Nitrogen Use Efficiency as Influenced by Crop Response Index. G.V. Johnson, W.R. Raun, R.W. Mullen, R.L. Westerman and B.B. Tucker Department of Plant and Soil Sciences Oklahoma State University R.A. Olson Department of Agronomy University of Nebraska
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Nitrogen Use Efficiency as Influenced by Crop Response Index. G.V. Johnson, W.R. Raun, R.W. Mullen, R.L. Westerman and B.B. Tucker Department of Plant.
Improving Nitrogen Use Efficiency for Cereal Production Raun and Johnson Agron. J. 91: Worldwide NUE = 33 % 1 % change = $234,658, 462 Raun and Johnson Agron. J. 91: Worldwide NUE = 33 % 1 % change = $234,658, 462
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Nitrogen Use Efficiency as Influenced by Crop Response
Index.
G.V. Johnson, W.R. Raun, R.W. Mullen, R.L. Westerman and B.B. TuckerDepartment of Plant and Soil SciencesOklahoma State University
R.A. OlsonDepartment of AgronomyUniversity of Nebraska
RI > 1.5
RI < 1.5
Higher NUE
LowerNUE
Apply more N
Apply less N
Potential for increased yield
Response Index
Improving Nitrogen Use Efficiency for Cereal Production
Raun and Johnson. 1999. Agron. J. 91:357-363.Worldwide NUE = 33 %1 % change = $234,658, 462
Improving Nitrogen Use Efficiency for Cereal Production
Potential Improvements Crop RotationsForage Production SystemsHybrid or CultivarConservation TillageNH4-N SourceIn-Season and Foliar-Applied NFertigationHigh Resolution Precision Management
Improving Nitrogen Use Efficiency for Cereal Production
Cause of low NUECause of low NUESoil-Plant system leaksSoil-Plant system leaks
Loss increases with excess mineral-NLoss increases with excess mineral-N
Leaching
Denitrification
NO, N2O
Fertilizers
Plant Uptake
Nitrification NO3
-
NHNH44++
N2
+ H2ONH3 + OH+ OH--
Harvest
+ OH+ OH--
NH3
Volatilization
Loss of N from soil-plant systemLoss of N from soil-plant system
Harvested-N1 - Harvested-N0 Fertilizer-N1
X 100 = NUE
Effect of N on Wheat Yield and NUE (1979-1998)502-Lahoma, OK
0500
10001500200025003000
0 20 40 60 80 100 120N rate (kg/ha)
Yiel
d (M
g/ha
)
102030405060708090
NUE(
%)Yld
NUE
Influence of year on NUE winter wheat receiving 90 kg N/ha.
What is the temporal variability of fertilizer-N response?
Response Index (RI) Response Index (RI) RI = Max yield NRI = Max yield Nxx / yield N / yield N00
RI = Indication of the degree to which RI = Indication of the degree to which N, external to the growing N, external to the growing environment, is needed to support environment, is needed to support potential yield.potential yield.
Temporal variability of wheat response to N
y = 0.04x + 1.37C.V. = 35
0.0
1.0
2.0
3.0
4.0
5.0
1 3 5 7 9 11 13 15 17 19 21 23 25 27
Years
Resp
onse
Inde
x
Relationship of fertilized and non fertilized yield to R.I.
R2 = 0.62 R2 = 0.17
0.0
1.0
2.0
3.0
4.0
5.0
0 1000 2000 3000 4000 5000Wheat yield (kg/ha)
Resp
onse
Inde
x
ControlMax Yld-N
Irrigated maize and sorghumIrrigated maize and sorghum
Effect of UAN-N on irrigated maize and sorghum yield and NUE (Mead, NE, 1969-83)
1.02.03.04.05.06.07.08.09.0
10.0
0 90 180 270N rate (kg/ha)
Yiel
d (M
g/ha
)
10
20
30
40
50
60
NU
E (%
)
Corn YldSorghum YldCorn NUESorghum NUE
Response Index for irrigated maize and sorghum over time.
0.51.01.52.02.53.03.54.0
69 71 73 75 77 79 81 83
Years
Res
pons
e In
dex Maize Sorghum
Conclusions
NUE of wheat is usually < 70 % at low NUE of wheat is usually < 70 % at low fertilizer-N rates and decreases with fertilizer-N rates and decreases with increasing N input.increasing N input.
NUE for maize and sorghum is usually NUE for maize and sorghum is usually < 50 %.< 50 %.
Supply of non-fertilizer N to crop Supply of non-fertilizer N to crop changes greatly from year to year.changes greatly from year to year.Soil moisture and temperature variability?Soil moisture and temperature variability?
Conclusions:
Response to fertilizer-N is influenced Response to fertilizer-N is influenced more by external N inputs and more by external N inputs and mineralized soil-N (Nmineralized soil-N (N00 yield) than by yield) than by potential yield, in a given year.potential yield, in a given year.
Since this is found for soil that has not Since this is found for soil that has not received fertilizer N for over 20 year, it is received fertilizer N for over 20 year, it is even more likely to occur in fields that have even more likely to occur in fields that have a history of receiving fertilizer-N each year.a history of receiving fertilizer-N each year.
Conclusions
NUE may be improved by knowing NUE may be improved by knowing the response index and avoiding the response index and avoiding excess fertilizer-N.excess fertilizer-N.
Identify potential yield each year.Identify potential yield each year. Identify non-fertilizer N contributions.Identify non-fertilizer N contributions. Apply fertilizer-N in-season.Apply fertilizer-N in-season.