Riverland Community CollegeDecember 6, 2006
Lynn Lagerstedt
• Paying attention to detail
Many fields with headlands stronger than the field.
Why?
N Price/CropValue Ratio
corn/corn corn/soybeans
MRTNacceptable
range MRTNacceptable
range
-----------lb N/acre--------
0.05 155 130 to 180 120 100 to 140
0.1 140 120 to 165 110 90 to 125
0.15 130 110 to 150 100 80 to 115
0.2 120 100 to 140 85 70 to 100
*MRTN= Maximum Return To Nitrogen
University of Minnesota Nitrogen Suggestions
Corn producers at 143 sites compared normal rate of Nitrogen to 50 lb N/acre less in replicated two-treatment precision farming trials that covered at least 20 acres
Fertilizer N usually was applied shortly before or after planting
All fields were corn following soybeans
Information from the Iowa Soybean Association
Summary of trials by year
March-May Fertilizer N Yield
Year Rainfall Low Rate High Rate Low Rate Response
2000 7.5 119 169 157 2
2001 11.3 102 152 169 3
2002 8.5 96 148 189 7
2003 9.8 98 153 179 4
2004 14.4 99 143 195 13
2005 8.6 95 147 177 8
Mean 10.8 100 149 178 8
FORM:
1. Commercial nitrogen source at discretion of
producer
2. All nitrogen sources (ex. MAP, DAP, liquid starters,
etc.) must be accounted for in final nitrogen
application rates
3. Anhydrous ammonia only for fall applications
Guidelines for Minnesota Nutrient Management Initiative
TIMING AND PLACEMENT:
4. A farm can have a fall-applied site, a spring-applied
site, or split application site but not in combination
within the same site. Timing will be held constant
across a site relative to season of application.
5. Fall AA applications will be delayed until the soil
temperature remains below 50° F at 6-inch depth
Guidelines for Minnesota Nutrient Management Initiative
TIMING AND PLACEMENT (cont):
6. Use a nitrification inhibitor with fall and pre-plant
nitrogen applications if soils poorly drained and soil
moisture levels are high near the surface
7. Side-dress application before corn reaches a 12
inch height
8. If split applications – one of the applications must
be of equal rate over entire demonstration site
9. Spring pre-plant Urea and/or UAN applications
incorporated within 3 days on NRCS strips
Guidelines for Minnesota Nutrient Management Initiative
• Conducted by the University of Minnesota in Fillmore County
N Treatment
lb/Acre
0
30
60
90
120
150
180
30+60*
LSD (0.10)
Corn Yield
Bu/Acre
135.2
155.3
186.0
194.8
199.6
204.5
206.5
185.8
12.7
*30 lb N/A preplant as urea plus 60 lb N/A sidedressed with UAN at V6 stage
• High organic matter soils
– Nitrogen as Anhydrous Ammonia Spring pre-
plant or sidedress produced good results with
100 lbs actual Nitrogen
– Urea at 100lbs N/acre resulted in N deficiency
• Low organic matter soils
– Anhydrous Ammonia at 100 lbs/acre resulted in
N deficiency
RateYield
(bu/acre)
Check (0 lbs K20/acre) 136.5
Broadcast(105 lbs K20/acre) 157.7
Starter (42 lbs K20/acre) 180.3(100 lbs/acre, 5-14-42)
LSD (0.10) - 11.02
CV% 4.0
K soil test preplant: 65 ppm
Joy silt loam
Planted 4/28/97 - 30,000 seeds/acre - 3 reps
Tim Wager, Area Extension Educator
148
148
134
Top 2 Inches
Middle 2 Inches
Bottom 3 Inches
Yo
ur
So
il
Potassium Availability
V. Low<60
Low61-90
Med91-120
High121-150
V. High>150
History of Moldboard Plow
120
88
55
Top 2 Inches
Middle 2 Inches
Bottom 3 Inches
Yo
ur
So
il
Potassium Availability
V. Low<60
Low61-90
Med91-120
High121-150
V. High>150
• Weed resistance to herbicides• Weed adaptation• Shift in weed species
How important is it to rotate herbicides?
• Woolly Cupgrass– Reduced rate of soil-applied grass
herbicide followed by a reduced rate of Accent/Steadfast
Corn weed control programs that work
• Giant Ragweed– 2,4-D at a low rate when corn is spike to
2-leaf, followed by a planned broadleaf herbicide
Corn weed control programs that work
• Soil applied herbicide followed by post-emergence herbicide– DNA (Treflan, Prowl)
– Boundary (Dual, Sencor)
– Authority•Is it available?
Soybeans
• Phytophthora Root Rot
• Soybean Cyst Nematode
• Anthracnose
• Brown Stem Rot
• White Mold
• Sudden Death Syndrome (SDS)
• Asian Rust
• Top 5 in Average Yield
1. Dekalb 51-45 209.5 bu/ac
2. Garst 8745 207.9 bu/ac
3. LG Seeds 2533 206.3 bu/ac
4. Crows 4S502 204.6 bu/ac
5. Dekalb 52-47 203.2 bu/ac
• Top 5 in Return over Drying Cost
1. Dekalb 51-45 $602.52/ac
2. Garst 8745 $602.20/ac
3. Crows 4S502 $591.66/ac
4. Dekalb 52-47 $587.77/ac
5. Dekalb 46-26 $586.39/ac
• Top 5 in Return over Seed and Drying
Cost
1. Garst 8745 $548.20/ac
2. Dekalb 46-26 $539.23/ac
3. Dekalb 51-45 $537.36/ac
4. AgVenture 5544 $528.99/ac
5. Renk 772 $528.72/ac
• Average Yield
1. Dekalb 51-45
2. Garst 8745
3. LG Seeds 2533
4. Crows 4S502
5. Dekalb 52-47
• Return over Drying &
Seed
1. Garst 8745
2. Dekalb 46-26
3. Dekalb 51-45
4. AgVenture 5544
5. Renk 772
(13)
(6)
(8)
(10)
(6)
(7)