fertilizer price effect on optimum corn n rate recommendations
DESCRIPTION
Fertilizer Price Effect on Optimum Corn N Rate Recommendations. John Sawyer Department of Agronomy Iowa State University. Historic Nitrogen and Corn Grain Prices. Historic Nitrogen:Corn Price Ratios. Exploring a Regional Approach to N Rate Guidelines. - PowerPoint PPT PresentationTRANSCRIPT
ISU Agronomy Extension
Fertilizer Price Effect on Optimum Corn N Rate Recommendations
John Sawyer
Department of Agronomy
Iowa State University
ISU Agronomy Extension
Historic Nitrogen and Corn Grain Prices
Iowa Corn Grain Price (annual)
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
1960 1970 1980 1990 2000
Year
Co
rn P
rice
, $/
bu
Corn Grain Price
U.S. Average Ammonia N Price (April)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
1960 1970 1980 1990 2000
Year
Am
mo
nia
N P
rice
, $/
lb N
Ammonia N Price
ISU Agronomy Extension
Historic Nitrogen:Corn Price RatiosU.S. Average Ammonia N Price - Iowa Corn Grain Price
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
1960 1970 1980 1990 2000
Year
Pri
ce R
atio
, $/l
b N
:$/b
u
N:Corn Price Ratio
ISU Agronomy Extension
Exploring a Regional Approach to N Rate Guidelines
Diverse N rate recommendation systems across states
Lack of optimum N rate relationship with corn yield
Concerns about N rates with corn yields at record levels
Historically high N fertilizer prices
ISU Agronomy Extension
Corn Yields and N Rates
0
50
100
150
200
250
0 100 200 300Optimum Yield, bu/acre
Op
tim
um
N R
ate,
lb
N/a
cre
Six State SC - 389 Trials
0.10 Price Ratio$0.22/lb N:$2.20/bu
0
50
100
150
200
250
0 100 200 300Optimum Yield, bu/acre
Op
tim
um
N R
ate,
lb
N/a
cre
Six State SC - 389 Trials
0.10 Price Ratio$0.22/lb N:$2.20/bu
ISU Agronomy Extension
Methods for Analyzing N Response Data43 Corn Following Soybean Sites in Iowa ($0.22/lb N:$2.20/bu)
43 Sites 35 Responsive Sites
Method N Rate
Net Return N Rate
Net Return
lb N/acre $/acre lb N/acre $/acre
Mean of EONRs 79 49 97 67
EONR - Mean Yield 104 53 108 69
Maximum RTN 105 51 113 68
Discrete MP 108 51 111 68
Site Optimum 79 60 97 73
Measured Yield† 174 40 177 58
Yield History† 140 47 140 65† 1.2 lb N/bu factor, 50 lb soybean rotation “credit”
ISU Agronomy Extension
Maximum Return To N (MRTN) Database Driven Approach
Previously described by Nafziger, Sawyer, and Hoeft (2004) Accumulate corn N response data from
many recent trials Determine economic response and most
profitable N rates directly from trials in N response database
Data → N Rate Guidelines
ISU Agronomy Extension
N Response Trial Database
3 to 4 replications 5 to 7 N rates Non-irrigated High and very high yield potential soils Experiment station or producer field Corn following Soybean (SC)
and Corn following Corn (CC) Grain yield measured for each N rate N Response curve fit to each trial
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698 Trials> 95% since 1990> 60% since 2000
ISU Agronomy Extension
Six-State Database
Corn–Corn Soybean–Corn State Total Responsive Total Responsive IL 93 82 185 172 IA 60 56 136 121 MI 1 1 9 9 MN 73 68 55 50 OH 5 4 8 7 WI 39 33 34 30 All 271* 244 427* 389* 65 Non-responsive sites, 60% had manure history
Total of 698 trials
ISU Agronomy Extension
Calculation of MRTN 1st - Compile database from corn yield N
response trials for desired rotationExample of a Few Site N Response Trials with SC
50
100
150
200
250
0 50 100 150 200
N Rate, lb N/acre
Co
rn Y
ield
, b
u/a
cre
Clay 03
Boone-SN 02
Harrison 03
Johnson 03
ISU Agronomy Extension
Calculation of MRTN
2nd – For each trial in database calculate Return To N (RTN) using the a, b, c and plateau values from each response curve For every 1 lb N/acre from 0 through 240
lb N/acre calculate the yield increase over the yield obtained with zero lb N/acre
RTN = yield increase times price of corn minus the cost of N
ISU Agronomy Extension
Calculation of MRTNClay 2001 Site -- SC
40
60
80
100
120
140
160
180
200
0 40 80 120 160 200
Nitrogen Rate, lb N/acre
Co
rn Y
ield
, bu
/acr
e
Grain Yield
Response
EONR = 138 lb N/acre
Yield = 117.7 + 0.8219N - 0.00263N2
a b c
Yield Plateau
Clay 2001 Site -- SC
40
60
80
100
120
140
160
180
200
0 40 80 120 160 200
Nitrogen Rate, lb N/acre
Co
rn Y
ield
, bu
/acr
e
Grain Yield
Response
EONR = 138 lb N/acre
Yield = 117.7 + 0.8219N - 0.00263N2
a b c
Yield Plateau
Clay 2001 Site -- SC
0
20
40
60
80
100
120
140
160
0 50 100 150 200 250N Rate, lb N/acre
$/ac
re
Yield Return to NNet Return to NFertilizer Cost
ISU Agronomy Extension
Calculation of MRTN
3rd - Find the N rate with the greatest average return to N, this is the MRTN and N rate at the MRTN
Return to N at various N rates (lb/acre)Site
71.05
107.01
77.09
85.78
106.56
140
72.0372.4472.9872.5972.0069.24Average
79.2981.3182.3782.3781.3179.203
87.9889.3282.9476.5670.1863.802
108.76110.96113.16115.10115.43113.961
107.25
130
104.96
$/acre
110
102.43
100
106.5798.9894.6092
1209080
Return to N at various N rates (lb/acre)Site
71.05
107.01
77.09
85.78
106.56
140
72.0372.4472.9872.5972.0069.24Average
79.2981.3182.3782.3781.3179.203
87.9889.3282.9476.5670.1863.802
108.76110.96113.16115.10115.43113.961
107.25
130
104.96
$/acre
110
102.43
100
106.5798.9894.6092
1209080
MRTN
ISU Agronomy Extension
Calculation of MRTN
4th - Find the N rates with returns to N within $1.00/acre of MRTN This provides a range of most profitable N rates
Return to N at various N rates (lb/acre)Site
71.05
107.01
77.09
85.78
106.56
140
72.0372.4472.9872.5972.0069.24Average
79.2981.3182.3782.3781.3179.203
87.9889.3282.9476.5670.1863.802
108.76110.96113.16115.10115.43113.961
107.25
130
104.96
$/acre
110
102.43
100
106.5798.9894.6092
1209080
Return to N at various N rates (lb/acre)Site
71.05
107.01
77.09
85.78
106.56
140
72.0372.4472.9872.5972.0069.24Average
79.2981.3182.3782.3781.3179.203
87.9889.3282.9476.5670.1863.802
108.76110.96113.16115.10115.43113.961
107.25
130
104.96
$/acre
110
102.43
100
106.5798.9894.6092
1209080
MRTN
LOW HIGH
ISU Agronomy Extension
Can Examine Different Fertilizer N and Corn Prices
Corn held at $2.20/bu Fertilizer N prices at $0.11, $0.22,
$0.33, and $0.44/lb N Gives N price:corn price ratios of
0.05, 0.10, 0.15, and 0.20
ISU Agronomy Extension
Effect of Price Ratio on Net ReturnIowa - SC
0
20
40
60
80
100
120
140
160
0 50 100 150 200 250
N Rate, lb N/acre
Ret
urn
to
N,
$/ac
re
0.050.100.150.20 HIGH
MRTNLOW
$2.20/bu
$0.11/lb N
$0.22
$0.33
$0.44
ISU Agronomy Extension
Effect of Price Ratio on Net ReturnIowa - CC
0
20
40
60
80
100
120
140
160
0 50 100 150 200 250
N Rate, lb N/acre
Ret
urn
to
N,
$/ac
re
0.050.100.150.20
ISU Agronomy Extension
Potential Iowa N Rate Guidelines Based On MRTN Approach
Previous Crop
Price Ratio
Soybean Corn
LOW† MRTN HIGH† LOW† MRTN HIGH†
$/lb:$/bu - - - - - - - - - - - - - lb N/acre - - - - - - - - - - - - -
0.05 125 145 170 180 200 230
0.10 105 125 145 155 175 195
0.15 90 110 125 140 155 170
0.20 80 95 110 125 140 155
† LOW and HIGH rates approximate the most profitable range for $1.00/acre below and above the MRTN for each price ratio.
ISU Agronomy Extension
Effect of Price Ratio on Expected Corn Yield
Iowa - CC
0
20
40
60
80
100
0 50 100 150 200 250
N Rate, lb N/acre
Per
cen
t o
f M
axim
um
Yie
ld 0.050.100.150.20
IA - SC
0
20
40
60
80
100
0 50 100 150 200 250
N Rate, lb N/acre
Per
cen
t o
f M
axim
um
Yie
ld 0.050.100.150.20
ISU Agronomy Extension
MRTN Rates and N Risk Management
Although you may want to be 100% certain of N sufficiency, being that certain is not most profitable The risk with lower N rates is decreased
profitability due to lost yield The risk with higher N rates is decreased
profitability and environmental concerns due to unneeded N
Most profitable N rate range helps “protect” these risks
ISU Agronomy Extension
Corn Nitrogen Rate Calculatorhttp://extension.agron.iastate.edu/soilfertility/nrate.aspx
Resources
Regional publication
Web based MRTN calculation tool
Concepts and Rationale for Regional Nitrogen Rate Guidelines for Corn
ISU Agronomy Extension
Regional Effort: Participating States and University Personnel:John Sawyer, Iowa State UniversityEmerson Nafziger, University of IllinoisGyles Randall, University of MinnesotaGeorge Rehm, University of MinnesotaLarry Bundy, University of WisconsinBrad Joern, Purdue, UniversityRobert Hoeft, University of IllinoisCarrie Laboski, University of WisconsinRobert Mullen, The Ohio State UniversityRandy Killorn, Iowa State UniversitySylvie Brouder, Purdue University