Download 5 lb P 2 O 5 - International Plant Nutrition Institute

Phosphorus Nutrition of
Soybean
Outline –
P Nutrition of Soybean
•
•
•
•
P uptake by above-ground plant tissue
Soybean root morphology
P influx by roots
Yields and soil test P levels
• P placement
• P timing
• P and soybean pests/diseases
P Uptake by AboveGround Plant Tissue
Examining uptake throughout
the season
Aerial accumulation (lb/acre)
Nutrient Uptake by 80 bu/A Soybeans
450
400
N
K2O
P2O5
350
300
250
200
150
100
50
0
0
20
40
60
80
100
Days after planting
Source: Henderson and Kamprath, 1970
120
140
160
Soybean P Uptake
100
90
% of total uptake
80
Total P uptake:
12 – 24 lb P2O5/A
70
Beans
60
50
Pods
40
Stems
Petioles
30
20
Petioles (fallen)
Leaves
Leaves
(fallen)
10
0
0
28
V1
Source: Hanway and Weber, 1971
56
V6 V10
84
R4
112
R6 R7
Days after emergence
Growth stage (inferred)
Soybean Phosphorus Derived
from Fertilizer
Soybean plant fraction
P derived from fertilizer
(%)
Leaves (and petioles?)
36
Stems
20
Pods
25
Beans
16
Source: Ham and Caldwell, 1978
Soybean Phosphorus Content Derived
from Fertilizer
% of P derived from fertilizer
Soil P level
60
Low
50
40
Medium
30
High
20
10
0
20
40
60
80
Days after planting
Source: Bureau et al., 1953
100
120
Soybean Root
Morphology
Establishing a background for
discussions of P placement
Soybean Root Growth
6 in.
• Phase 1
(1st month after planting)
– Rapid vegetative top growth
– Downward taproot growth
– Development of horizontal
laterals in upper soil profile
Source: Mitchell and Russell, 1971
Soybean Root Growth
• Phase 2
(2 – 2.5 months after
planting)
– High rates of top growth
(from flowering through
pod formation)
– More laterals develop in
upper soil profile
– Some laterals begin to
turn downward
6 in.
Source: Mitchell and Russell, 1971; Raper and Barber, 1970
Soybean Root Morphology
• Left side:
single soybean plant
grown in isolated plot
– Primary lateral
roots branch from
taproot within upper
15 cm (6 in.)
– Below 15 cm
(depth of
cultivation), taproot
degenerated to a
root with a diameter
similar to primary
laterals but with
less branching
Source: Raper and Barber, 1970
(approx. 10 wk. after planting)
Soybean Root Morphology
• Right side:
soybean grown in 30
in. rows
– Primary lateral
roots branch from
taproot within upper
15 cm (6 in.)
– Near center of rows
(45 cm or 18 in.),
laterals angle down
sharply as they
encounter root
zone of neighboring
plant
(approx. 10 wk. after planting)
Source: Raper and Barber, 1970
Soybean Root Growth
• Phase 3
(Seed set to maturity)
– Continued rapid rates
of downward
extension of laterals
– Laterals penetrated
deeper than the tap
root
Source: Mitchell and Russell, 1971
Depth of
sample
(in.)
Root dry weight at the following
days after planting:
31
67
80
102
-------------- (grams) -------------
0 - 3
0.24
2.60
3.10
4.23
3 - 6
0.04
0.26
0.73
0.52
6 - 9
0.01
0.07
0.12
0.08
9 - 12
0.01
0.04
0.07
0.04
12 - 18
--
0.05
0.10
0.04
18 - 24
--
0.03
0.10
0.08
24 - 36
--
0.07
0.08
0.07
36 - 48
--
--
0.06
0.06
48 - 72
--
--
--
0.03
Portion of total root length
in P-treated volume
Roots Proliferate in Zones of Higher P
Concentration
0.8
Soybean
0.7
Corn
0.6
1:1
0.5
0.4
0.3
0.2
0.1
0
0
Source: Borkert and Barber, 1985
0.1
0.2
0.3
0.4
0.5
P treated soil portion, %
0.6
Effects of P or Mycorrhizae
on Soybean Shoot Dry Weight
3.0
Non- mycorrhizal DM
Non-mycorrhizal infection
Mycorrhizal DM
Mycorrhizal infection
2.5
100
80
2.0
60
1.5
40
1.0
20
0.5
0
Initial Bray 1 soil test P = 8 ppm
0
115
345
Applied P rate, lb P2O5/A
Source: Lambert et al. 1979
920
0
% of root colonized
Shoot dry weight, grams
Greenhouse study
Management Factors Affecting Soybean
Root Morphology
• Cultivar choice
– Root angle
– Root elongation rate
• Planting date
– Soil temperature
– Soil moisture
– Photoperiod
– Quantity of radiation
Source: Coale and Grove, 1986
• Tillage
– Soil moisture
– Soil temperature
– Soil bulk density
– Soil aeration
• Soil fertility
– Plant dry matter
distribution
– Root proliferation
• Irrigation
– Soil moisture profile
P Influx by Roots
Examining how quickly roots
can absorb P
Nutrient Influx by Roots
– H2PO4-, HPO42– K+
• Maximum influx is
reached at higher
solution concentrations
(Imax)
Sources: Barber, 1984; Edwards and Barber, 1976
22-23 day old soybean roots
Influx, 10-14 lb P2O5 / (in2 s)
• Ions are not simply
absorbed according to
their ratios in solution
• Ions with this
characteristic influx
pattern require energy to
be absorbed
3.0
Imax
2.5
2.0
1.5
1.0
0.5
0.0
-0.5
0
1
2
3
4
Solution P, 10-6 lb P2O5/gal
5
Nutrient Influx Depends on Both P and
K Fertility
Low P limits P diffusion
and energy for P uptake
Low P limits energy
for K uptake
Influx, 10-13 lb / (in2 s)
P2O5 influx by soybean roots
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
K2O influx by soybean roots
55 ppm Bray P-1
55 ppm Bray P-1
11 ppm Bray P-1
50
70
90
110
11 ppm Bray P-1
130
150 50
70
Soil test K, ppm
Source: Hallmark and Barber, 1984
90
110
130
150
Influx, 10-5 lb P2O5 / (in. day)
P Influx Varies with
Plant Age
5
Corn
4
3
2
1
Soybean
0
0
-1
Sources: Barber, 1978; Mengel and Barber, 1974
20
40
60
80
Plant age, days
100
120
Yields and Soil Test P
Levels
Examining how production
level is related to soil test
P level
Relative grain yield, %
Soil Test P Calibration Data
100
80
60
40
Corn
20
Soybean
0
0
10 20 30 40 50 60 70 80 0
10 20 30 40 50 60 70 80
Soil test Bray P-1, ppm
Source: Mallarino, 1999
Comparisons of Soil Test P Calibration
Data
120
Relative yield, %
100
80
60
40
20
MO
IL
AR
KY
MS
AL
0
0
5
10 15 20 25 30 35 40 0
5
10 15 20 25 30 35 40
Bray P-1 soil test level, ppm
Source: Snyder, 2000
P placement
Broadcast and banded
applications
Nutrient Placement Considerations
Source: Anghinoni and Barber, 1980
Conceptual model
(nutrient deficient soil)
Dry matter yield
• Banding:
– Less soil volume
fertilized
– Smaller portion of
fertilizer is “tied up”
– Roots proliferate
where N and P are
found
– Rate may be too low to
maximize yield
• Fewer roots
exposed to supply
• Increase in influx
rate by roots may
not compensate
for fewer total
number of roots
near P supplies
High nutrient rate
Low nutrient rate
0
20
40
60
80
100
Fertilized soil fraction, %
Starter vs. Broadcast:
Irrigated Zone
• Band placement:
2 in. below
2 In. to the side (2x2)
Source: Rehm, 1986
Range in average yields:
50 - 71 bu/A
25
Soybean yield response, %
• 3 of 10
site-years responded
significantly
• pH:
7.6 – 8.1
• Olsen P:
5.6 – 10.7 ppm
• Calcareous soil
20
Broadcast
15
2x2 Band
10
5
0
0
-5
20
40
60
P2O5 rate, lb/A
80
100
Starter vs. Broadcast:
Dryland Zone
Yield response, %
60
50
1 in. below
40
1 in. x 1 in.
30
With seed
20
Spring broadcast
10
Fall broadcast
0
-10
0
25
50
75
P rate, lb P2O5/A
Source: Bullen et al., 1983
100
125
Starter vs. broadcast:
Temperate Rain Fed Zone
• 20 site-years at
research stations
Source: Borges and Mallarino, 2000
13.1
11.6
3.9
Starter
3.9
Broadcast
Averaged over
all sites
Starter
14
12
10
8
6
4
2
0
Broadcast
• 9 sites tested Very Low
to Low
(6 to 15 ppm Bray P-1)
• 7 of the 9 sites (78%)
(6 to 11 ppm Bray P-1)
showed significant
responses to P
• P placement did not
influence soybean yield
Yield response, %
• 4 – 29 ppm
Bray P-1
Averaged over
responsive sites
19.6
Bray P-1: 3.5 ppm
NH4OAc K: 150 ppm
14.0
band
broadcast
broadcast + w/seed
15
w/seed
Yield response, %
20
19.9
broadcast + band
Comparison of Placement Combinations
and Rates
4
10
0
4
10
P2O5: 18
46
60
78
106
K2O:
12
30
35
42
10
7.2
5.0
5
0
N:
Source: Ham et al., 1973
5
Deep Banding vs. Broadcast
• 20 site-years at research
stations
• No-till systems
• 0 – 6 in. soil samples:
Range in average yields:
26 – 63 bu/A
30 in.
– 4 – 29 ppm Bray P1
– pH 5.9 – 7.1
• Significant responses to P
occurred on 7 sites ranging
from 6 – 11 ppm Bray P1
– Average response at these
sites:
4.6 bu/A
– 5 of the 7 sites showed no
differences in placement
Source: Borges and Mallarino, 2000
6 - 8 in.
30 in.
Deep Banding vs. Broadcast
• 11 site-years on farmer
fields
• No-till systems
• 0 – 6 in. soil samples:
Range in average yields:
37 – 58 bu/A
7.5 in.
– 5 – 34 ppm Bray P1
– pH 5.8 – 7.5
• Across all site-years, there
was a slight
(1 bu/A) advantage to P
fertilization, and no
difference between
placement methods
Source: Borges and Mallarino, 2000
6 - 8 in.
30 in.
Considerations for
Placement
• Banding is expected to be superior when soil test levels
are low and only smaller rates of P are applied
• Broadcast applications may be superior to banded
applications when rainfall or irrigation keeps moisture in
the upper part of the soil profile
• Placement of bands directly below the seed may be
better than other band placements
• Band and broadcast applications used together may be
better than either one applied on its own
P Timing
Comparing fresh and
residual effects of fertilization
Annual vs. Biennial:
Broadcast Applications
• Corn/soybean rotation
• Long no-till history
• P timing (0-46-0)
– Every 2-yr.
80 lb P2O5/A
– Every yr.
40 lb P2O5/A
• 2 of 4 site-years showed
no timing differences
• 1 site (18 ppm Bray P1):
annual > biennial by 3 bu/A
• 1 site (37 ppm Bray P1):
biennial > annual by 3 bu/A
Source: Buah et al., 2000
Range in average yields:
24 – 48 bu/A
30 in.
Annual vs. Biennial:
Broadcast Applications
• Corn/soybean rotation
• Long no-till history
• P timing
– Every 2 yr.
(0, 30, 80, 160 lb P2O5/A)
– Every yr.
(0, 15, 40, 80 lb P2O5/A)
– Direct > residual 2 out of 3 years
– 2 bu/A average response
– Bray P-1: 6 – 14 ppm
Source: Buah et al., 2000
Range in average yields:
37 – 46 bu/A
10 in.
Annual vs. Biennial:
Starter Applications
• Corn/soybean rotation
• Long no-till history
• P timing (0-46-0)
Range in average yields:
24 – 48 bu/A
– Every 2-yr.
80 lb P2O5/A
– Every yr.
40 lb P2O5/A
• 2 of 4 site-years showed
no timing differences
• 1 site (18 ppm Bray P1):
annual > biennial
by 6 %
• 1 site (37 ppm Bray P1):
biennial > annual by
13 %
Source: Buah et al., 2000
30 in.
3 - 4 in.
2 in.
30 in.
Annual vs. Biennial:
Starter Applications
• Corn/soybean rotation
• Long no-till history
• P timing
– Every 2 yr.
(0, 30, 80, 160 lb P2O5/A)
– Every yr.
(0, 15, 40, 80 lb P2O5/A)
– Annual > biennial 2 out of 3
years
– 2 bu/A average response
– Bray P-1: 6 – 14 ppm
Source: Buah et al., 2000
Range in average yields:
37 – 46 bu/A
10 in.
4 in.
30 in.
% of yield attained with
600 lb P2O5/A applied initially,
and 67.5 lb P2O5/A applied annually
Residual effect of a single, large
application of P
0 lb P2O5 applied initially
67.5 lb P2O5/A applied annually
120
110
100
90
80
70
600 lb P2O5 applied initially
0 lb P2O5/A applied annually
60
50
40
1975
1980
1985
1990
Year
Source: Dodd and Mallarino, 2005
1995
2000
Timing Considerations
• Cases where annual applications may be better than
biennial applications in no-till systems:
– Soils with lower soil test levels
– Soybeans planted in narrower rows
• Other tillage systems need to be investigated
• Single, larger applications of P can have significant
residual value
– Builds soil test levels
– Can be performed when economics of larger applications are
favorable
– Allows P to be omitted in times of unfavorable economic
conditions
Phosphorus and soybean
pests/diseases
Nutrition and Foliar Diseases:
Asian Rust
Rate
N
P2O5
Upper extent
Lesion
Type of
Overall
K2O
of rust lesions
density
pustule
rating
(lb/A)
80
0
0
upper third
heavy
sporulating
susceptible
0
61
0
upper third
medium
sporulating
mod. susceptible
0
0
32
upper third
medium
sporulating
mod. susceptible
80
184
0
upper third
heavy
sporulating
susceptible
27
61
32
middle third
medium
non-sporulating
mod. resistant
Source: Piccio and Fanje, 1980
SMV incidence, %
Nutrition and Diseases:
Soybean mosaic virus
50
45
40
35
30
25
20
15
10
5
0
K2O
P2O5
N
Total N + P2O5 + K2O,
at equal rates
0
25
50
75
100
Nutrient rate, lb/A
Source: Pacumbaba et al., 1997
125
150
Nutrition and Nematodes:
Soybean cyst nematode (SCN)
18
16
14
12
10
8
6
4
2
0
30
25
Yield response
20
15
10
5
0
0-0
30-30
60-60
90-90 120-120
Fertilizer mixture (P2O5 - K2O), lb/A
C/C
Source: Howard et al., 1998
S/S
C/S
Yield response
Yield response, %
Cysts / 100cc
Cultivar highly susceptible
to SCN races 3 and 4
Nutrition and Nematodes:
Soybean cyst nematode (SCN)
18
16
14
12
10
8
6
4
2
0
30
25
20
Yield response
15
10
5
0
0-0
30-30
60-60
90-90 120-120
Fertilizer mixture (P2O5 - K2O), lb/A
C/C
Source: Howard et al., 1998
S/S
C/S
Yield response
Yield response, %
Cysts / 100cc
Cultivar resistant
to SCN races 3 and 4
Conclusions
• At harvest, most of the P in the above-ground portion of soybean is
in the grain
• At lower soil test levels, more of the P taken up by the plant comes
from applied P
• In the first month after planting, root development is primarily
characterized by elongation of the taproot
• In subsequent months, soybean develops much of its root system
near the soil surface
• Compared to corn, the rate of P influx by soybean roots is about 4
times slower in the first 20 days
• P proliferates soybean roots when present in concentrated zones
• Mycorrhizae can increase soybean growth at low soil test P levels,
even when P is applied
Conclusions
• Soil test calibration data provide a biological evaluation
of chemical tests
• Average calibration relationships can be similar across
large geographies
• Placement of bands directly below the seed may be
better than other band placements
• Band and broadcast applications used together may be
better than either one applied on its own
• Annual applications appear to be superior to biennial
applications when plant spacing is narrower and soil
tests are low
• P can help reduce the incidence and or severity of
some soybean diseases
International Plant Nutrition Institute (IPNI)
655 Engineering Drive, Suite 110
Norcross, GA 30092-2604
Phone: 770-447-0335; Fax: 770-448-0439
www.ipni.net