FUNDAMENTALS OF THE OSU ALGORITHM
FUNDAMENTALS OF THE OSU ALGORITHM
TRAINING
Farmer training, Ciudad Obregon, Mexico, January 2007
VARIABLE N RESPONSE
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
2007
2008
2009
0
10
20
30
40
50
60
70
80
90 Exp. 502, 1971-2009
0-40-60 100-40-60
Gra
in y
ield
, bu/
ac
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
2007
2008
2009
0
1
2
3
4
Resp
onse
Inde
x
GLOBAL IMPORTANCE OF FERTILIZER N
Malakoff (Science, 1998)
$750,000,000, excess N flowing down the Mississippi River
Africa expenditure on fertilizer N, cereals
$706,000,000
Nitrogen Use Efficiency (NUE) World 33%
20% increase
Worth $10.8 billion US annually
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
50 Locations, 1998-2009
PKNP 1998PKSN 1998TPSN 1998PKNP 1999222 1999301 1999EFAA 1999801 1999502 1999PKNP 2000222 2000301 2000EFAA 2000801 2000502 2000HNAA 2000PKNP 2001222 2001301 2001EFAA 2001801 2001PKNP 2002222 2002301 2002EFAA 2002801 2002HNAA 2002502 2003222 2003EFAA 2003HNAA 2003PKNP 2004222 2004301 2004502 2004200520062009INSEY
Gra
in y
ield
, Mg/
ha
YP0 = 0.409e258.2 INSEY R2=0.50YP0 + 1Std Dev = 0.590 e258.2 INSEY
SUB-SAHARAN AFRICA
SAA USA
Population, million 700 300
Cereals, million ha 88 56
Production, million tons 97 364
Yield, tons/ha 1.1 6.5
Fertilizer N, million tons 1.3 10.9
Avg. N rate, kg/ha 4 52
% of world N consumed 1.4 13
% of world population 10 4
YPMAX
INSEY (NDVI/days from planting to sensing)
Gra
in y
ield
YP0YPN YPN
RI=2.0RI=1.5 RI-NFOA
YPN=YP0 * RIRI-NFOAYPN=YP0 * RI
YP0 = (NDVI / Days, GDD>0)YP0 = INSEYYPN = (YP0*RI) Nf = (YP0*RI) – YP0))/Ef
YP0 = (NDVI / Days, GDD>0)YP0 = INSEYYPN = (YP0*RI) Nf = (YP0*RI) – YP0))/Ef
A
YPMAX
INSEY (NDVI/days from planting to sensing)
Gra
in y
ield
YP0
Max Yield-NFOAMax Yield-NFOA
Nf = (YPMAX-YP0)/EfNf = (YPMAX-YP0)/Ef
B
YPMAX
INSEY (NDVI/days from planting to sensing)
Gra
in y
ield
YP0YPN
RI=2.0
RICV-NFOARICV-NFOACVCV
Nf = ((YP0*RI)*(65-CV/65-CrCV)) – YP0/Ef65? Limit of CV dataCritical CV or CrCV, changes for different crops
Nf = ((YP0*RI)*(65-CV/65-CrCV)) – YP0/Ef65? Limit of CV dataCritical CV or CrCV, changes for different crops
C
0
100
200
300
400
500
600
0 10 20 30 40 50CV
Pla
nts
m2
-1
WheatWheat
y = 163862x-0.4636R2 = 0.65
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
100000
0 10 20 30 40 50 60
RCV
Pla
nt
pop
ula
tion
(p
lan
ts h
a -1
)
113-day
99-day
104-day
107-day
111-day
CornCorn
Data compiled by Dr. Robert Mullen, The Ohio State University
VARIABLE RATE TECHNOLOGY TREAT TEMPORAL AND SPATIAL VARIABILITY
RETURNS ARE HIGHER BUT REQUIRE LARGER INVESTMENT
YIELD POTENTIAL PREDICTION, CORN, OHIO
Ohio y = 0.9689e2655.7x
R2 = 0.73
0
2
4
6
8
10
12
14
16
18
20
0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014
INSEY, NDVI / cum GDD
Yie
ld, M
g/h
a
YIELD POTENTIAL PREDICTION, WINTER
WHEAT, OKLAHOMA
PREDICTING N RESPONSIVENESS
0
0.5
1
1.5
2
2.5
3
3.5
0 0.2 0.4 0.6 0.8 1
Field Rate NDVI
Po
ten
tial
Yie
ld,
Mg
/ha
YP0
YPN = RINDVI YP0
YPN = YPmax
Soil/Crop Divide
RI/YPmax Divide
Yield with additional N predicted by Response Index
Yield increase with additional N limited to the maximum potential yield
RESPONSE INDEX THEORY FOR FERTILIZER N RESPONSE
ttanConsRI
YPNRIYPN
NDVI
NDVI
maxYPYPN
NDVI
2aNDVI
NDVI Fp1acosh
Fp0aRI