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Managing N usingThe Illinois Soil Nitrogen Test
Tim SmithCropsmith Inc.
Nitrogen Testing, Consulting
Don’t be mislead focus on what is important
Why all the interest in nitrogen?
• For Nitrogen Rates 140 lbs to 220 lbs• 140-220 lbs NH3 spring 08 $60.20-94.60• 140-220 lbs 28% Solution Spring $84.00-132.00
• For each 10 lbs of NH3 saved $4.50
• For each 10 lbs of 28% saved $6.00
Year of University Research Shows
60-90% of Crop N comes from soilFertilizer needed to supplement soil N
typically ranges from 80 to 220 lbs of N Variable Rate Nitrogen is about redistribution
of N from where less is need to where more is needed.
How much N do you need?
Yield 126
Yield 227
0
N Rate
210lb
N
On-Farm trial Champaign
County Illinois 2003
How little N do you need?
Yield 177
Yield 193
On-Farm trial Champaign
County Illinois 2003
0
N Rate
210lb
PY Rate 192 lbs N
At today's NH3 prices each bushel gain cost $5.16 in N
Corn yield at the zero-N rate as a percent of yield at EONR.
Previous Crop
State Corn Soybean
---------- % -----------
Illinois 54 64
Iowa 45 75
Minnesota 60 76
Wisconsin 75 80
Economic Optimum Nitrogen Rate
• EON is the rate of applied N where the last dollar of your N cost returns more slightly more than a dollars worth of grain. With more N than the economic rate you may get more yield but you will earn less money.
IPNI Crop Nutrient Response tool
• How can you determine Economic Optimum N Rate?
Example of Nitrogen Response Trial
20080120400
016020012080
12040801600
160 40 200
The Closer to the Economic N Ratethe more money you make
Cost of Over and Under Application Of N
101.0
46.0
30.8
53.3
20.7
36.9
0.0
20.0
40.0
60.0
80.0
100.0
120.0
Over Under Over Under Over Under
Illinois Soil Nitrogen Test MRTN Proven Yield
lbs over or under
Ave
rag
e lb
s o
ver
un
der
Corn @ $4.80/buN fert @ .48 cents/lb
$13.63
$2.88
$25.20
$10.48
$48.00
$23.13
Within $8 of best N rate
$26.70 from best N rate
Cropsmith Recommendation
University Recommendations
Why Soil Based N Management?
• If soils differ in there response to N, them so should our management of them.
• The soil supplies a majority of the nitrogen that plants take up during growing season.
• Other solutions (such as Greenseeker) exist but may have limited acceptance due to logistics.
What is the Illinois Soil Nitrogen Test?
• This New test Developed at the University of Illinois measures potentially available nitrogen that is released from the organic matter in the soil
What kind of nitrogen release do your soils have?
IPNI-Crop Nutrient response tool
EON 130 lbs N EON 180 lbs N
Both fields yielded 200 bushels
Is the Economic N Rate Stabile Year to Year?
Jack Meisinger InfoAg presentation 2007
ISNT Soil Test Map
Cropsmith Variable Rate Application Map
Results from 2007
ISNT 175-225 ISNT 270-304
Corn $3.35 Fert. N $.50
MRTN Recommendation 147lbs N
2007 ISNT Values
2007 ISNT Nitrogen Recommendations
2007 Results
ISNT 175-225 ISNT 270-304
Corn $3.35 Fert. N $.50
MRTN Recommendation 147lbs N
How much N do you need?
Soil Test ISNT 192 PPM
Experimental Best N Rate 180 lbs
Yield 126
Yield 227
0
N Rate
210lb
N Rate
Cropsmith Recommendation
169 lbs N
On-Farm trial Champaign
County Illinois 2003
How little N do you need?
Yield 177
Yield 193
On-Farm trial Champaign
County Illinois 2003
Soil Test ISNT 225 PPM
Experimental Best N Rate 126
Cropsmith Recommendation
147 lbs N
58 Plots in Illinois from three years
For every .45 lb of N increase, Yield increases 1 bushel
For every 350 plant increase, Yield increases 1 bushel
(.45 * lbs of N )+ (.0035 * population) = Yield
.45* 188# N+ .0035*31236 plants = 192 bu/AActual yield 188 bu/a
Why haven’t nitrogen soil tests worked?
• Past soil test have measured Nitrates which are not stable in the soil.
• ISNT measure the part of organic matter with is one source of nitrate in the soil.
Fertilizer N
Organic Matter
Or maybe old ones
Sources of N to Plants
Fertilizer N –Less Efficient
Organic Soil N –More Efficient
How much N does your corn crop need?200 lbs corn
• Corn takes up 1.1 lb of N per bushel yield• Corn removes from field only .68 lbs N per bu.
• 200 bushel would take up 220 lbs of N • 200 bu corn would remove 136 lbs of N
• 75% of N comes from soil (organic N)
• Applied N is only 40% efficient
• 220 lbs N needed 165 from soil 55 needed from Fertilizer• 137 lbs of Fertilizer N needed
• 83 lbs of N in corn stover left to be recycled ( organic N)
How much N does your corn crop need?150 bu Corn
• Corn takes up 1.1 lb of N per bushel yield• Corn removes from field only .68 lbs N per bu.
• 150 bushel would take up 165 lbs of N • 150 bu corn would remove 102 lbs of N
• 50% of N comes from soil (organic N)
• Applied N is only 40% efficient
• 165 lbs N needed 82 from soil 82 needed from Fertilizer• 205 lbs of Fertilizer N needed
• 63 lbs of N in corn stover left to be recycled (organic N)
N cycle
50-90%
10-50%
Top Ten Important Nitrogen Factors
1. Amount of N from soil2. Rotation-amount, type of residue from previous crop3. Population of current crop4. Weather (moisture, temp, timing)5. Source and timing of N6. Hybrid response to N7. Past N applications (especially from manure)8. Drainage 9. pH and nutrient levels Nutrient interactions P, K and S10. Cost of N, Price of Crop
17 Sites Indiana
With x-int estimate of soil N
0
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150 200 250 300 350 400
Total N supply, lb/a
Rel
ativ
e yi
eld
100 to 140 bu/a 141 to 180 bu/a 181 to 220 bu/a
Purdue (Camberato, Nielsen)
Corn after Soybeans 2005
190 Acre field in McLean County (C.U. Williams Farm)Average yield 189 bu.
Ave.135 lbs of N Yield 189 Bushel
Average N Rate 146# N
Soil is more efficient at delivering N to plants
Yield by N Rate and ISNT
170
175
180
185
190
195
200
205
210
215
220
90 110 120 130 150 180 210
N Rates
Yiel
d
ISNT>300
ISNT280
ISNT260
ISNT240
ISNT220
ISNT200
ISNT<180
U of I C.U. Williams Field 2006
Ave yield 191.3 bu.
• Green test strips 165 lbs N
• Increased N in test strips marginally increased yield in some places
How and when to sample
• We sample 0-12 an 12-24 inches deep
• Sample can be taken Fall, Winter, Early Spring
• Maps can be used for 6-8 years
• Sample have some special handling requirements
Cost of Nitrogen Soil Testing
• We have complete programs from $8.30 to $15 per acre
• For $8.30 you get whole field N rates with two zones per field
• $15 includes intensive sampling 0-12 and 12-24 inch at all sample sites and complete variable rate recommendations
Conclusions
• Having an ISNT map of your field can save money maintain high yield for many years
Cropsmith IncTim Smith
(217) [email protected]
www.cropsmith.com
Fall 2007 results
Yield by N Rate
Cs Nrec
Avg Corn
12
01
99
12
02
11
12
02
13
12
02
04
14
02
05
16
02
05
12
02
11
60
21
1
0
50
100
150
200
250
120 120 120 120 140 160 120 60
2006 DataNorthern and Central Illinois
Corn Soybean Rotations
y = -0.5883x + 285.87
R2 = 0.5221
100
120
140
160
180
200
220
240
100 120 140 160 180 200 220 240 260 280 300
ISNT
Eco
no
mic
O
pti
mu
m N
175 N
192
2006 DataNorthern and Central Illinois
Corn Soybean Rotations
y = -0.5883x + 285.87
R2 = 0.5221
100
120
140
160
180
200
220
240
100 120 140 160 180 200 220 240 260 280 300
ISNT
Eco
no
mic
O
pti
mu
m N
155 N
225
What kind of nitrogen response does your soils have?
Southern Illinois
Economic N Rate 192
ISNT 95
Central Illinois
Economic N Rate 124
ISNT 265
QP EON vs MRTN 06 from N Rate Calc.3 outliers removed
y = -0.5343x + 244.93
R2 = 0.076
0
50
100
150
200
250
300
0 50 100 150 200 250
MRTN from N Rate Calc.
QP
EO
N
3 Outliers Removed one each , Rotation, Variability, Flooded field
CC
N
orth
CS
B N
orth
CC
Central
CS
B S
outhC
SB
Central
Nafziger 2006 MRTN