Corn Starter Fertilizer Phosphorus Source
Comparison
Fond du Lac County (1995 and
1996 results)
Mike Rankin
Crops and Soils Agent
UW Extension - Fond du Lac County
Situation:
Two primary sources of phosphorus fertilizers are sold by area dealers
for corn starter fertilizer applications. These are monoammonium phosphate
[MAP(11-52-0)] and diammonium phosphate [DAP(18-46-0)]. When MAP is used,
ammonuim sulfate (21-0-0 24S) is added to raise the nitrogen component
of the starter nutrient analysis. This also results in a small amount of
sulfur being included. Based on farmer strip trials over past years, some
fertilizer dealers in the area have indicated significant yield gains when
MAP is used as the phosphorus source compared to DAP. The scientific literature
suggests that no yield differences should generally be expected based on
MAP or DAP use, however, many field studies cite broadcast application
comparisons with small grains. There is also some evidence to suggest an
advantage with MAP under high soil pH conditions. Soil pH values of 7.0
or higher are common for many East central Wisconsin soils. The purpose
of this trial is to compare corn grain yields when either MAP or DAP are
used as components of the corn starter fertilizer and to measure the effects
of sulfur as a fertilizer component.
Fertilizer treatments were as follows:
1. DAP (-S) 9-23-30
2. DAP (+S) 8-23-28 3S
3. MAP (-S) 7-23-24
4. MAP (+S) 8-23-24 3S
5. K ONLY 0-0-60
6. CONTROL (NO STARTER)
Site and harvest information:
YEAR: 1995
Location: Larry and Vern Klabunde Farm, Clairville Rd. (N. of
Ring)
Soil Type: Atterberry silt loam
Soil Test: pH=6.9, O.M.=5.7, P=29ppm, K=70ppm, SO4-S=2ppm, SAI=50
Previous Crop: Soybeans
Planting Date: May 17, 1995, JD 7200 Max emerge planter - 6
x 30"
Hybrid: ICI 8751 (95 R.M.)
Fertilizer: - all P-source starter fertilizers blended for 23%
phosphorus (as P2 O5)
- 150 lbs. of starter at planting for all treatments
- 60 lbs. K2O (as 0-0-60) and 100 lbs. of N (as 46-0-0) broadcast over
entire plot (preplant)
Weed control: Broadstrike/Dual PPI (2.5 pts./acre)
Harvest Date: November 3, 1995
Exp. Design: Randomized Complete Block (3 replications)
YEAR: 1996
Location: Roger Clausing Farm, Forest Avenue Road, Rosendale
Soil Type: Lomira Silt Loam
Soil Test: pH=5.6, O.M.=2.0, P=52 ppm, K=144 ppm
Previous Crop: Green peas
Planting Date: May 21, 1996 JD 7000 planter - 6 x 30"
Hybrid: Ciba Max 747 (95 R.M.)
Fertilizer: - all P-source starter fertilizers blended for 23%
phosphorus (as P2 O5)
- 175 lbs. of starter at planting for all treatments
- 150 lbs. N/ac. as 82-0-0
Weed control: Prowl (3 pt./ac.), Accent (.5 oz./ac.), Banvel
(0.5 pt./ac.) - post
Harvest Date: November 7, 1996
Exp. Design: Randomized Complete Block (3 replications)
Results to date:
Two years of comparisons have resulted in no yield differences as a
result of corn starter fertilizer phosphorus source (see table below).
In both years, however, there was a yield advantage to using starter fertilizer
(although not significant in 1996 at the LSD 5% level). There was also
no apparent advantage to having sulfur in the corn starter. This trial
will be continued in 1997.
|
Comparison of MAP and DAP as a corn starter
fertilizer component (Fond du Lac Co.)
|
|
Year
|
|
|
Treatment
|
1995
|
1996
|
Mean
|
|
------------------Yield, bu/acre -----------------
|
|
MAP (+S)
|
116
|
122
|
119
|
|
MAP (-S)
|
119
|
121
|
120
|
|
DAP (+S)
|
120
|
123
|
122
|
|
DAP (-S)
|
120
|
122
|
121
|
|
K ONLY
|
119
|
113
|
116
|
|
CONTROL
|
99
|
117
|
108
|
|
LSD (5%)
|
7.6
|
6.5
|
|
For more information contact Mike
Rankin