone Root Surface
Sorption 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 GoalsYield 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
9019
7119
7219
7419
7519
7619
7719
7819
7919
8019
8119
8219
8319
8419
8519
8619
8719
8819
8919
9019
9119
9219
9319
9419
9519
9619
9719
9819
9920
0020
0120
0220
0320
0420
0520
06
Gra
in y
ield
, bu/
ac
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
Opt
imum
N R
ate,
lb/a
c
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 Beets
Malting 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 [email protected] available @ www.npk.okstate.eduTwitter: @OSU_NPKYouTube Channel: OSUNPK
www.extensionnews.okstate.edu