phosphorus... essential for life
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Phosphorus... Essential for Life. Dr. Mark D. Stauffer President, Potash & Phosphate Institute of Canada Senior Vice President, Potash & Phosphate Institute. Phosphates are a vital ingredient in the diets of all living things…. P. - PowerPoint PPT PresentationTRANSCRIPT
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Dr. Mark D. StaufferDr. Mark D. Stauffer
President, Potash & Phosphate Institute of CanadaPresident, Potash & Phosphate Institute of CanadaSenior Vice President, Potash & Phosphate InstituteSenior Vice President, Potash & Phosphate Institute
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Phosphates are a vital ingredient in the diets of all living things…
• is the second most abundant mineral nutrient in the human body
• 80% of P in humans is in bones & teeth accounting for 20% of the mineral ash & 1% of total body weight
• The remainder is widely distributed throughout the body, in combination with fats, proteins and salts in every cell
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Phosphorus is of universal importance to every living cell…
• Nucleic acids (DNA, RNA, genes, chromosomes)
• Proteins• Lipids• Sugars• Enzymes• Energy rich P compounds
(ATP, ADP)
is incorporated into…
Phosphate chain
ATP: Nature’s energy store
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“Without phosphorus, there is no cell, no plant, and no grain…
Without adequate phosphorus, there is a lot of hunger…”
• Energy storage & transfer for every biological process
•photosynthesis•respiration•cell division, development, enlargement,
gene transfer, reproduction
is critical to basic plant physiology:
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Impact on crops
Vigorous crop (Shoot/Root) growthImproved resource utilization
• water, nutrients• positive environmental implications
Better resistance to stress
• disease, pest, moisture, temperature
Earlier maturity
• good grain & fruit development• better crop quality, yield
LOWERSFARMER
RISK &
RAISES PROFIT
POTENTIAL
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Growing Degree Units
Kg
P /h
a
Grain (Wheat)
Head
Stem
Leaves
30
25
20
15
10
5
0
(Jacobsen et al. 1992)
04/19
3005/10
6006/03
9006/19
12007/13
15007/31
18008/13
is mobile in the plant…linked to metabolic processes…& is concentrated in the most active areas of growth
• the majority of P is removed in fruit/grain
Corn Grain 0.22Stover 0.17
Cotton Seed 0.66Stalks 0.24
Soybeans Grain 0.42Straw 0.18
Wheat Grain 0.42Straw 0.12
Crop Plant part P content, %
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Agronomic characteristics of P deficiency
… purpling of leaves / stems
… darkened leaves
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• reduced leaf number, expansion & surface area
deficiency reflected in poor development at all stages…
• stunted growth
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Impact on plant roots & tillers (wheat)
0 45 90 135 180 225 270 315 360
9
12345678
1011121314
P2O5 Rate, lb/A
Num
ber o
f Adv
entit
ious
Roo
ts a
nd T
iller
s/P
lant
Tillers
Roots
(Fanning and Goos 1992)
80 N
40 N
0 N
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Impact on water use efficiency (wheat)
40 0 26 -1340 45 42 4040 90 49 63
0 0 30 ---0 45 38 270 90 40 33
N P2O5 WUE Increase
kg/ha kg/cm H2O in WUE, %
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Impact on nutrient use efficiency (wheat)
0
100
200
300
400
500
600
0 60 120 180 240
N rate, kg/ha
Wheat K uptake, kg/ha
64kg P
16kg P
0kg P
(Schwartz and Kafkafi)
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(Schlegel, Dhuyvetter, and Havlin, 1996)
Impact on residual soil nitrate & leaching
0
50
100
150
200
0 40 80 120 160 200
N rate, kg/ha
Soi
l NO
3-N
in u
pper
3 m
, kg/
ha
without Pwith P
At optimum N rate P reduced residual nitrate by 66 %
soil profile NO3-N after 30 years…
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Impact on crop maturity (barley)
104106108110112114116118
0 13 27 40
P2O5 Rate, kg/ha
Day
s to
Mat
urity
of B
arle
y
Site 1Site 2
(Westco – Alberta, Canada)
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Impact on yield & cost of production
Schlegel, Dhuyvetter, and Havlin, 1996
40
50
60
70
80
90
100
110
120
130
140
0 22 45 67 90 112 134 157 180 202 224
N rate, kg/ha
Cos
t of p
rodu
ctio
n, $
/t
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
13000
Yiel
d, k
g/ha
with P
without P
30 year average
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OrganicInorganic
Soil Test
How much P is in the soil?
• 4 kg P/ha or less is plant-available in soil solution.
• An actively growing crop can use up all of the P in soil solution twice a day.
• A soil’s ability to maintain a plant-available P supply is the important factor.
Soil Solution
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The Phosphorus Cycle
Plantuptake
Soil solutionphosphorus•HPO4
-2
•H2PO4-1
Primaryminerals(apatite)
Wea
therin
gSecondarycompounds
(CaP, FeP, MnP, AlP)
Dissolution
Precipitation
Mineralsurfaces
(clays, Fe and Al oxides)
Adsorption
Desorption
Organic phosphorus•Microbial•Plant residue•Humus
Mineralization
Immobilization
Crop harvest
Runoff anderosion
Leaching(usually minor)
Loss
Animalmanures
and biosolids Mineralfertilizers
Plant residues
Input
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0
20
40
60
80
100
Low Medium SufficientSoil Test P
PotentialEnvironmental
Problems?
Rel
ativ
e cr
op y
ield
, %
(Sharpley et al. 1993)
Risk of environmental loss?
• Soil tests are good indicators of dissolved P in runoff …… BUT do not indicate environmental risk for a given field
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Phosphorus in the Watershed
Sharpley, Gburek, USDA-ARS; Beegle, Penn State University
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Soil Test P Distribution
Mehlich-3 Pmg/kg<30
30-100>100
Sharpley, Gburek, USDA-ARS; Beegle, Penn State University
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Vulnerability to P LossP loss
vulnerabilityLow (clear)
MediumHigh
Sharpley, Gburek, USDA-ARS; Beegle, Penn State University
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What Determines Phosphorus Fertilizer Need?
Population, Land resources/fertility, Historic nutrient use patterns, Cropping diversity,
Export versus domestic goals, Government policy, Current Economy…
ƒ
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Highly P def soils> 60%
20-40%40-60%
0-20% (Fairhurst et al., 1999)
Indigenous Phosphorus supply - the net effect?
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0.0
0.5
1.0
1.5
2.0
2.5
3.0
1961 1966 1971 1976 1981 1986 1991 1996 2001
US - t/ha
Brazil - t/ha
Soybean yields – US/Brazil
AgriStats, NASS
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0
10
20
30
40
50
60
70
80
1961 1966 1971 1976 1981 1986 1991 1996 2001 2006
Milli
ons Brazil - Area (ha)
Brazil Production (t)US - Area (ha)US - Production (t)
?
Soybean growth – US/Brazil
AgriStats, ANDA, NASS
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0
100
200
300
400
500
600
700
800
900
1,000
1,100
1961 1966 1971 1976 1981 1986 1991 1996 2001 2007
Thou
sand
s US, t
Brazil, t
Soybean P removal – US/Brazil
AgriStats
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EC Joint Research Centre, 2002
Opportunities…• World food demand
• Favorable climate
• Lower land price
• Low production cost
• High yields with fertility correction
• Improving infrastructure
• Political/economical stability
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Smallholder farms - Sustainability of Slash & Burn Systems – Oxisol, Manaus, Brazil
Cravo and Smith, 1997
• 8 years of cultivation after initial slash & burn• 17 consecutive crops
1 2 3 4 5 6 7 8Year After Burning
CROPRiceSoybeanCornCowpea
TREATMENTN & PKLime & CuSB & ZnMnMg
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0
600
1,200
1,800
2,400
1982 1983 1984 1985 1986 1987 1988 1989
Yie
ld, k
g/ha
RiceSoybeanCowpeaCorn
0
20
40
60
80
1984 1985 1986 1987 1988 1989
Yie
ld, k
g/ha
SoybeanCowpeaCorn
No fertilizer:• Total yield = 1.73 t/ha
Cravo and Smith, 1997
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Soil fertility decay pattern – No fertilizer
Cravo and Smith, 1997
Months till 50% Decrease Increase
Org C 134 -Ca 23 -Mg 15 -K 5 -Al - 33pH - 29Zn 21 -
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0
600
1,200
1,800
2,400
3,000
3,600
1982 1983 1984 1985 1986 1987 1988 1989
Yie
ld, k
g/ha
RiceSoybeanCowpeaCorn
NPK plus Lime
Cravo and Smith, 1997
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1 3 5 7 9 11 13 15 170
10
20
30
Yield Response to P
Crop Number
Cum
ulat
ive
yiel
d, t/
ha
Applied Pkg/ha
396
264
132
Control
Cravo and Smith, 1997
• plus 3 t Aglime
**Subsistence farmers require clearing & abandoning 3 new hectares per year to produce the same amount of food on one sustainable hectare
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Gypsum+Lime+PK =3,780 kg/ha
Seed only = 480 kg/ha
Cerrado soil has poor fertility & can’t produce without fertilizers
Dirceu Broch, Fundação MS
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4.86.0
13.5
12.0
4.0 4.0
8.0
5.0
3.55.0
0
2
4
6
8
10
12
14Y
ield
, t/h
a
Rice Corn Beans Soybean Wheat
BrazilCerradoGood farmersExperimentalShort/Med Goal
Compiled from Lopes, 1996 and Yamada, 2003
Grain production gaps
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Soybean P response in Cerrado soil
Source: Fundação MT
0
1,500
3,000
4,500
Yie
ld, k
g/ha
0 80 160 240
033
83114
132
Broadcast & Incorporated, kg P2O5/ha
Seed placed, kg P2O5/ha
3,310
3,220
4,210
640
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TOP FARMER GROUPS: TO DEVELOP AND TRANSFER TECHNOLOGY
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Challenges
• Potential for agricultural expansion is great
• Projections for future production are bold
• Maximum economic yield is always the desired goal
• Adequate P is a crucial part of the yield equation responsible for reaching this goal
• How sustainable is this production?
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0
20
40
60
80
100
120
140
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000
USAChinaIndiaFranceArgentinaBrazil
P consumption – world comparisons (kg per arable ha)
AgriStats
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0
10
20
30
40
50
60
70
80
1961 1966 1971 1976 1981 1986 1991 1996 2001
Milli
ons Brazil - Area (ha)
Brazil Production (t)US - Area (ha)US - Production (t)
Soybean growth – US/Brazil
AgriStats, ANDA, NASS
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pH &high soil P
Irrigation
Variety Seeddensity Early
Seeding &high soil K
Low compaction
Early seeding
Crop rotation
High soil P0102030405060708090
% In
crea
se
YieldN use efficiency
Best management practices
(Corn results from several U.S. state’s)
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$/ha0 100 200 300 400 500 600
Rel
ativ
eel
evat
ion
(m)
405
402
360
300
240
180
120
60
South to north
distance (m
)
060
120 180 240
West to east distance (m
)
Within-field returns fromoptimum N/P rates (Corn)
12 hectares, 1997Southwestern MNMalzer et al, U of MN