Phosphorus: World Wide Supplies and Efficiency

Phosphorus: World Wide
Supplies and Efficiency
Paul Fixen
Sr. Vice President
[email protected]
2009 Manitoba Agronomists Conference
Winnipeg, Manitoba
December 16, 2009
http://www.potashcorp.com/customer_service/market_research/market_statistics/market_report/
DAP
Source: Heffer (IFA, Nov. 2009)
Sept. 2009
Aug. 2009
Nature, Oct. 2009
June 2009
2008
Hubbert curve: production reaches a maximum when 50% of the resource
is depleted and declines thereafter.
Peak phosphorus … like peak oil??
2030
White and Cordell, 2009.
Economic and potentially economic phosphate
deposits of the world
Sedimentary deposits comprise 80% of RP
production
McClellan and Van Kauwenbergh, 2004.
World phosphate rock production, 1981-2008
Rather flat at 120 to 165 MT per yr
Others
Former
Soviet Union
Brazil
Jordan
Tunisia
China
Morocco
United States
11992-1997
2Year
FSU includes Kazakhstan and Russia data; afterwards, Russia only.
2008 estimated. Compiled from USGC Mineral Commodities Reports, 1983-2009.
About reserve and reserve base estimates
• Definitions:
– Reserves can be economically mined at the time of determination
– Reserve base includes economic and some currently uneconomic resources
• Estimates are plagued with uncertainty
– Producers consider reserve information to be confidential
– Published scientific papers and specific deposit reports are primary information sources
– Should be viewed as general approximations
World phosphate reserves* in 2008
Senegal Togo
Total = 15 billion
Tunisia
Brazil Canada
metric tons
1%
2%
Others
Egypt
6%
1%
Syria
Israel
Jordan
1%
1%
6%
Russia
Morocco & W. 1%
S. Africa
Sahara
10%
Australia
37%
1%
U.S. 8%
* Reserves can be
economically mined at the
time of determination.
Data Source: USGS, 2009.
China
27%
World phosphate reserve base* in 2008
Tunisia
Egypt 1%
Brazil
1%
Canada
Others
5%
2%
Syria
Israel 2%
2%
Russia
2%
Australia
3%
Total = 47 billion
metric tons
Jordan
4%
S. Africa 5%
U.S. 7%
* Reserve base includes
economic and some currently
uneconomic resources.
Data Source: USGS, 2009.
Senegal
Togo
China
21%
Morocco & W. Sahara
45%
Phosphate mine reserve life and reserve base life
World
291
93
Data Source: USGS, 2009 (based on 2007‐2008 production).
Phosphate reserve and reserve base estimates
• Great uncertainty exists in estimates. Examples:
– USGS RP world estimates (billion metric tons):
• In 2002 Reserves = 13; Reserve base = 47
• In 2009 Reserves = 15; Reserve base = 47
• After 7 yrs, 2009 estimates were 122% and 100% of 2002 estimates. – Sheldon world estimates (billion metric tons):
• In 1987 Reserves = 15; same as 2009 USGS estimates
• Resources (reserve base + inferred base) = 112 … a longevity of nearly 700 yrs based on today’s production. • Clearly, the world is not on the verge of running out of phosphate raw materials.
• Just as clearly, RP is a non‐renewable natural resource of immense importance to food production and deserves are very best stewardship. Nutrient Use efficiency terminology
Example:
P applied (F)
Grain yield (Y)
P Uptake (U)
P removal (UH)
lb/A (P2O5)
bu/A
lb P/A
lb P/A
20 (45)
Y = 60
U = 20
16
0
Y0 = 50
U0 = 17
NUE Term
Calculation Example
Agronomic efficiency
(Y-Y0)/F
(60 bu/A - 50 bu/A) x 60 lb/bu = 600 lb grain
600 lb grain/20 lb applied P = 30 lb grain/lb P
Recovery efficiency
by difference
(U-U0)/F
(20 lb P/A -17 lb P/A) / 20 lb P applied = 15%
Recovery efficiency
by balance*
UH/F
16 lb P/A / 20 lb P applied = 80%
* Also referred to as “partial nutrient balance” or “removal to use ratio”.
Influence of soil fertility on efficiency of P
fertilizer use in wheat experiments in Argentina
28% 1st yr
recovery
by difference
Near 0%
recovery
by difference
Garcia, 2004.
Recovery efficiency by
balance method for P
Better Crops
2009 (3)
• Global review by Syers, Johnston and Curtin (2008).
• When soils are maintained near the critical level for crop yield, P recovery efficiency by the balance method frequently exceeds 90%.
Example of critical soil test level
(as defined by Syers et al.)
Critical level
Availability and extractability of soil P pools
Extractability
by soil tests
Johnston and Syers, 2009.
As P is applied to soils only a portion ends up
in soil test extractable forms
Line representing 13%
of added P remaining as
Olsen P
Other studies in North
America show up to
20-25% remaining soil
test extractable
Johnston and Syers, 2009.
Availability and extractability of soil P pools
< 25% of applied P
> 75% of applied P
Extractability
by soil tests
Johnston and Syers, 2009.
For most soils, much of this 75%+
enters the low availability pool …
becomes plant available over time
P Efficiency for Prairie Province Soils
• Read et al (1973): Single applications of P to 4 Chernozems in MB and SK; 100, 200, and 400 kg P/ha
– 3 yrs after applying P, surface soil collected and cropped in greenhouse to oats and barley, 19 crops
– Avg recovery was 87%, 81% and 70% respectively
• Sadler and Stewart (1974): “There is sufficient evidence to show conclusively that a considerable portion of fertilizer P (approximately 75%) not used by the first crop immediately following application, remains in chemical form which is available to succeeding crops, provided that the rooting distribution of the ensuing crop and critical growth factors permit it to be utilized.”
• Doyle and Cowell (1993): “Most applied P will eventually be recovered by crops on the Canadian prairies.”
Syers, Johnston and Curtin, 2008 (p 67).
Another consideration when P recovery is
assessed by difference
• When crops do not receive P, they may be more efficient at acquiring soil P than those that do receive P
• Causes:
– More effective mycorrhizal associations
– Great allocations of CHO from photosynthesis to grain when P is limiting
– Uptake of P deeper in the soil profile when P in the surface is limited
– Ability of the plant to change conditions in the rhizosphere in response to low levels of available soil P
Syers, Johnston and Curtin, 2008 (p 68).
Recovery efficiency by balance method in MT,
ND, and SD (NuGIS, IPNI).
Median Bray P, ppm
P removal/use* ratio
State
2001
2005
2002
2007
Average
MT
12
14
0.91
1.04
0.98
ND
10
11
1.07
1.01
1.04
SD
11
14
1.06
1.00
1.03
* Use = Fertilizer P applied plus recoverable manure P.
Replacing the P removed in the harvested portions of crops
appears to be maintaining soil P as indicated by soil tests =
Recovery efficiency by balance is near 100%.
P-2007
U.S. 48
0.92
1.1
1.2
1.2
1.3
1.6 1.2
0.9
1.0
Inputs and outputs of N & P by managed pathways.
Nutrient balances by region (kg/ha/yr)
Western Kenya North China Midwest U.S. (low input (wheat/corn
(corn/soy‐
corn‐based)
double crop)
bean)
Inputs and outputs N
P
N
P
N
P
Fertilizer
7
8
588
92
93
14
Biological N fixation
62
Total agronomic inputs
7
8
588
92
155
14
Removal in grain and/or beans
23
4
361
39
145
23
Removal in other harvested products
36
3
Total agronomic outputs
59
7
361
39
145
23
Agronomic inputs minus harvest removals
‐52
+1
+227
+53
+10
‐9
Removal to use ratio (partial nutrient balance or recovery by balance method)
Vitousek et al. (Science, 2009).
0.88
0.42
IL Median Bray P
in 2005 = 36 ppm
1.64
Summary
• World P reserves and resources appear adequate for the foreseeable future;
– Nutrient costs will rise over time as
the most easily extracted materials are consumed.
• An added incentive for continued refinement and implementation of fertilizer BMPs:
– The resulting gain in efficiency will slow the increase in costs.
• Wise stewardship of non‐renewable nutrient resources is a critical responsibility for the agriculture industry.
• Global evidence indicates that maintenance of soil test P near the critical level results in P efficiency by the balance method frequently exceeding 90%.