Phosphorus Nutrition Of Corn
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Transcript of Phosphorus Nutrition Of Corn
Phosphorus NutritionOf Corn
Outline – P Nutrition of Corn
• Changes in root system development over the season• Impacts on attainable yield potential • Requirements through growth stages • Placement options• Soil test levels and corn response to P inputs• Profitability of P fertility management
36 Days
8 Weeks
MatureSource: Weaver, 1926
Corn Root System Development
The first roots grow from the seed, but the main root system starts from the first node above the seed.
Planting depth affects the depth of the seed roots, but the depth of the initiation of the main root system is the
same, regardless of planting depth.
Fertilizer P2O5
Rate, lb/ARoots colonized at
6-leaf stageCorn dry matter at
silking, tons/A
0 21% 4.5
55 19% 5.0
110 15% 5.2
Mean of 2 years, 1997/98, Quebec. Soil test P (Mehlich 3) was 65 to 87 ppm. Adapted from Liu et al., 2002
Effect of fertilizer P on corn mycorrhizae.
Mycorrhizae
• “Fungus-root”• Extend to absorb P from more soil• Decline with increasing P fertility, fallow
P suppliedShoot P @
V1Shoot P @
V3-V4 Kernel, Yield,
up to V3-V4 % % #/plant bu/A
High 0.58 0.72 444 155
Medium 0.52 0.44 410 138
Low 0.49 0.28 398 134
All treatments received high P after V3-V4 (ISU)Mean of 2 years, 1985-1986
Source: Barry & Miller, 1989
Early P Nutrition – Outdoor Hydroponics
High-yield corn (307 bu/A)Source: Karlen et al., 1988.
How a Corn Plant Takes Up Phosphorus
Source: Mengel & Barber, 1974
Corn grown in silt loam at Purdue Agronomy Farm, Indiana.
Silt loam soil; planted May 5, 1971; final grain yield 187 bu/A.
Nutrient Uptake in Corn Versus Stage of Growth
0
10
20
30
40
50
60
70
80
90
0 15 30 45 60 75 90 105 120 135
Days after planting
To
tal
P2O
5 u
pta
ke,
lb/A
75% Silking
Maximum uptake rate2 lb/A/day @ 45 dap
Maturity
Nutrient Uptake:
• Total uptake ~0.55 lb P2O5
per bushel of grain yield
• Silage harvest removes 3.2 - 4.8 lb P2O5 per ton at 65% moisture
Source: Heckman et al., 2001
0.34 - 0.44 lb of P2O5 per bushel
Nutrient Removal in Grain:
P Deficiency in Corn Seedlings
• Can apply large amounts conveniently• Ideal for building soil fertility• Minimizes risk of fertilizer injury• On fields of low fertility, banded starter P may not be
adequate for maximum yield• Combinations of broadcast and band applications
produce the highest yields on low testing soils
Why Broadcast?
• Overwhelms soil fixation capacity• Places nutrients near the seedling
– Roots intercept early and proliferate near the band– Including ammonium-N, slows P fixation and lowers pH near
the root to improve both P and micronutrient availability
• Favors the crop over the weeds• Keeps nutrients away from the surface
– Reduces runoff P concentrations
Band Application
P P2O5 applied, Grain yield, bu/A
application lb/A 1997-2000 average
Tillage method High P site Low P site High P site Low P site
One-pass None 0 0 168 104
Starter 40 50 171 153
Broadcast 80 100 174 164
Fall band 40 50 164 144
Strip-till None 0 0 164 103
Starter 40 50 169 151
Fall Band 40 50 167 143
Source: Randall, et al., 2001
Placement Options
Source: G.W. Rehm, Minnesota
Low fertility High fertility
Placement Fall chisel Ridge-
till Fall chisel Ridge-till
——— Two-year average, bu/A ———
Control 84 87 156 150
Broadcast 110 102 151 151
Surface band 108 112 152 152
Deep band 118 123 153 153
Fertility Affects Impact of P and K Placement
Source: Bates, 1971; Richards, et al., 1985
• Ontario research from 1960s and 1970s (52 site-years) showed that 6-24-6 @ 50 lb/A with the seed:
– Increased yield by zero to 2.9%– Delayed and sometimes reduced emergence– Hastened time to silking – Decreased grain moisture at harvest
Placing P With the Seed
P2O5 rate, Corn yield,1
lb/A bu/A
0 137
5 151
10 146
21 148
1 Mean of two hybrids at each of two Ontario sites; seed-placed 8-19-3
2 Mean of three Ontario sites3 Mean of three products:
10-34-0, 6-24-6, 8-19-3
Corn yield,2 bu/A
Rate,lb P2O5/A
Liquid3
Granular MAP,
13-52-0
0 145 145
10 156 156
21 152 157
Source: Lauzon et al., 1995
Seed Placement: Small Amounts, Liquidor Granular
Source: Bundy, 2001
Late Planting of Full Season Corn Increased Response to Starter in Wisconsin
Symbol Compound Formula pH
TSP monocalcium Ca(H2PO4)2 1.5phosphate
MAP monoammonium NH4H2PO4 3.5phosphate
TPP1 triammonium (NH4)3HP2O7 6.0pyrophosphate
DAP diammonium (NH4)2HPO4 8.0phosphate
1 Main P form in liquid 10-34-0
P Sources and Solution pH
Soil test Probability of response to Pcategory MN-SD-ND ON Very low > 80%Low 60-80% 75%Medium 40-60% 55%High 20-40% 25%Very high < 20% < 25%
Category definitions vary among laboratories
Soil Test Interpretation: Index of the Likelihood of Crop Response
Source: PKMAN Version 1.0, PPI
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30 35 40
Soil Test P, ppm [Bray P1]
Rel
ativ
e Y
ield
, %
Iowa
Illinois
Missouri
Corn Response to P
Data source: Webb et al., 1992 (Iowa)
Mining P Reduces Soil Test P
298 lb P2O5 in 1975
0 lb P2O5 in 19750
5
10
15
20
25
30
35
40
45
50
1975
1977
1979
1981
1983
1985
1987
1989
Bra
y P
-1 (
pp
m)
Data source: Webb et al., 1992 (Iowa)
Residual Effect of P
298 lb P2O5 in 1975
0 lb P2O5 in 1975
50
75
100
125
150
175
200
1976
1978
1980
1982
1984
1986
1988
Co
rn g
rain
yie
ld,
bu
/A
• Zn deficiency impairs plant P regulation
• Either high soil P or large amounts of applied P can induce Zn deficiency if soil Zn is low and no Zn fertilizer is applied
P2O5 Zn Yield Leaf tissue
lb/A * bu/A P, % Zn, ppm
0 0 101 0.14 12
0 10 102 0.16 24
80 0 73 0.73 10
80 10 162 0.41 17
Data source: Adriano and Murphy
* P and Zn band-applied
Phosphorus and Zinc
• Continuous application of very high rates of P does not always induce greater Zn deficiency (Mallarino, 1995)
Olsen soil test P, ppm
Fertilizer P2O5 applied, lb/A
Corn seedling Zn, ppm
10 18
60 8
115 21
915 18
Adapted from Shang & Bates, 1987
Phosphorus and Zinc
Irrigated continuous corn, Kansas, 30 yearsdata, 1961-1991.
N rate at MEY:with P = 159 lb/Awithout P = 145
P increased N use efficiency instead of greatly increasing N fertilizer demand
Source: Schlegel et al., 1996
Effect of N and P onCorn Yield
60
80
100
120
140
160
180
200
0 20 40 60 80 100 120 140 160 180 200
N rate, lb/A
Yie
ld,
bu
/A
with P
without P
Source: Schlegel et al., 1996, 30 year average
Corn $2.30/bu, N $0.15/lb, P2O5 $0.24/lb; other costs $240/A
The economic optimum N rate with P is 159 lb/A.
P increased profit by about $120/A at this rate
Effect of N and P onNet Revenue
-100
-50
0
50
100
150
200
0 20 40 60 80 100 120 140 160 180 200
N rate, lb/A
Net
rev
enu
e, $
/A
with P
without P
Source: Schlegel et al., 1996; 30 year average
At optimum N rate, P reduced residual nitrate by 66%
P Reduces Residual Soil Nitrate and Potential for Nitrate Leaching After 30 Years
0
50
100
150
200
0 40 80 120 160 200
N rate, lb/A
So
il N
O3-
N i
n u
pp
er
10
ft,
lb
/A
with P
without P
Phosphorus Hastens Corn Maturity
Corn, $2.50/bu; N, $0.15/lb; P2O5, $0.24/lb
Calculated from Dhuyvetter and Schlegel. 1994.
Phosphorus Hastens Maturity and Lowers Drying Costs, Adding to Return to P
0
50
100
150
200
250
0 40 80 120 160 200
Fertilizer nitrogen rate, lb/A
Net
ret
urn
to
40
lb P
2O5/A
, $/
A Drying cost reductionYield response income
Summary -P Nutrition of Corn
• Roots must grow to where the P is, since P is nearly immobile in most soils
• Seedlings provided with high P develop higher attainable yield potential
• Uptake of P continues through the season • Placement near the seedling often boosts yield.• Corn response to P depends on soil test level• P fertility management is key to profitability and
efficient use of N
International Plant Nutrition Institute (IPNI)655 Engineering Drive, Suite 110Norcross, GA 30092-2604Phone: 770-447-0335; Fax: 770-448-0439www.ipni.net
Reference 06128