Corn and Soybean Management Issues

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

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