Soybean Iron Chlorosis Project 2001 Summary Report AGVISE Laboratories Benson, MN & Northwood, ND

Soybean Iron Chlorosis Project2001

Summary Report

AGVISE LaboratoriesBenson, MN & Northwood, ND

Soybean Iron Chlorosis ProjectOverview

In cooperation with many of our customers, AGVISE Laboratories conducted a soybean iron chlorosis project in the summer of 2001 throughout the tri-state areas of MN, ND and SD. Sample locations were selected based upon chlorosis hot spots in grower fields throughout the region. Three soil samples were collected in each field, representing normal (healthy) soybean growth, moderately affected areas and a severely affected area. Only the severe and normal areas will be compared in this summary. Lab analysis consisted of measuring soil pH, carbonates and soluble salts. Field information included location, variety, plant height at time of sampling, date sampled, crop color, presence or absence of SCN on roots and row spacing. This summary will only look at plant height, pH, soluble salts and carbonates.

Summary1. Plant Height: Dramatic

difference between chlorotic and healthy areas.

2. Soil pH: No difference between chlorotic and healthy areas.

3. Soluble Salts: Major factor in contributing to soybean iron chlorosis.

4. Carbonates: Major factor in contributing to soybean iron chlorosis.

5. Note: SCN was a non-factor in the vast majority of fields sampled.

25

5.4

0.4

7.96

10

0.7

8

0

5

10

15

20

25

Healthy Severe

Plant Ht.(inches)CCE (%)

Salts(mmhos/cm)pH

Soybean Iron Chlorosis ProjectSummer 2001: Agvise @ Benson, MNFields Sampled: 79Locations: 76 from S. MN, 3 from SD

16

1.9

0.4

8 7.5

5.7

1

8

0

2

4

6

8

10

12

14

16

Healthy Severe

Plant Ht.(inches) CCE (%)

Salts(mmhos/cm)pH

Soybean Iron Chlorosis ProjectSummer 2001: Agvise @ Northwood, NDFields Sampled: 26Locations: 15 ND, 7 MN, 3 SD

Average Plant Heightat Sampling Time

25

6

0

5

10

15

20

25

Healthy Severe

Height (inches)

Soybean Iron Chlorosis ProjectSummer 2001: AGVISE @ Benson, MNFields Sampled: 79Locations: 76 from S. MN, 3 from SD

Average Plant Heightat Sampling Time

16.4

7.5

0

2

4

6

8

10

12

14

16

18

Healthy Severe

Height (inches)

Soybean Iron Chlorosis ProjectSummer 2001: AGVISE @ Northwood, NDFields Sampled: 26Locations: 15 ND, 7 MN, 3 SD

Average Carbonate (CCE)

5.4

10

0123456789

10

Healthy Severe

CCE (%)


Average Carbonate (CCE)

1.9

5.7

0123456789

10

Healthy Severe

CCE (%)


Average Soluble Salts

0.4

0.7

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Healthy Severe

Salts


Average Soluble Salts

0.4

1

00.10.20.30.40.50.60.70.80.9

1

Healthy Severe

Salts


Average pH

7.98

7

7.5

8

Healthy Severe

pH


Average pH

88

7

7.5

8

Healthy Severe

pH


Summary of the 2001Soybean Iron Chlorosis Project

AGVISE Labs, Benson, MN

• Fields Sampled: 79 – 76 from Southern Minnesota– 3 from South Dakota

• Plant Height Averages– Severe Chlorosis: 6 inches– Healthy: 25 inches


AGVISE Labs, Northwood, ND

• Fields Sampled: 26 – 15 from North Dakota– 7 from Northwest Minnesota– 3 from South Dakota

• Plant Height Averages– Severe Chlorosis: 7.5 inches– Healthy: 16.4 inches

• pH:– Severe Chlorosis: 8.0– Healthy: 7.9

• Range of pH’s– Severe Chlorosis: 7.5 to 8.4– Healthy: 6.5 to 8.4



• pH:– Severe Chlorosis: 8.0– Healthy: 8.0

• Range of pH’s– Severe Chlorosis: 7.9 to 8.3– Healthy: 6.8 to 8.3



• Soluble Salts– Severe Chlorosis: 0.7 mmhos/cm– Healthy: 0.4 mmhos/cm

• Range of Salts– Severe Chlorosis: 0 – 3.4 mmhos/cm– Healthy: 0 – 1.7 mmhos/cm



• Soluble Salts– Severe Chlorosis: 1.0 mmhos/cm– Healthy: 0.4 mmhos/cm

• Range of Salts– Severe Chlorosis: .30 – 2.45

mmhos/cm– Healthy: 0.1 – 0.9 mmhos/cm



• Carbonates (CCE) – Severe Chlorosis: 10%– Healthy: 5.4%

• Range of Carbonates– Severe Chlorosis: 0.1 – 21%– Healthy: 0 – 20.5%



• Carbonates (CCE) – Severe Chlorosis: 5.7%– Healthy: 1.9%

• Range of Carbonates– Severe Chlorosis: 0.4 – 13%– Healthy: 0 – 11.7%




AGVISE Labs, Benson, MN Locations by County

• Blue Earth• Brookings (SD)• Brown (SD)• Chippewa• Cottonwood• Douglas• Grant• Kandiyohi• Lyon• Nicollet

• Ottertail• Pope• Renville• Sibley• Stearns• Stevens• Swift• Traverse• Yellow Medicine

33%24%8%3%2%

3% 3%6%

13% 56%

35%

26%

12%

11%2%

3%

% of Samples With Carbonates >5.0%

3%

(8600 Samples Tested in Highlighted Areas, Fall 2001)

97%80%77%54%70%

57% 32%44%

69% 92%

62%

40%

16%

28%20%

18%

% of Soil Samples With Soil pH >7.3

25%

(97,000 samples tested for pH in highlighted areas)

Interpretation for Carbonates & Salts

• Point Samples– If salts is higher than 0.7 and carbonate is higher

than 5.0%, severe chlorosis is likely in that point.

• Composite Field Sample– If salts are higher than 0.4 - 0.7 and carbonate is

higher than 2.5-3.0%, areas of the field are likely to have chlorosis.

“Higher Salt Level”

Interpretation for Carbonates & Salts

• Point Samples– If salts is less than 0.4 and carbonate is higher

than 8.0%, chlorosis is likely at that point.

• Composite Field Sample– If salts are less than 0.4 and carbonate is higher

than 5.0%, areas of the field are likely to have chlorosis.

“Low Salt Levels”

Future of Carbonate and Salt Soil Test

•Seed companies testing their variety plots

•Varieties rated by carbonates & salts

•Information used for better management

•Diagnostic tool to investigate spots in fields

•Variety selection

Factors “Known” to Increase Potential for Iron Chlorosis

•Soluble Salts

•Carbonates

•Excessive water

•Cool Temperatures

•High pH???????

Iron Chlorosis Facts• Carbonates and Salts are two important factors

affecting potential for iron chlorosis.• Carbonates are a fixed soil property• Salts can be reduced with drainage• Soil pH is not a good indicator of potential iron

chlorosis.• Knowing the carbonate and salt level can help

growers choose fields to plant soybeans.• Knowing the carbonate and salt level can help

explain problem areas.

Documents

Soybean Iron Chlorosis Project 2001 Summary Report AGVISE Laboratories Benson, MN & Northwood, ND