Supplemental Sulfur in Soybeans Two Years Data

from NW MN

Research Progress ReportAlerus Center - 12/13/18

Research Team• Dr. Nancy Ehlke - Overall project lead and

trial design and data analysis• Donn Vellekson - U of MN Mag Farm

manager, field layout and data collection • Dave Grafstrom - Coordinate day-to-day

activities in small plot and large on-farm trials

• Summer intern/s assist in data collection

Research Question and Project Objectives

• Do soybeans respond to supplemental sulfur in the soils of NW MN?

• Conduct small plot replicated trials with 15 and 30 #’S/ac applied broadcast (PPI) and down the tube (IF) at planting

• Conduct large plot trials with two treatments applied broadcast (PPI)– 26-0-0– 26-0-0-30s

Departure from Normal Temps

Roseau - 2017 Roseau - 2018

Average Rainfall in April -August Compared to 2017

0

1

2

3

4

5

6

April May June July Aug

Rainfall in Inches Average

2017

Rainfall at U of MN, Mag Farm from April to Sept in 2018

0

0.5

1

1.5

2

2.5

3

3.5

4

April May June July Aug Sept

Rainfall - Inches Average

2018

Growing Season Recap2017

• Limited winter snowfall • Below average rainfall• Cool dry spring &

summer• Average soybean yields • Limited disease & aphid

expression

2018• Limited winter snowfall• Below average rainfall• Cold spring• Warm summer• Above average soybean

yields• Below average white

mold and aphid expression

Sulfur in Soybeans – Should we be Concerned?

• 1990 Clean Air Act - 77% reduction of sulfur in acid rain in the last 27 years

• Sulfur is an essential element and plays an important role in protein synthesis in plants

• Sulfur soil test is non-diagnostic• Response to sulfur fertilization depends on soil

mineralization, cool and/or dry conditions less microbial activity

• Increased observations of sulfur deficiency in field crops, especially light textured soils with <3% OM

• Sulfur deficiencies cause yellowing of plant tissue

25%

25%30%

29%30%

58%

74% 40%

26%

26%

17% 9%

20%

6%21%

30%29%

% Soil Samples with %OM less than 3.0%

Fall 2017 Samples(0-6” samples)

MB

ND

SDMN

7%

4%

11%

76%

43%

20%6%28%

26%

24%

50% 13%25%

3%

6%7%

14%29%20%

36% 11%

27%

7%

4% 3%

2%

2%

5%5%

9%5%

% Soil Samples with Sulfur less than 15 lb/a

Fall 2017 samples(0-6” samples)

MB

ND

SDMN

13%

80%73%

89% 79%

77%

19%

59%

55%

40%

32%

49%

48%

Sulfur – What do We Know?

Sulfur in Plants• Essential element• Mobile in soil (leach in

sandy soils)• Not mobile in plant as

symptoms appear on upper part of plant

• Two Amino Acids contain sulfur – Methionine– Homocysteine

Sulfur Deficiency

Project Scope

• Small plot replicated research trials

• U of MN Magnusson Research Farm

• Large on-farm trials • Partnerships with

local agronomists and crop consultants

Sulfur (AMS) Treatments in Soybeans

Large Plot• Two Treatments

– 26-0-0– 26-0-0-30S

Small Plot• Five Treatments• None• 15# S - B• 15# S - IF• 30# S - B• 30# S - IF

Materials & Methods 2017

Small Plot Trial• Previous crop - Wheat• Seeding date: 5-17-17• Pioneer P008t22R2 • RCB/4 reps• So4 soil test - 6 ppm• OM - 3.1%• Plot size 6x24

Large Plot Trial• Previous crop - Wheat• Seeding date: 5-23-17• Pioneer P008t22R2 - 1.2

units• RCB/4 reps• So4 soil test - 4.3 ppm• OM - 1.5%• Plot size 24x200

Materials & Methods 2018

Small Plot Trial• Previous crop- Ryegrass• Seeding date: 5-31-18• Asgrow AG005x8 • RCB/4 reps• Sulfur soil test - 9 ppm• OM - 4.5 %• Plot size 6x24

Large Plot Trial• Previous crop- Ryegrass• Seeding date: 5-17-18• Asgrow AG005x8 -

1.4units • RCB/4 reps• Sulfur soil test- 10 ppm• OM - 3.4%• Plot size 24x200

Data Collected• Soil samples• Plant emergence and growth• Leaf tissue analysis• RCI (Relative Chlorophyll Index)• Plant height• Soybean yield• Soybean oil content• Soybean protein content

Soybean Yield Influenced by Sulfur Rate and Application Method - 2017

0

5

10

15

20

25

30

35

40

45

50

None 15#S - B 15#S -IF 30#S - B 30#S -IF

Soybean bu/acre

bu/ac

Soybean Yield Influenced by Sulfur Rate and Application Method - 2018

52

53

54

55

56

57

58

59

60

61

None 15#S - B 15#S -IF 30#S - B 30#S -IF

Soybean bu/acre

bu/ac

Large Plot Soybean Yield in 2017 and 2018

Soybean Yield - 2017 Soybean Yield - 2018

05

1015202530354045

bu/A

Soybeanbu/ac

010203040506070

bu/A

Soybeanbu/ac

Summary - Small Plot Trials• In 2017, untreated gave highest soybean

yields and 30#S/ac IF lowest (46.7 vs 38)• In 2018, sulfur applied at 15 and 30#/ac IF gave

4.5 bu/ac more soybean yield than the untreated (55 vs 49.5)

• Plant height, oil % and sulfur tissue tests NS between treatments

• In both years, soybean plant stand was reduced from 30#S/ac applied IF

Summary - Large Plot Trials• In 2017, soybean yield was 8.1 bu/ac higher

from 30#S/ac compared to no sulfur (39.4 vs 31.3)

• In 2018, soybean yields were NS (61.4 vs 61.3) • Plant stand, plant height, %oil and sulfur tissue

tests were all NS• May 2018 was second warmest on record

increased mineralization from soil• In 2017, 4.3 ppm S04, 1.5% OM• In 2018, 10 ppm S04, 3.3 OM

Conclusions• Soybeans respond to sulfur in soils with

low OM and low So4 test• In soils > 3% OM soybean response

mixed. In 2017, at one site all sulfur treatments tended to give lower soybean yields than untreated. In 2018, one site NS, the other higher yield from IF AMS

• IF applications of 30 S #/ac reduced soybean stand in both years

Project Sponsors

Contact Information• Dave Grafstrom

– Northland Community and Technical College– 121 Center Street East, Suite 200– Roseau, MN 56751

• Cell: 320-293-8722

• dave.grafstrom@northlandcollege.edu