Ben ChaffinChaffin FarmsIthaca, Michigan
Crops• Sugar beets
• Corn
• Corn silage
- Soybeans
• Edible beans
- Blacks
- Navy
• Potatoes
- ground rented out
• Hay
• Peas
• Wheat
• Rye
• Organic Crops
- Peas
- String beans
- Corn
- Squash
Soil TestingFrequency• 3 Years manure
- Michigan regulation
• 4 Years no manure
- Industry standard
• Grid samples
- 10 acre grids $4.50 / acre
- 2.5 acre grids $8.50 / acre
Commercial Nutrient Management
Nutrient focus• Nitrogen
• Phosphorous
• Potassium
• Lime
• Micro nutrients
Variable rate applications• Changing amount applied while spreading a field based on
- Soil tests
- Yield goals
- Crop needs
Fertilizer Spreader Variable rate spreading Fall 2010 Spreader costs $110K 3 years old, new $225KGPS technology $15K
Animal Nutrients
• Manure management
- All nutrients mixed together
- Cost to haul
• Manures used
- Dairy 3,000 acres
* 3-5 miles or less transportation negotiated
* We incorporate same day applied
- Turkey & Chicken 1,500 acres
* 100 miles $50/ton delivered spread
- Swine 50 acres
* 5-10 miles all hauling costs
• Limited amount of manure
Irrigating ManureIrrigating ManureN 1.1 lbs / 1000 galP .9 lbs / 1000 galK 1.4 lbs / 1000 galN,P&K very lowIrrigated 2.4M gal in 2010
Manure lagoon
Pump to irrigation system
Fixed investment to irrigate 35 acres $70K
Commercial Phosphorous• Dry
- MAP 10-52-0 $0.52/lbs phos.
- DAP 18-46-0
* Dry mixes cheaper per lbs phosphorous
• Liquid
- 10-34-0 $0.64/lbs phos.
- 8-25-3
* More money per lbs phos phorous
Decision Points• Cost benefit
• Return on investment
- 10% on new products example fungicide on corn
• Time / effort
- Split applications verse 1 application
• Operational fit
• Risk management
Planting Corn Spring 2010 Seed and fertilizer applied with variable rate technology Rates based on yield goals for each segment of the field
Corn Harvest 2010 Combine mapping yields for future use
Ever Had One of These Days?Sugar Beet Harvest Fall 2010
GLOBAL PHOSPHORUS SCARCITY:CHALLENGES & OPPORTUNITIES FOR FOOD SECURITY
Dr Dana Cordell
Sustainable Phosphorus Summit, Tempe Arizona3rd February, 2011
THINK.CHANGE.DO
INSTITUTE FOR SUSTAINABLE FUTURES
• Joint initiative co-founded in 2008 (Linköping University & University of Technology, Sydney)
• Today -5 research organisations across Australia, Europe and North America
• Aim:
- to facilitate quality interdisciplinary research on global phosphorus security for future food production.
- networking, dialogue and awareness raising among policy makers, industry, scientists and the community on the implications of global phosphorus scarcity and possible solutions.http://phosphorusfutures.net/
Dependence On Phosphate Rock
Global Phosphorus Research Init iative
Phosphate rock commodity price
Background: The Current Situation2008price spike: US$50/tonne to US$430/tonne
Food riotsOil prices soarFertilizer (N, P, K) prices soarsFood prices soarFertilizer riots
• Vigorous debate today –will we run out of phosphorus? Peak phosphorus?
• 30 yrs –300 years
• IFDC report:
- 60 billion tonnes of phosphate rock (USGS 16 billion)
- No peak phosphorus 25 years, or this century
- 300-400 years left, at current production rates
- GPRI: Figures are unreliable and do not change underlying problems, nor the threat of peak P this century
Scarcity: More Than Just PhysicalPhysical Scarcity: Peak Phosphorus• Like oil, phosphate rock will eventually reach a production peak due to energy and economic constraints -estimated peak P by 2035
• No alternative sources of P on market today could replace demand for P rock: significant institutional and physical infrastructure will be required
• Timing of peak uncertain, but widely recognised:
tonnes ‘in the ground ’is not the same as tonnes ‘on the field’
accessible to farmers
Cordell & White, 2011
- qualityis declining
- (less P2O5, more impurities)
- access is more difficult
- energy increasing
- costsincreasing
- wastes increasing
- (e.g. phosphogypsum)
Peak phosphous curve
Managerial Scarcity: Inefficient Phosphorus Use In The Global Food System
Cordell et al, 2009
Cordell et al, 2009
Institutional Scarcity: Whose Responsibility?• Scarcity resulting from a lack of appropriate and effective institutional structures to ensure P supply will meet long-term demand.
- eg. there are currently no explicit international or national policies, regimes, guidelines or organisations responsible for ensuring long- term availability and accessibility of phosphorus for food production
• Market system governing by default –alone not sufficient to ensure equi table, timely, sustainable
• Whose responsibility is long-term phosphorus security? Governance of phosphorus is fragmented between many different sectors
Geopolitical Scarcity: Remaining ReservesAll farmers need phosphorus, yet just 5 countries control around 85%of the worlds remaining phosphate rock reserves
World phospate rock reserves by countryData: Jasinski, S (2010) Phospate Rock, Mineral commodity Summaries, US Geological Survey
Economic Scarcity: Lack Of Access To Phosphorus• Farmers need both short-and long-term access to fertilizers
• Lack of access to phosphorus fertilizers-eg. lack of farmer purchasing power, access to credit
• Phosphorus inequity: African continent
- largest high quality phosphate rock
- Low soil fertility
- Poorest farmers
- lowest P fertilizer application rates
- High food insecurity
- significant ‘silent’ demand from farmers with low purchasing powerin sub-Saharan Africa
Challenges: Achieving Phosphorus Security• Integrated approach is required: there is no single solution to meeting future phosphorus demand
• Multi-scale response: strategies need to respond to global issues but designed to be context specific
• Beyond the market focus
• Beyond ‘the field’ focus (eg. more than ag efficiency)
• Beyond eutrophication to scarcity
• current institutional fragmentation –lack of clear roles and responsibilities
• Data scarcity: lack of data, lack of transparency
• Research & policy gap: What are the most cost-effective, energy efficient, equitable, environmentally compatible means of using and reusing phosphorus in a given food production & consumption?
Opportunities: Achieving Phosphorus Security• New sustainable technologies and practices for efficient phos-phorus use and recovery
• New synergies between sanitation provision, food security, environmental protection, energy generation & livelihood security
• New partnerships between fertilizer sector, wastewater, urban planning, scientists, etc
• Evolution of the industry from product (fertilizer commodity) to service (soil fertility, food security)
• New actors and policies for ensuring short-and long-term phos-phorus security for crop production
For more information visit www.phosphousfutures.net or www.isf.uts.edu.au or email [email protected]
Hard Landing vs Soft Landing• If we don’t change current phosphorus use trajectory, we are heading for a hard landing of increasing energy, costs and waste, volatile prices, geopolitical tensions, reduced farmer accessto fertilizers and reduced crop yields and food insecurity.
• Softlanding:
- Phosphorus security ensures all farmers have short-and long-term access to sufficient phosphorus to grow enough crops to feed to world, while minimising adverse environmental and social impacts (Cordell 2010)
Framing the Problem: The P Cycle
Notes: An illustration of the P cycle that attempts to render the relative sizes of the dierent terrestrial pools (the marine and lithosphere pools are not drawn to the same scale). The data comes from several global balances, including Smil (2000); Liu et al. (2008); Cordell et al. (2009); Compton et al. (2000). Many of these numbers are back of the envelope estimates. We see that soils repre-sent potentially the largest store. If we naively divide this store by the annual P uptake of agricultural crops, we obtain a store lifespan of 1000 years. But this is a misleading calculation for at least 3 reasons. See next...
Issue 1: Soil P dynamics• I Plant available P (Pa) is only a small fraction of total P (PT )
• I The soil P reservoir is very dynamic: every reaction is reversible (although it may be very slow)
• I The behavior of P is sensitive to soil properties
Notes: Typical diagram conceptualizing P cycling in soils. Routine measures of soil Pa extract the soluble P, the labile P as well as some of the organic P
pool. The rest can be considered more or less “stable”. The extent and rate of each of the depicted transfers will depend on many soil properties. For a long time, it was assumed that soluble inorganic P quickly undergoes irreversible reactions with a number of soil minerals to form stable compounds that are use-less for plant growth. This view has been revised and we now know that most if not all reactions are reversible. Hence, all P compounds can eventually re-enter the Pa pool. At any one time, the equilibrium K = Pa=PT will be dominated by the reaction coecient of the least stable species in the stable pool. If these are very stable, the equilibrium will be low (low P availability).
The soil as an active reservoir of Phosphorus
Framing the problem
The P cycle
The soil as an active reservoir of PhosphorusModeling and implications for management
Marion Dumas, February 20, 2011
The soil as an active reservoir of Phosphorus
Framing the problem
Issue 1: Soil P dynamics� Plant available P (Pa) is only a small fraction of total P (PT )� The soil P reservoir is very dynamic: every reaction is
reversible (although it may be very slow)� The behavior of P is sensitive to soil properties
Issue 1: Implications• Very contrasted results when suppressing mineral P inputs: several decades without response in Sweden (Otabbong et al., 1997), Germany (Gransee and Merbach, 2000), New Zealand (Condron and Goh, 1989)
• Rapid yield collapse in many tropical soils. Bekunda et al. (1997) - experiment in the Sudanian zone of West Africa
Notes: The implications of the soil P dynamics above can be seen in long-term experiments (LTEs). Several LTEs show that yields can be maintained for several decades in the absence of P fertilizer inputs in mid-latitutes/northern soils that are not thoroughly weathered and have been heavily fertilized in the past. In contrast, LTEs in the tropics often show quasi-immediate decline in yields in the absence of P fertilizer inputs (sometimes even if PT is quite high). These dierences are not only due to absence in PT but also to dierences in the bioavailability of P.
Issue 2: Regional Imbalances
Notes: The second reason why the naive calculation of the soil P store’s lifes-pan is misleading is that there are major regional imbalances, some of which are highlighted in this graph (in kgP/ha). Hence, applying a uniform uptake rate to a uniform pool is wrong.
The soil as an active reservoir of Phosphorus
Framing the problem
Issue 1: Implications
Very contrasted results when
suppressing mineral P inputs:
� several decades without
response in Sweden (Otabbong
et al., 1997), Germany
(Gransee and Merbach, 2000),
New Zealand (Condron and
Goh, 1989)
� Rapid yield collapse in many
tropical soils.
Bekunda et al. (1997) - experiment
in the Sudanian zone of West Africa
The soil as an active reservoir of Phosphorus
Framing the problem
Issue 2: Regional Imbalances
12.07.09Sustainable Development Seminar
+ 27
- 7
+ 58
- 4.7
kgP/ha/yrmaps from Ramankutty et al. 2008
Issue 2: Poorly measured reservesThe pool is poorly quantied:• China: PT pool known thanks to Chinese Soil Database (Fig. 1)
• US: continental scale geochemical survey underway
• World: ISRIC World Soil Database contains at most a few hundred measures.
Figure: Spatial distribution of total soil phosphorus density in China (ppm) from 2400 soil proles (Zhang et al., 2005). Total PT pool: 3.5 Gt P.
Notes: The third reason is that the estimate of 40-50 Gt P in the 50 top cm of arable soils is a almost a guess: we do not know what the size of this pool is at the present time. The only precise quantication I am aware of was done for the soils of China (the Chinese soil database is the only one I know of that holds simultaneous measures of Pa and PT ). We see from this calculation that the global estimate may be too high. Because of the three issues above, we need a model to get a better sense of the impact of P flows on agricultural productivity (see next slide).
Notes: Phosphorus cycling through the human ecosystem: This graph rep-resents any region, typically composed of grassland and cropland. Food pro-duction consists of crops, conned livestock fed by fodder and grazing animals fed by grass. � signies the total yield of crops, animals etc. and x stand for the dierent fluxes (e.g. xhw for Human waste) in or out of the pool of . . Ps is the pool of stable P forms, Pa is the pool of bioavailable P forms (e.g. P Olsen or P Bray), ks is the observable rate coecient of the transfer from Pa to Ps while ka is the rate coecient of the opposite transfer.
The soil as an active reservoir of Phosphorus
Framing the problem
Issue 2: Poorly measured PT reserves
The PT pool is poorlyquantified:
� China: PT poolknown thanks toChinese SoilDatabase (Fig. 1)
� US: continental scalegeochemical surveyunderway
� World: ISRIC WorldSoil Databasecontains at most afew hundredmeasures.
Figure: Spatial distribution of total soilphosphorus density in China (ppm) from2400 soil profiles (Zhang et al., 2005).Total PT pool: 3.5 Gt P.
PTPT
Xhw
(recycling)
Human waste Agricultural residues
Livestock manure
y lYield from confined
livestock
Ps
Pa
PT
ks
ka
Cropland topsoil
Ps
Pa
PT
ka
ks
Grassland topsoil
Xhw
(recycling)
Xre
(recycling)
Xyg
(yield)
y T
y c
y g
y fXyf
(yield)
Xer
(erosion)
Xma
(recycling)
Xyc
(yield)
y ga
Xer
(erosion)
Fodder yield
Crop yield
Grass yieldYield from grazing
animals
Inflow/outflow of P from/to soil
Output
Relation
Import/Exports
Boundaries of analyzed region
waste
waste waste
P ores
Xf
(fertilization)
Xf
(fertilization)
PT
Model 1/3
Notes: The dynamics in the previous gure can be expressed quite simply by the following decomposition: dy/dt is the change in annual yields over time, which is equal to the change in yields with respect to a change in Pa ( dy/dPa , also called the yield response) times the change in Pa with respect to a change in (fracdPadPT ) the result of soil P dynamics described above) times the change in over time due to our management of P influxes and outfluxes. From a modeling point of view, the challenge is the middle term, usually mod-eled on small scales by very detailed crop-soil models, but hard to model on large spatial scales.
Yield Response Curve
Notes: The yield response curve is usually quite easy to model, using data from well-monitored plots and tting a function with a plateau to it. ymax is the potential yield in the region of interest once P is no longer a limiting factor. It is consid-ered to be a random variable with distribution f (ymax) (to take into account spatial and temporal heterogeneity of this variable).
Human Managed Mass Balance
Notes: The last term d /dt is the sum of influxes (inputs from recycling and/or mineral fertilizers) and outfluxes (P in harvest and in eroded soil). Erosion and inputs can be measured or can be assumed in the context of scenario analysis. The outflux of P in the harvest is proportional to the harvest obtained from the yield response function.
The soil as an active reservoir of Phosphorus
Model
Model 1/3
The soil as an active reservoir of Phosphorus
Model
Yield Response Curve
0 2 4 6 8 10
01
23
45
67
P available, ppm
yiel
d to
n/ha
f (y) = f (ymax)(1 − aeb×Pa)
The soil as an active reservoir of Phosphorus
Model
Human managed mass balance
dPT
dt= Inputs
− P in harvest
− P in eroded soil
= I (t) − yp(t) − E (t) (1)
PTPT
PT
The Bioavailability Curves 1/3 CS: Calcareous Soils SWS: Slightly Weathered Soils HWS: Highly Weathered Soils
Notes: Times series in over 20 LTEs were reviewed + evidence on the reactions undergone by dierent forms of P in the corresponding soils. I hypothesizedthat there is a non-linear relationship between Pa and and that it should differ systematically across broad categories of soils. In calcareous soils: weakadsorption of P when is low, then the Pa pool increases, until precipitation reactions kick in (early plateau). In highly weathered soils adsorption reactions predominate, with stronger bonds being formed at the lowest P contents, and these bonds gradually become weaker as the pool builds up (thus the slopebetween Pa and becomes steeper). Slightly weathered soils should lie somewhere in between. These relationships are not expected to hold exactly: we expect we can nd a classication of soils for which there exists a well-dened non-linear function f (Pa|PT ) describing Ps behavior. This relationship is only expected to hold on average, thus we formulate it as a conditional average.
The Bioavailability Curves 2/3
Notes: First data set I could nd: uncultivated soils from many locations (N=185) from Sharpley et al. (1987). We can see that the data points from the three classes of soils are potentially drawing the hypoth-esized pattern.
Notes: Time series from LTEs are overlayed on the Sharpley et al. (1987) data (these include no-P experiments where decreases over time, as well as fertilization experiment where increases over time). This gives some support for the hypothesized relationship.
The soil as an active reservoir of Phosphorus
Model
The bioavailability curves 2/3
The soil as an active reservoir of Phosphorus
Model
0 500 1000 1500 20000
5010
015
0Pt
Pa
(Res
inP
, ppm
)
Calcareous soils and some long-term-experimentsUncultivated CS soils, Sharpley & Cole 1987
LTEsWinchmore, Condron & Goh,2000Jindiress, Ryan et al.2008Zhejian province, Zhang et al., 2006
PT
PT
PT
The soil as an active reservoir of Phosphorus
Model
The bioavailability curves 1/3
0 500 1000 1500 2000
050
100
150
200
Hypothesized bioavailability curves
PT (ppm)
Pa
(ppm
)
CS
SWS
HWS
E (Pa|PT ) = g(PT ) = h(1+exp(−r(PT−M)))1/ν
CS: Calcareous SoilsSWS: SlightlyWeathered SoilsHWS: HighlyWeathered Soils
PT PTPT
The Bioavailability Curves 3/3
Notes: The mathematical formulation of the joint probability distribution between Pa and . Both variables are assumed to be lognormally distributed and the parameters of the conditional average Pa | will depend on soil type.
Model 2/3
PTPT
The soil as an active reservoir of Phosphorus
Model
0 500 1000 1500 2000
050
100
150
Pt
Pa
(ppm
)Highly weathered soils and some long-term-experiments
Uncultivated HWS soils, Sharpley & Cole 1987LTEs
Siniloan, Dobermann et al., 2002Matalom, Dobermann et al., 2002Yurimaguas Peru, Beck and Sanchez, 1996
The soil as an active reservoir of Phosphorus
Model
0 500 1000 1500 2000
020
4060
8010
0
Replenishment curve for slightly weathered soils
Total P
Ava
ilabl
e P
Data set of uncultivated soilsSwiss experimental stationsBenchmark european soils
Richards' growth curve
The soil as an active reservoir of Phosphorus
Model
The bioavailability curves 3/3
0 500 1000 1500 2000
020
4060
8010
0
Replenishment curve for slightly weathered soils
Total P
Ava
ilabl
e P
Data set of uncultivated soilsSwiss experimental stationsBenchmark european soils
Richards' growth curve
f (PT ) =1
PTσT
√2π
exp(−(log(PT ) − µT )2
2σT) (2)
f (Pa|PT ) =1
Paσa
√2π
exp(−(log(Pa) − µa)2
2σa) (3)
where µa = log(g(PT )) = h − 1
ν(1 + e−r(PT−M)) (4)The soil as an active reservoir of Phosphorus
Model
Model 2/3
f (PtT ) = f (Pt−1
T +1
ρD(−y t−1
p − E t−1 + I t−1) (5)
f (Pta) =
∫f (Pt
a |PtT )f (Pt
T )dPtT (6)
f (y t) =
∫f (ymax)(1 − a exp(b × Pt
a)dPta (7)
Notes: The dynamic model including the feedback from outflow of P in theharvest. The mass balance updates the distribution f ( ), the bioavailability function allows to deduce the distribution f (Pa) and this allows to estimate the distribution of yields.
Model 3/3
Notes: The dynamic probabilistic model is perhaps better understood in this graphical form. All variables are expressed probabilistically because of the heterogeneity and uncertainty associated with them. In particular, the flows of P in crop residues, manure and human waste must also be linked to the amount of P present in the harvests of crop (due to mass balance).
• As a toy model to answer stylized questions illuminating sustainability of P cycle
• As information rich simulation of the P cycle in particular regions
Given a region’s initial endowment of , what would be the decline of a represen-tative crop in absence of mineral P fertilizer?
Notes: This simple large-scale model could shed light on how dependent dier-ent regions are on inputs of P. Here we see time series for two dierent scenarios in the three classes of soils, using the hypothesized relationships and assuming no P fertilizer inputs. The black lines represent the average and the grey lines represent the condence intervals. We see that yields are not very sensitive to declines in due to the harvests, because this is in part buered by the Pa pool and the fact that at high , P is not limiting.
0 50 100 150
050
010
0015
0020
00
Pt i
n pp
m
0 50 100 150
050
010
0015
0020
00
Pt i
n pp
m
0 50 100 150
050
100
150
200
Pa
in p
pm
0 50 100 150
050
100
150
200
Pa
in p
pm
0 50 100 150
01
23
45
yiel
ds in
ton/
ha
0 50 100 150
01
23
45
yiel
ds in
ton/
ha
Time Time
High Initial Total soil PConventional tilling
Low Initial Total soil PNo-till
mean HWSmean CSmean SWSCI HWSCI CSCI SWS
Parameters of theavailability functionas in Fig 2Yield response curveparameters are: a=0.98, b=0.22
from barley yield data
Given a
region’s
initial
endowment
of PT , what
would be the
decline of a
representa-
tive crop in
absence of
mineral P
fertilizer?
The soil as an active reservoir of Phosphorus
Model
Model 3/3
PT
PT
PT
PT
How much mineral P is necessary to bring the soils of a region to a point where replacement of P taken up by harvest by means of recycling is suffcient?
Notes: Looking at the joint distribution Pa; allows us to estimate the proportion of soils that are decient in P. Deciency is dened in terms of a critical value ;crit under which Pa becomes limiting. ;crit varies from soil to soil. We can estimate how much P would have to be added to the soil to achieve > ;crit. In black is the joint distribution at t=0 and in grey at t=150 (years). In the second scenario, there is acute P deciency.
How much mineral P is necessary to bring the soils of a region to a point where replacement of P taken up by harvest by means of recycling is suffcient ?
PT
PT PT
PT
PT
0 1000 2000 3000 4000 5000
010
020
030
040
050
0
HWS t=0: 22% area deficient in P
t=150: 50% area deficient in P
0 1000 2000 3000 4000 5000
010
020
030
0
Pa in
ppm
CS t=0: 0% area deficient in P
t=150: 3% area deficient in P
0 1000 2000 3000 4000 5000
020
040
060
0 SWS t=0: 0.2% area deficient in P
t=150: 10% area deficient in P
Pt in ppm
Initial ConcentrationFinal Concentration
Threshold for PtThreshold for Pa
Scenario 1: High initial P and high erosion
Parameters of theavailability functionas in Fig 2Yield response curveparameters are: a=0.98, b=0.22from barley yield data
How much
mineral P is
necessary to
bring the
soils of a
region to a
point where
replacement
of P taken up
by harvest by
means of
recycling is
sufficient ?
0 500 1000 1500 2000
050
100
150
200
HWS t=0: 93% area deficient in P
t=150: 100% area deficient in P
0 500 1000 1500 2000
050
010
0015
00
Pa in
ppm
CS t=0: 0.09% area deficient in P
t=150: 95% area deficient in P
0 500 1000 1500 2000
020
060
010
00
SWS t=0: 24% area deficient in P
t=150: 99% area deficient in P
Pt in ppm
Initial ConcentrationFinal Concentration
Threshold for PtThreshold for Pa
Scenario 2: Low initial P and low erosion
Parameters of theavailability functionas in Fig 2Yield response curveparameters are: a=0.98, b=0.22from barley yield data
How much
mineral P is
necessary to
bring the
soils of a
region to a
point where
replacement
of P taken up
by harvest by
means of
recycling is
sufficient ?
Case Study: Canton Fribourg 1/2
Notes: This model could potentially be used for more localized and detailed case studies. Here is an example using data on soil P content, erosion and yields from Canton Fribourg.
Case Study: Canton Fribourg 2/2
Tentative Conclusions• Initial conditions are very important: key role of soils’ mineral capital
• P-enriched regions may be able to maintain stable yields even in the event of shortage: adaptation time
• P-enriched regions could maintain high productivity by closing the loop
• P-poor regions cannot rely on closing the loop to maintain high yields
Outlook• Indicates gaps in our knowledge of the P cycle:
- The size of the PT stock
- The link between PT and bioavailable P
• Could assess sensitivity and productivity potential of dierent regions
• Especially when combined with distribution of other key factors of production
• Highlights the role of soils as P capacitors:
- Assistance in the design of new stocks of P for the future?
The soil as an active reservoir of Phosphorus
Applications
Case study: Canton Fribourg 1/2
0 20 40 60 80 100
0.00
0.04
0.08
Evolution of Available P, ppm
Den
sity
yr 1
yr 100
0 500 1000 1500 2000 2500
0.00
000.
0015
Evolution of Total P, ppm
Den
sity
yr 1
yr 100
Figure: Simulation in simplest scenario: no recycling, just crop uptake
The soil as an active reservoir of Phosphorus
Applications
Case study: Canton Fribourg 2/2
0 20 40 60 80 100
0.0
0.4
0.8
Years
Inde
x of
Rel
ativ
e yi
eld
0 20 40 60 80 100
010
2030
40
Years
Ava
ilabl
e P
, ppm
Figure: Large soil stocks: limited sensibility.
Tentative Criteria to Evaluate Sustainability of the Exit-phase of Scenarios• Security: Ensure large enough extent of soils in the world have PT > Pcrit /T to feed world population
• Precaution: Ensure enough ores remain to counterbalance unavoidable dissipation of soil P through low level erosion and losses in transformation processes.
• Freedom: Ensure enough ores remain at any point in time to allow enrichment of soils in any region where PT < Pcrit /T whenever population desires to be agriculturally productive.
SourcesSmil, V. (2000). Phosphorus in the environment: Natural flows and human interferences. Annual Review of the Energy and the Environment, 25:53-88.
Liu, Y., Villalba, G., Ayres, R., and Schroder, H. (2008). Global phosphorus flows and environmental impacts from a consumption perspective. Industrial Ecology, 12(2):229-247.
Cordell, D., Drangert, J., and White, S. (2009). The story of phosphorus: Global food security and food for thought. Global Environmental Change, In press.
Compton, J., Mallinson, D., Glenn, C., Filippelli, G., Foellmi, K., Shields, G., a and Zanin, Y. (2000). Variations in the global phosphorus cycle.
Zhang, C., Tian, H., Liu, J., Wang, S., Liu, M., Pan, S., and Shi, X. (2005). Pools and distributions of soil phosphorus in China. Global Biogeochemical Cycles, 19(GB1020, doi:10.1029/2004GB002296).
Sharpley, A., H., T., and Cole, C. (1987). Soil phosphorus forms extracted by soil tests as a function of pedogenesis. Soil Sci. Soc. Am. J., Vol. 15.
Otabbong, E., Persson, J., Iakimenko, O., and Sadovnikova, L. (1997). The Ultuna long-term soil organic matter experiment. Plant and Soil, 195:17{23.
Bekunda, M., Bationo, A., and Ssali, H. (1997). Soil fertility management in africa: A review of selected research trials. In Buresh, R., Sanchez, P., and Calhoun, F., editors, Replenishing Soil Fertility in Africa. Soil Science Society of America.
Gransee, A. and Merbach, W. (2000). Phosphorus dynamics in a long-term P fertilization trial on luvic phaeozem at Halle. J. Plant Nutri. Soil Sci., 163:353-357.
Condron, L. M. and Goh, K. (1989). Eects of long-term phosphatic fertilizer applications on amounts and forms of phosphorus in soils under irrigated pasture in new zealand. Journal of Soil Science, 40:383-395.
Sustainable Phosphorus in Agriculture, Soils and WatersPhil Haygarth and many others, Centre for Sustainable Water Management,Environment Centre, Lancaster University, United Kingdom
2. MOBILISATION describes the start of the journey from soil or source P, either as a solute (solubilised) or attached to colloids and particles (detached)
3. DELIVERY/TRANSPORT describes the complex journey the solutes, colloids or particles take after mobilisation to connect to the stream
1. SOURCES include fertilizer applications, defecation from grazing animals, spreading of manure on soils
Infiltration-excess flow
Saturation-excess flow
Sub-surface flow
4. IMPACT describes the connection with the biological impact of the diffuse substance in the receiving water
The phosphorus ‘transfer continuum’ – from land to water
(Haygarth et al., STOTEN, 344, 2005)
INPUTS
grazing16.5
excreta9.6
cut - silage16
slurry & FYM 32
SOIL
OUTPUTS
58 kg TP/ha
33 kg TP/ha
Haygarth et al (1998) SUM
P farm balances often in surplus
0
1
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0 10 20 30 40 50 60 70Microbial P (mg kg-1 dry soil)
Wat
er e
xtra
ctab
le o
rgan
ic P
in
crea
se (m
g kg
-1 d
ry s
oil)
Soil wetting and drying releases organic P to solution from biomass
China has now become the largest country in consuming and producing P fertilizer in the world.
Phosphorus and Sustainability in Agriculture, Soils and Waters• P is limited in supply yet an essential contributor to agriculture & food production –fertilizer and animal feeds
• P is generally inefficiently used in soils)
• P leaks from land to waterways
Phosphorus Imperatives: What We Must Do
What we must do• Bring it back from rivers and estuaries onto land
• Strategic use of fertilisers and manure
• Make better use of P in soils and crops
• Reduce leaks to water
How we should start this• Raise awareness
• Cross discipline effort
• Identify priorities -global and regional audits
twitter@ProfPHaygarth
Phosphorous Issues: Initial thoughts from
an Environmental EconomistCatherine L. Kling
Department of EconomicsCenter for Agricultural and Rural Development
Iowa State University
Sustainable Phosphorous Summit: February 3, 2011
Phosphorous Issues: Init ial Thoughts From an Environmental Economist
Catherine L. Kling, Department of Economics, Center for Agricultural and Rural Development, Iowa State University
My Research Interests: Phosphorous as an Externality
• Externality: unintended side effect of economic activity:
- generally not accounted for in a market
- Phosphorous runoff from agricultural cropping systems is an externality
• Value of lost ecosystem services from water quality degradation
• Policy design: conservation programs (farm bill, etc.) using watershed models integrated with economic decisions
Other economic concepts central to P sustain-ability• Optimal use of exhaustible and renewable resources
- When will markets appropriately allocate resources across time in this case?
- When is market intervention necessary for social welfare?
• Technology adoption and incentives
- Does market provide adequate incentives for recycling, development of substitutes, etc.
Example of Watershed Modeling and Policy Design:Least Cost Control of Agricultural Nutri-ent Contributions to the Gulf of Mexico Hypoxic ZoneSergey Rabotyagov, T. Campbell, M. Jha, H. Feng, P. Gassman, L. Kurkalova, S. Secchi, and C. Kling “Least Cost Control of Agricultural Nutrient Contributions to the Gulf of Mexico Hypoxic Zone,” Ecological Applications 20 (2010):1542-1555
Hypoxia=Dead Zone
• Oxygen-depleted hypoxic (dead) zones have increased exponentially since the 1960s
• Over 400 hypoxic areas worldwide, affected area of 245,000 km2 (Diaz and Rosenberg, 2008)
• Naturally occurring, but far larger due to anthropogenic sources
• Hypoxic zones result in stressed marine and estuarine systems, mass mortality and dramatic changes in the structure of marine communities (Diaz and Rosenberg, 1995).
Phosphorous Issues: Initial thoughts from
an Environmental EconomistCatherine L. Kling
Department of EconomicsCenter for Agricultural and Rural Development
Iowa State University
Sustainable Phosphorous Summit: February 3, 2011
Historic Size of Hypoxic Zone: 1985-2008
Phosphorous Issues: Initial thoughts from
an Environmental EconomistCatherine L. Kling
Department of EconomicsCenter for Agricultural and Rural Development
Iowa State University
Sustainable Phosphorous Summit: February 3, 2011
Gulf Hypoxia: Emission Sources• Causes: nutrients from Mississippi river, nitrates and phosphorous,
• Limiting nutrient may now be P (scientific debate continues)
• Major Contributors:
- UMRB (1+2) = 43%N, 41%P
- Ohio-Tennessee (6+7) = 41%N, 59%P
Local Water Quality
• Nutrients (esp. phosphorous) and sediment primary source
• Agriculture accounts for over 50% of impairments (EPA)
• Multiple conservation practices can ameliorate(Land retirement, conservation tillage, grassed waterways, contours, terraces)
Modeling of Gulf Hypoxia
Phosphorous Issues: Initial thoughts from
an Environmental EconomistCatherine L. Kling
Department of EconomicsCenter for Agricultural and Rural Development
Iowa State University
Sustainable Phosphorous Summit: February 3, 2011
10
Watershed Schematic
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Grafton
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Watershed Schematic
Phosphorous Issues: Initial thoughts from
an Environmental EconomistCatherine L. Kling
Department of EconomicsCenter for Agricultural and Rural Development
Iowa State University
Sustainable Phosphorous Summit: February 3, 2011
Consequences of seeking a 30% reduction in P and NO3• Conservation and Land use to achieve reduction
- N fertilizer reductions
- grassed waterways (extensive)
- terraces (combined with N fertilizer reductions)
- additional (substantial) land retirement
• The annual additional cost is estimated to be $ 1.4 billion (more than quadrupling baseline cost)
• May important caveats to results and modeling framework, but proof of concept of approach
Example of Ecosystem Services Research:Eco-nomic Value and Recreational Use of Iowa LakesCatherine Kling, Joe Herriges, John Downing, Kevin Egan, and Greg Colson. Funding from EPA Star grant, Iowa DNR, and CARD
Measuring Economic Value of Iowa Lakes• DNR provided a list of 35 priority Lakes for possible restoration
- Resulting lake changes were projected assuming
- a 70% reduction in total nitrogen, total phosphorous and suspended solids
- a 90% reduction in cynobacteria
- corresponding changes in Secchidepth, chlorophyll, and total phytoplankton
A range of lake changes were considered, including less major changes
Single Lake Rankings Sorted By Total Net Bene-fits ($million)
Ranking Lake TB1 Big Creek 755.762 Brushy Creek 517.203 Hickory Grove 277.804 Lake McBride 226.215 Clear Lake 202.936 Lake Geode 166.117 Three Mile 163.678 Easter 113.489 Lake Ahquabi 88.5510 Little Wall 81.8511 Lake Anita 69.6712 Kent Park 61.9913 Springbrook 61.7914 Red Haw 55.1015 Don Williams 66.14
Using Travel Pattterns to Reveal Valuation
Phosphorous Issues: Initial thoughts from
an Environmental EconomistCatherine L. Kling
Department of EconomicsCenter for Agricultural and Rural Development
Iowa State University
Sustainable Phosphorous Summit: February 3, 2011