Soybean Nutrient Management - A Risk Management Tool

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Soybean Nutrient Management
A
“Risk Management Tool”
by
Dale Cowan
Agri-Food Laboratories
Guelph
AGRI-FOOD LABORATORIES

Soybean Nutrient Management
Growth Stages
Nutrient Requirements
Tools to Determining Nutrient Requirements
Factors affecting Nutrient Uptake
Role of Nutrients in Plant Health
AGRI-FOOD LABORATORIES

Growth Stages
There are definite
VE emergence
growth stages that a
VC cotyledon
soybean plant
V1 first node
progresses through from Vn depends on variety maturity
emergence to
R1 beginning flowering
maturation.
R2 full bloom
R3 podding
R4 full pod
R5 seed filling
R6 full seed
R7 beginning maturity
AGRI-FOOD LABORATORIES
R8 full maturity

Growth Stages
The rate of development is related to temperature.
The length of time between stages varies directly with the
weather.
Nutrient deficiencies, lack of moisture, increases the length of
time between the vegetative stages but decreases the time
between reproductive stages.
Plant densities affect the physical appearance of plants, high
densities >225,000 plants causes tall, sparsely branched
growth habit, fewer pods and seeds per pods, prone to lodging.
R5 is a critical stage.
AGRI-FOOD LABORATORIES

Growth Stage R5
This growth stage is the beginning of seed filling
stage and denotes a major change in the flow of
nutrients.
Essentially maximum root expansion and nutrient
uptake has occurred.
The nutrients are translocated to the seeds.
Maximum uptake of K is important for yield at this
stage.
Plants that have an inadequate supply of K at this
stage will not be able to maximize yield.
AGRI-FOOD LABORATORIES


Nutrient Requirement of Soybeans
Nutrient requirements to produce a 50 bushel Crop of soybeans
Nutrient
Reproductive
Vegetative
Total lbs per acre
Growth
Growth
Nitrogen
185
100
285
Phosphorous
42
28
70
Potassium
72
65
137
Magnesium
32
Calcium
75
Sulphur
25
Zinc
0.20
Iron
1.70
Manganese
0.60
Copper
0.10
Boron
0.10
Molybdenum
0.01

Estimated Crop Removal in a Rotation lbs / acre
Crop
Yield
N
P2O5
K2O
Mg
Ca
Level
Soybean
50 bu
200
42
70
9
11
Corn
150 bu
149
55
45
13
1
Winter
75 bu
90
45
28
12
2
Wheat
Total
------
439
145
143
34
21
AGRI-FOOD LABORATORIES

Average P by County % Distribution by Range
County
Avg P
7-9
9-15
15-20
25-30
30-40
ppm
Brant
55
-
7
15
12
6
Elgin
29
4
14
18
11
11
Essex
32
3
19
18
14
10
Hald-Norfolk
59
1
7
9
6
5
Huron
29
3
18
16
13
11
Kent
31
3
15
16
14
11
Lambton
28
3
18
15
13
12
Middlesex
29
3
19
18
14
12
Oxford
52
2
10
9
8
8
Perth
48
1
10
9
9
8
Waterloo
41
2
10
11
11
9
Simcoe
27
7
18
13
9
7
Wellington
31
5
21
14
11
9

Average P by County % Distribution by Range
County
Avg P
7-9
9-15
15-20
25-30
30-40
ppm
Carleton
23
8
27
14
14
9
Stormont
19
9
28
18
13
6
Dundas
Leeds Grenville
30
9
17
9
14
8
Prescott Russell
28
4
4
16
15
165

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