phosphorus chemistry in soils and response to fertilizer and manures april leytem usda/ars
TRANSCRIPT
Phosphorus Chemistry in Phosphorus Chemistry in Soils Soils andand
Response to Fertilizer and Response to Fertilizer and ManuresManures
April Leytem
USDA/ARS
The Phosphorus The Phosphorus CycleCycleThe Phosphorus The Phosphorus CycleCycle
Animalmanures
and biosolids Mineralfertilizers
Crop harvest
Runoff anderosion
Leaching
Organic phosphorus•Microbial•Plant residue•Humus
Primaryminerals(apatite)
Plant residues
Plantuptake
Soil solutionphosphorus•HPO4
-2
•H2PO4-1
Secondarycompounds
(CaP, FeP, MnP, AlP)
Mineralsurfaces
(clays, Fe and Al oxides,
carbonates)
Mineralsurfaces
(clays, Fe and Al oxides,
carbonates)
InputsComponent Outputs
Atmosphericdeposition
PPI
PrecipitationPrecipitation
DissolutionDissolution
DesorptionDesorption
AdsorptionAdsorption
Wea
ther
ing
Wea
ther
ing
Immobilization
ImmobilizationMineralization
Mineralization
• Estimates of 800 million hectares of calcareous soils worldwide
• Generally they are low in P due to fairly insoluble Ca-P minerals
• The concentration of available P continues to decrease over time
Facts About Calcareous Facts About Calcareous SoilsSoils
Soil P FractionsSoil P Fractions
MineralPi
MineralPi
Labile Pi & Po
Labile Pi & Po
SolutionPi & Po
SolutionPi & Po
Mineral P >>> Labile P >> Solution-PMineral P >>> Labile P >> Solution-P
0
20
40
60
80
100
0 200 400 600 800
Equilibrium P (mg P L-1)
So
rbe
d P
(mm
ol
P k
g-1
) Experimental Data
Freundlich
Precipitation
Phosphorus Sorption in Soils
0 ppm P0 ppm P
Calcite Equilibrat
ed for 10 Days
Calcite Equilibrat
ed for 10 Days
10 ppm P10 ppm P
Calcite Equilibrate
d for 10 Days
Calcite Equilibrate
d for 10 Days
50 ppm P50 ppm P
Calcite Equilibrate
d for 10 Days
Calcite Equilibrate
d for 10 Days
The quantity of P sorbed on calcite depends largely on its surface area
Pure calcite has low surface area (1 to 2 m2/g)
Soil calcite has surface area ranging from 16 to 200 m2/g
(due to ongoing dissolution, reprecipitation, and incorporation of impurities)
On pure calcite, sorption occurs on ~5% of the surface beforeadsorption clusters serve as nuclei for Ca-P precipitation
• First few weeks, P initially precipitates First few weeks, P initially precipitates as MCP…. Then DCPDas MCP…. Then DCPD
• After 3 to 5 months, octacalcium phosphate After 3 to 5 months, octacalcium phosphate precipitatesprecipitates
• After 8 to 10 months, tricalcium phosphate After 8 to 10 months, tricalcium phosphate formsforms
• Long periods (years) hydroxyapatite Long periods (years) hydroxyapatite minerals form…minerals form…
(mineral with lowest solubility controls P (mineral with lowest solubility controls P concentration- while intermediates are concentration- while intermediates are unlikely to persist)unlikely to persist)
Traditional ConceptsAdding P Fertilizer to High pH/ High Calcium Soils
Incubation Period (days)
Fert
iliz
er
P A
vailab
ilit
y
(Fra
cti
on
of
Ad
ded
P S
till E
xtr
acta
ble
)
(Sharpley et al., 1989)
Phosphorus Availability Decreases Over Time
Average of 44% P sorptionbetween 30 and 180 days following application
Potato P Recommendations
0
100
200
300
400
500
0 10 20 30 40
STPC
P R
ate
, lb
s P
2O
5/A
Soil Test Calibration Studies
0 Lime
12% Lime
P R
ate
, lb
s P
2O
5/A
UI, 2001
Relative Y ield Response, Potatoes
0
20
40
60
80
100
120
0 10 20 30 40
STPC
Re
lati
ve
Yie
ld, %
Soil Test Correlation Studies
0 Lime
12% Lime
UI, 2001
University of Idaho: Potato P Recommendations take into account the free lime content of the soil
Leytem and Westermann, 2003
Majority of the soils had a break-point at approx. 150 ppm.
low P (<150 ppm), P sorption with oxides, clay surfaces, and organically-complexed metals (Fe & Mn)
high P (>150 ppm), precipitation reactions
0
30
60
90
0 200 400 600 800
0
30
60
90
0 200 400 600 800
Sorb
ed P
(m
mol P k
g-1)
Equilibrium P (mg P L-
1)
r2 = 0.860
10
20
30
40
0 300 600 900 1200 1500
NTA (Mn + Fe), mmol kg-1
Xt,
mm
ol P
kg-1
Leytem and Westermann, 2003
Organically complexed Mn and Fe were the primary factors controlling P sorption
0
20
40
60
80
100
0 200 400 600 800
Equilibrium P (mg P L-1)
So
rbe
d P
(mm
ol
P k
g-1
) Experimental Data
Freundlich
Precipitation
Phosphorus Sorption in Soils
How Can organically complexed metals affect P adsorption?
P is complexed with OM through metal bridges?
• OM interferes with Ca-P and metal oxide precipitation by coating the calcite surfaces?
PO4
Robbins and Westermann previously showed that organic carbon enhanced the solubility and extractability of added P in calcareous soils-
showing that there are many mechanisms regulating P sorption
and solubility
Organic ligands affect P sorption- they compete with orthoP for similar sites on the surface of oxides.
Organic matter may also chelate metals and prevent reactions between metals and P
How does this relate to Humic Acid additions?
Far West Fertilizer Meeting, 2004: “Never add P fertilizer to a Calcareous soil without adding Humic Acid with it”
Organic Matter and P Interactions
University of Idaho experience with Humic Acid (2003 report)
If Organically Complexed If Organically Complexed Metals Control P Solubility, Metals Control P Solubility,
What Happens When We Add What Happens When We Add Manure?Manure?
Myths About P and Myths About P and ManuresManures
• Manure P is organic PManure P is organic P
• Organic P is more soluble and Organic P is more soluble and more readily leached than more readily leached than inorganic Pinorganic P
• Manure is a greater threat to water Manure is a greater threat to water quality than fertilizer P because it quality than fertilizer P because it is organic Pis organic P
HO P OH
O
OH
HO P O
O
OH
P OH
O
OH
Organic P
Inorganic P
Phytic Acid ATP (monoester)
Inorganic Orthophosphate
Pyrophosphate
OPO3H2
H2O3PO OPO3H2
OPO3H2
H2O3PO
OPO3H2
Some Typical Organic P Compounds in Manures
0
100
200
300
400
500
600
0 50 100 150 200
Equilibrium P (mg P mL-1)
P So
rbed
(m
g P
kg-1)
Phytic Acid
ATP
ADP
AMP
OrthoP
P Sorption in Soils P Sorption in Soils
HO P OH
O
OH
HO P O
O
OH
P OH
O
OH
Organic P
Inorganic P
Phytic Acid ATP (monoester)
Inorganic Orthophosphate
Pyrophosphate
OPO3H2
H2O3PO OPO3H2
OPO3H2
H2O3PO
OPO3H2
Some Typical Organic P Compounds in Manures
0%
20%
40%
60%
80%
100%
120%
SL SS- HP DL BS- grass DC PL
OrthoP Monoesters PyroP Phytic Acid
Manure P CompositionManure P Composition
How does manure How does manure behave as a fertilizer behave as a fertilizer
compared to inorganic compared to inorganic fertilizer? fertilizer?
(Leytem & Westermann, 2005)
Soil Test P
0
25
50
75
100
125
RP
E O
lsen
P
BS DC DL POLYP MAP MCP
0
1
2
3
4
5
Dry
ma
tte
r (g
)
C BS MCP DL DC MAP POLYP
Response in STP and Plant Response in STP and Plant GrowthGrowth
Plant P UptakePlant P Uptake
Although the soil test P increased less when we applied manures….
The amount of P taken up by the plants was greater for some manures than fertilizers
0
2
4
6
8
10
P u
pta
ke (
mg
)
C BS MCP DC MAP DL POLYP
P SourceP SourceRPERPE
OlsenOlsen
RPRP
UptakUptakee
EfficiencyEfficiency
Dairy LiquidDairy Liquid 62.662.6 113.1113.1 1.81.8
Beef SolidBeef Solid 26.526.5 59.559.5 2.242.24
Dairy Dairy CompostCompost 49.049.0 149.9149.9 3.053.05
MCPMCP 100.0100.0 100.0100.0 1.01.0
MAPMAP 85.385.3 145.0145.0 1.691.69
Phosphorus Uptake EfficiencyPhosphorus Uptake Efficiency
Do these trends Do these trends change in the field? change in the field?
Olsen P with Depth in Field Olsen P with Depth in Field Plots Plots
0
10
20
30
40O
lse
n P
(p
pm
)
0-6" 6-12" 12-18"
Control
Compost
Manure
Fertilizer
aa
b
c
a
b
b
c ab ab ab
Fertilizer and manure behave similarly in the topsoil, but fertilizer P enriched STP in the subsurface compared to manure
and compost
Runoff P from Field Plots Runoff P from Field Plots
0
50
100
150
200
250
Ru
no
ff P
(m
g)
ControlCompostManureFertilizer
a
c
bcab
Fertilizer and manure had similar runoff P while compost and control were lower but similar
r2 = 0.82
0
50
100
150
200
250
0 10 20 30 40
Olsen P (ppm)
Ru
no
ff P
(m
g)
Cumulative runoff P was closely correlated with the bicarbonate STP
P Uptake from Field Plots P Uptake from Field Plots
0
10
20
30
P u
pta
ke
(k
g)
Control
Compost
Manure
Fertilizer
a
b
a a
The addition of fertilizer, manure and compost increased the P uptake by the crop, but they did not differ significantly
STP over 20 ppm does not require fertilizer addition
Is it really all just Is it really all just about the P in about the P in
manures or is there manures or is there something else going something else going
on? on?
1313C NMR of WS-CarbonC NMR of WS-Carbon
Chemical shift (ppm)
050100150
050100150
050100150
Dairy Compost
Dairy Manure
Dairy Liquid
Solid manures dominated by aromatic and
aliphatic compounds (larger more
stable)
Liquid manures dominated by
carbonyl functional groups
(smaller more reactive)
r2 = 0.90
0102030405060708090
0 50 100 150
C:P Ratio of Manures
Ols
en
P (
mg
kg-1
)
The Carbon in Manures The Carbon in Manures Influences the P solubility of Influences the P solubility of
the Soil the Soil
r2 = 0.71***
0
20
40
60
r2 = 0.75***
0
20
40
60
0 20 40 60
Microbial P mg kg-1
Ols
en
P m
g k
g-1
W
SP
mg
kg
-1
Effect of Microbial P on WSP and Effect of Microbial P on WSP and Olsen POlsen P
P Release Over Growing Season From P Release Over Growing Season From Manure, Compost and FertilizerManure, Compost and Fertilizer
0
10
20
30
40
50
0 2 4 6 8 10 12 14
Weeks
RPE
PRS
pro
bes
compost
manure
fertilizer
C:P = 15
C:P = 45
C:P = 0
SummarySummary
• Manure with similar P composition applied at Manure with similar P composition applied at same total P ratessame total P rates• Differences in P solubility dominated by the Differences in P solubility dominated by the
amount of C added with the manure treatmentamount of C added with the manure treatment
• Manures increase STP less than fertilizer Manures increase STP less than fertilizer treatments but have a greater plant P uptake than treatments but have a greater plant P uptake than fertilizerfertilizer
ImplicationsImplications
• We need to consider the amount of C in We need to consider the amount of C in calcareous soils when determining P calcareous soils when determining P sorption/availabilitysorption/availability
• When we make P risk assessments in When we make P risk assessments in calcareous soils with manure incorporation, calcareous soils with manure incorporation, we need to consider the effects of the C we need to consider the effects of the C content and composition of manures content and composition of manures
• Microbial P has a large influence on soluble P Microbial P has a large influence on soluble P and this needs to be further exploredand this needs to be further explored
So Why the P Problems with So Why the P Problems with Manures?Manures?
N:P ratios don’t match upN:P ratios don’t match up Crops want a ratio of about 5:1Crops want a ratio of about 5:1 Manure ratios are typically closer to 2:1Manure ratios are typically closer to 2:1 Therefore when applying manure on an N based Therefore when applying manure on an N based
rate we are always over applying Prate we are always over applying P Overfeeding of P in animal operationsOverfeeding of P in animal operations
Low P availability of feeds in monogastrics leads to P Low P availability of feeds in monogastrics leads to P supplementationsupplementation
Dairies traditionally overfeed P for insurance Dairies traditionally overfeed P for insurance Cost of transporting manuresCost of transporting manures
Over application of manures on sites closest to manure Over application of manures on sites closest to manure generation/storagegeneration/storage
Northwest Irrigation and Northwest Irrigation and Soils Research LaboratorySoils Research Laboratory
Kimberly, IdahoKimberly, Idaho
USAUSA