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