12/20/2013
IFDC
Using Bio-Organic Acids to
Improve Agronomic Efficiency
of Unreactive Phosphate Rock
Sampson Agyin-Birikorang, Upendra Singh,
Joaquin Sanabria, and George R. Smith
International Fertilizer Development Center
(IFDC)
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12/20/2013
IFDC
Outline

Background and Justification

Hypotheses and Objectives

Testing of Hypotheses

Results and Discussion

Summary and Conclusions
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12/20/2013
P Environmental Footprint from
Phosphoric Acid Method (IFDC – VFRC, 2011)
Sulphuric acid
150 mmt ore
Mining
30 mmt P2O5
Beneficiation
Conversion
30% P not
recovered
~ 20% viable
reserves
65 mmt waste
+ 15 mmt P2O5
~ 320 years life
@ 2010
consumption
75% from phos acid
45 mmt P2O5
Ore content
~ 30% P2O5
Slime ponds
Waste piles
IFDC
4.6x
gypsum/P2O5
~140 mmt gypsum
Incl. ~ 33 mmt S
Stacks
40 mmt P2O5
Application
? % runoffs
? mmt P2O5 in
runoffs
Water systems
Surrounding production facilities
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12/20/2013
IFDC
Problems with the current process?

Efficiency of P recoveries from PR

Environmental concerns: Mountains of
phosphogypsum waste

Economic concerns: Rising costs of
production

Timely availability to small-holder
farmers
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12/20/2013
Direct Application of
Phosphate Rock?
IFDC
Most are non-reactive
Previous studies
• Thermal alteration
• Partial acidulation
• Microbial dissolution
• Amendment with manure and crop residue
• Compaction with WSP at 1:1 ratio
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12/20/2013
Bio-organic acid treatment
IFDC
Rationale

P solubilizing bacteria secrete organic acids to
solubilize metal bound P in soils

Some plant species e.g. Canola exude organic
acids to dissolve PR
Hypotheses
 Some organic acids will solubilize unreactive PRs
to improve their agronomic effectiveness
 Most plants will be able utilize organic acidtreated unreactive PRs
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12/20/2013
IFDC
Objectives
Overall Objective:
Improve the agronomic efficiency of unreactive
PRs for direct application in marginal soils
Specific Objectives:
• Evaluate effectiveness of selected organic acids in
solubilizing PRs for plant use
• Quantify relative agronomic effectiveness of
organic acid-enhanced PRs
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12/20/2013
Preliminary study
IFDC
Greenhouse experiment
Evaluated 4 carboxylic acids: maleic, oxalic, citric, and
gluconic acids
PRs: Idaho PR (unreactive) and North Florida PR (reactive)
Soil: Hiwassee clay loam
Crop: Winter wheat, grown to maturity
P rate: 50 mg P kg-1 soil
Organic acid rate: P/OA molar ratio of 0.99:0.01, ≈ 6 wt% P
All other macro- and micro-nutrients supplied
Measurements: days to heading and maturity, yield, and P
uptake
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12/20/2013
Results of preliminary study
IFDC
Wheat grain yield (g pot -1-1)
Wheat grain yield (g pot )
North
Florida
Idaho
PRPR
100
100
80
80
60
60
40
40
20
20
0
0
TSP
TSP
Check
N-FL PR
Check
Idaho PR
N-FL +
MA +
Idaho
N-FL +
OA +
Idaho
MA
OA
N-FL +
N-FL +
CA + Idaho
GA +
Idaho
CA
GA
Treatments
Initial results indicate that gluconic acid-PRs have RAE ≤ 88%
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12/20/2013
Follow-up studies
IFDC
Gluconic acid
4 PRs: Egyptian, Namphos, Gafsa, and Sachura PRs
3 Crops: Soybean, Wheat, and Canola
Soil: Hiwassee clay loam
All other macro- and micro-nutrients supplied
Measurements: same as previous
Calculation of RAE =
YPR
YTSP
YCTRL
x 100
YCTRL
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12/20/2013
IFDC
Soybean Plants
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12/20/2013
IFDC
Soybean grain yield (g pot-1)
Soybean grain yield
30
No GA
With GA
25
20
15
10
5
0
TSP
Check
Egyptian Sechura Namphos
Gafsa
Treatments
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12/20/2013
IFDC
Relative Agronomic Effectiveness
Treatment
RAE Grain yield
(%)
RAE Biomass yield
(%)
Egyptian PR
17.5
12.8
Egyptian PR + GA
71.9
97.0
Sechura PR
68.7
61.8
Sechura PR + GA
89.6
97.6
Namphos PR
42.7
35.9
Namphos PR + GA
84.8
100
Gafsa PR
59.8
50.5
Gafsa PR + GA
87.1
100
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Wheat Plants
IFDC
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12/20/2013
IFDC
Wheat grain yield
Wheat grain yield (g pot-1)
100
No GA
PR + GA
80
60
40
20
0
TSP
Check
Egyptian Sechura Namphos
Gafsa
Treatments
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12/20/2013
IFDC
Relative Agronomic Effectiveness
Treatment
RAE Grain yield RAE Biomass yield
(%)
(%)
Egyptian PR
1.1
1.3
Egyptian PR + GA
85.8
86.2
Sechura PR
38.2
40.2
Sechura PR + GA
91.5
92.0
Namphos PR
28.1
30.0
Namphos PR + GA
92.1
92.3
Gafsa PR
36.0
40.7
Gafsa PR + GA
92.7
89.1
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12/20/2013
Canola plants
IFDC
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12/20/2013
IFDC
Canola seed yield (g pot-1)
Canola seed yield
No GA
30
With GA
25
20
15
10
5
0
TSP
Check
Egyptian Sechura Namphos
Gafsa
Treatments
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12/20/2013
IFDC
Relative Agronomic Effectiveness
Treatment
RAE Seed yield RAE Biomass yield
(%)
(%)
Egyptian PR
69.5
84.9
Egyptian PR + GA
83.3
98.7
Sechura PR
78.8
92.3
Sechura PR + GA
93.4
100
Namphos PR
76.9
93.6
Namphos PR + GA
91.9
100
Gafsa PR
75.3
97.2
Gafsa PR + GA
92.5
100
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12/20/2013
IFDC
Summary and Conclusions
Amendment of PRs with gluconoc acid was effective:
 improved crop yields with RAE of ~ 85%
 improved P uptake efficiency
We hypothesize that:
 PR bioprocessing with bio-organic acids could
enhance P availability
 This Process will be an energy efficient,
environmentally desirable alternative to current
P fertilizer production technology.
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12/20/2013
IFDC
Thank You
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