Bahan Kajian MK. Manajemen Kesuburan Tanah
MANAJEMEN
NITROGEN
TANAMAN JAGUNG
Smno.agroekotek.fpub.sept2013
Tanaman jagung memerlukan sejumlah besar nitrogen
Proper nitrogen fertilizer
application Good
nitrogen management is
essential for protecting
groundwater quality.
Proper nitrogen
management includes
managing nitrogen rate,
source, timing, and
placement. The primary
goal of nitrogen best
management practices is
attaining high nitrogen
use efficiency.
This assures the most
effective use of nitrogen
fertilizer.
Economic Optimal N Rate (EONR)
The sufficiency range is the nutrient level at which the plant has enough nutrients
to function and develop properly, but not so much that it is poisoned. This is
reported as "medium" or "high" on soil tests.
Yield
Nitrogen Rate
Economic Optimal N Rate (EONR)
Yield
Nitrogen Rate
Economic Optimum Nitrogen Rate
Oran00 Rep1 Block6
Oran00 Rep3 Block26
16
16
12
8
8
Nopt
Yield (Mg ha-1)
Yield (Mg ha-1)
12
4
Nopt
4
0
0
0
100
200
N rate (kg ha-1)
300
0
100
N rate (kg ha-1)
200
300
-1
Economically Optim al N Rate, kg ha
RATE
300
*
250
200
*
* *
150
*
*
*
*
100
350
300
CP00
D L00
MD00
CP01
DL01
MD01
DL02
MD 02
250
EONR (lbs N/acre)
200
150
100
50
0
0
50
100
150
200
Sensor N Rate with MO Algorithm (lbs N/acre)
250
EONR (lbs N/acre)
250
200
150
100
50
0
0
50
100
150
200
250
Sensor N Rate with MO Algorithm (lbs N/acre)
B
C w/o
C with
D
H
P
S
W
EONR (lbs N/acre)
250
200
150
100
50
0
0
50
100
150
200
250
Sensor N Rate with MO Algorithm (lbs N/acre)
C w/o
C with
P
W
EONR (lbs N/acre)
250
200
150
100
50
0
0
50
100
150
200
250
Sensor N Rate with MO Algorithm (lbs N/acre)
B
D
H
S
1. EONR prediction is not easily accomplished,
and is more of a challenge in rainfed
environments.
2. If one could reliably predict yield, this factor
alone does not do a good job of predicting
EONR.
3. In 2004 and averaged over all sites, we achieved
~$5/acre more profit when using the sensors
when compared to the farmer’s single blanket
rate. (average of 30 lbs/acre less N).
4. Data needs to be collected to test current and
yet-to-be developed algorithms.
Research supported in part by the USDA- NRI, IFAFS, and CIG Grant
Programs. Assistance also given by OSU, NTech, and Holland Scientific
Instruments.
N Recommendation for corn
The corn N recommendations are based on:
- Yield potential
- soil type and drainage
- Soil N supply
- soil type and drainage
- N fertilizer uptake efficiency
- soil type and drainage
- N credits from sods
- % legume/grass in the sod
- N credits from manure
- application method + timing
Cornell Corn N Recommendations
in bushels/acre
in lbs N/acre
(yield potential * 1.2) – soil N – sod N
N requirement =
(fertilizer efficiency/100)
in lbs N/acre
in %
- soybean N or manure N credits
= soil series specific
Initial Field Calibration
400
NONRESPONSIVE
350
Critical
Values
-1
ISNT-N (mg kg )
300
250
200
RESPONSIVE
150
y = 126.36 + 4.0944x - 0.0199x 2
100
2
r = 0.9851; n = 33
50
0
0
20
40
60
80
-1-1
Organic matter
kg
Loss-on-ignition
(g(gkg
))
100
120
Factors relating to BMP’s for N
1. Cropping
systems
2. N rate applied
3. Time of
application
4. Nitrification
inhibitors
5. N source
6. Tillage
7. Cover crops
Established Gliricidia-maize intercropping system in
Southern Malawi. Photo: T. Breedy
http://climatecolab.org/plans/-/plans/contestId/18/planId/1304331
CROPPING SYSTEMS
http://www.cirad.fr/en/research-operations/research-results/2009/no-tillage-with-cover-crops-for-thebrazilian-cerrados
Effect of CROPPING SYSTEM on drainage volume, NO3-N concentration,
and N loss in subsurface tile drainage during a 4-yr period (1990-93) in
MN.
Cropping
System
Total
Nitrate-N
discharge
Conc.
Loss
Inches
ppm
lb/A
Cont. Corn
30.4
28
194
Corn – Soybean
35.5
23
182
Soybean – C
35.4
22
180
Alfalfa
16.4
1.6
6
CRP
25.2
0.7
4
Nitrate losses in tile drainage water from soil
mineralization.
50
Established grass
F-W Nitrate-N Conc. (ppm)
60
40
30
20
10
Dry years
0
87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04
Year
Cropping
system has
greater effect on
hydrology and
nitrate losses
than any other
management
factor!
Cumulative Nitrogen Uptake Across the
Growing Season
“Preventive
Management”
http://www.lenrd.org/nitrogen-management/
RATE OF APPLICATION
1.
2.
3.
4.
Good nitrogen management requires
understanding:
How nitrogen is used by the crop
When nitrogen is used by the crop
What environmental influences affect the use of
soil and fertilizer nitrogen by the growing crop
How management of nitrogen and irrigation
water affect the leaching of residual nitrate,
which eventually affects water quality
http://www.lenrd.org/nitrogen-management/
Continuous Corn, 2001–03 Olmsted Co.
Effect of N rate for corn after soybean on NO3-N
concentrations in tile drainage water in 2001.
40
80 lb N/A
120
160
30
25
20
15
Date
24
-J
un
17
-J
un
10
-J
un
un
3J
13
-M
ay
20
-M
ay
27
-M
ay
6M
ay
r
29
-A
p
r
22
-A
p
r
10
15
-A
p
Nitrate Conc (mg/L)
35
Effect of N rate on yield of corn after soybean, net return to
fertilizer N, and nitrate-N concentration in tile drainage at
Waseca (2000–2003).
N Treatment
4-Yr Yield Net
4-Yr FW
Time Rate N-Serve
Avg.
Return NO3-N conc.
lb /A
--0
Fall
80
“
120
“
160
Spr. 120
--Yes
“
“
No
bu/A
111
144
166
172
180
$/A/Yr
--30
70
78
105
mg/L
--12
13
18
14
Effect of N rate applied for corn in 2003 on nitrate-N
concentration and loss in tile drainage during May–
September 2004 from soybeans at Waseca.
N
Rate.
Lb/A
FW Nitrate-N
Concentration
mg/L
Nitrate-N
Loss
Lb/A
80
120
160
9
12
20
36
52
81
Conclusion
1. Corn yields were increased 5% and nitrate losses
in drainage were reduced by 27% when reducing
the N application rate from 160 lb/A applied in the
fall to the recommended 120-lb rate applied in the
spring.
2. Reducing the N rate from 120 lb/A to 80 lb/A
reduced yield by 17% and nitrate loss by 13%.
3. Forty-six percent of the nitrate lost in tile
drainage from a corn-soybean rotation was lost
in the year soybeans were grown.
TIME OF N APPLICATION
Maximum nitrogen
uptake occurs
in periods of maximum
growth (in
corn roughly between
vegetative
growth stages V9 and
V18, or from hip-high
to just before
tasseling).
Risk of N loss is low
during this period.
Credit: Iowa State
University Extension.
http://plantsci.missouri.edu/nutrientmanagement/nitrogen/practices.htm
Effect of time of N application and N-Serve on corn yields
after soybean from 1987–2001 at Waseca.
Parameter
15-Yr Avg. Yield (bu/A)
15-Yr Avg. Economic return
over fall N ($/A/yr) *
7-Yr Avg. Yield (bu/A) **
7-Yr Avg. Economic return
over fall N ($/A/yr) *
Time of N Application
Fall Fall+N-Serve Spring
144
153
156
--$9.30
$18.80
131
---
146
$22.50
* Corn = $2.00/bu; N = $0.25/lb N
** Seven years when statistically significant differences
occurred.
158
$51.00
Nitrate-N concentration in tile drainage from a corn-soybean
rotation as influenced by time of N application and N-Serve at
Waseca.
N Treatment
Time of application
N-Serve
Nitrate-N Conc.*
-- mg/L --
Fall
No
14.1
Fall
Yes
12.2
Spring
No
12.0
* 10-cycle (1990-2000) rotation average.
1999 tile water NO3-N loading at Waseca vs. NO3-N
concentrations in the Le Sueur River 2.3 miles from Mankato.
60
18.0
15.6
15.2
16.0
14.1
40
12.7
12.0
30
14.0
11.9 11.6 12.0
10.8
20
10.0
10
Fall AA
PP AA
Le Sueur River
7.4
8.0
Sampling Date
-J
un
30
-J
un
23
-J
un
16
n
Ju
9-
n
Ju
2-
-M
ay
26
-M
ay
19
-M
ay
12
ay
M
5-
pr
-A
28
pr
-A
21
pr
-A
14
7-
Ap
r
6.0
-M
ar
0
Nitrate-N (ppm)
16.2
15.7
50
31
Nitrate-N Loss (lb/A)
16.6
Conclusion
• Compared to late fall N application without
N-Serve over the 15-year period:
– Corn yields were increased 9 and 12 bu/A/yr
(6 and 8%) by either fall N+N-Serve or spring
preplant N, respectively.
– Nitrate losses were decreased 14 and 15% by
either fall N+N-Serve or spring preplant N,
respectively.
Proposed BMP’s for South-Central MN
• Recommended
– Spring preplant or split applications of
ammonia, urea, or UAN are highly
recommended.
– Incorporate broadcast urea or preplant UAN
within three days.
– Apply sidedress application before corn is
12” high.
– Inject or incorporate sidedress applications
of urea or UAN to a minimum depth of 4
inches.
Proposed BMP’s for South-Central MN.
• Recommended, but with greater risk
– Fall application of AA + N-Serve after soil
temperature at 6-inch depth is below 50° F.
– Side dressing all N before corn is 12 inches
high.
• Not recommended
– Fall application of urea, UAN, or anhydrous
ammonia without N-Serve
Economic Nitrogen
Management for Corn
“NEW”
MSU N Recommendations
How much is enough?
• Old vs. new recommendations…
Yield vs. Economic Return
– Old:
• 1.2 lbs per bushel
• This only applies within yield potential of soil
– New:
• Based on economic return
• This only applies within yield potential of soil
• Use previous crop in association with field history
(low – medium – high – very high)
Definitions
•
•
•
•
MRTN – maximum return to N
EONR – economic optimum N rate
N:Corn Price Ratio
Corn Yields – 5 year averages – soil
productivity (disregard unusual hi’s or lo’s)
– Low: Average yield , <120 bu/a
– Med: Average yield, 121 – 150 bu/a
– High: Average yield, 151 – 180 bu/a
– Very High: Over 181 bu/a
Response Data Model Fit
Yield (bu/acre)
Optimum Maximum
N rate (lb/acre)
Critical value or range indicates the soil or tissue content below which the plant
most likely is deficient in that specific nutrient and production could be enhanced
by addition of the nutrient. Below that critical value, the nutrient levels are below
optimum.
http://nrcca.cals.cornell.edu/nutrient/CA3/CA0323.php
Luxury consumption occurs when soil nutrient levels are above optimum and
plants take up more of a nutrient than needed for functioning and production.
Potassium (K) is commonly taken up in excess.
http://nrcca.cals.cornell.edu/nutrient/CA3/CA0323.php
How much is right?
• National Corn Growers Contest (NCGA):
• 10 separate yield checks averaged:
– 163.1 lbs of N/acre (131-210)
– Average yield = 214.5 bu/acre (181-239)
– .76# N/bu (.57 - .95)
• Was it economical????
• It depends…………
Key points…
• Determine soil productivity…a 5 year history.
• Determine N:Corn price ratio
• Evaluate crop conditions, and weather at the
time of maximum N application.
– This could be at planting or at sidedress
time.
Criteria for Soil Productivity or
Yield Potential Grouping
1. Low:
2. Medium:
≤ 120 bu/a
121 – 150 bu/a
3. High:
4. Very High:
151 – 180 bu/a
≥ 181 bu/a
5. 5 year running average!
Soil Yield Potential
• Qualitative assessment of soil productivity
– Group soils with similar N response
• Tiled, non-tiled, high OM, etc.
– Do Not use yield estimate to calculate N rate
• Based on soil series description
• Look at:
– Water holding capacity
– Drainage class
– Depth of root zone
– Length of growing season (> or < 2300 GDD)
N response functions
12
Corn following Corn
241
10
185
-1
Grain Yield (Mg ha )
11
9
8
134
7
6
High/Very High Yield Potential
Medium/Low Yield Potential
Irrigated Sand
5
4
3
0
50
100
150
200
Nitrogen Rate (kg N ha-1)
250
Example # 1
1.
2.
3.
4.
5.
6.
Heavy clay soils
Non-tiled
118 bu. average
Corn price $3.12
N price (28%) $385/T
Previous crop soybeans
• N:Corn Ratio = .22
• Crop condition –
excellent
• Soil Moisture –
excellent
• Population 32,000/a
• Recommendation:
80 Lbs. added N/a
range 65 – 95 lbs/a
Example # 2
1.
2.
3.
4.
5.
6.
Sandy loam soils
Tiled
167 bu. average
Corn price $4.04
N price (28%) $365/T
Previous crop
soybeans
1. N:Corn Ratio = .16
2. Crop conditions –
excellent
3. Population – 32,000
4. Soil moisture –
very good
5. Recommendations:
105 lbs. added N
range of 90 -120 lbs/a
0
40
80
120
Lbs. of sidedress N applied
160
MRTN Plot – St. Clair County
Starter
N
Sidedress
N
Total
N
%
Moisture
38
0
38
22.6 c
149.07 c
38
38
40
80
78
118
21.6 b
21.4 b
195.95 b
201.49 b
38
120
158
20.9 a
215.93 a
38
160
198
20.5 a
218.25 a
Adj. Yield
Previous Crop – Soybeans ~ 30 lb credit
0.83
LSD
10.9
2.06%
C.V.
3.05%