Phosphorus Forms in Manure:
Differences with Animal Species and Diet
Barbara Cade-Menun
Semi-Arid Prairie Agriculture Research Centre
Swift Current, SK
What is Phosphorus?
15
P
30.97
2-8-5
+3
+5
-3
• 10th most abundant element on earth
• essential nutrient for life
• most abundant P mineral is apatite (Caphosphate)
• secondary minerals: Fe- and Alphosphates
• Isotopes: 31 P (32 P, 33 P)
• No significant gaseous forms in nature
Why Study Phosphorus?
No P
P Added
International Rice Research Institute
Lake 226, Experimental Lake Study, Ontario, 1973
Manure Phosphorus
•
Manure is a valuable nutrient source
•
However:
• The N:P ratio doesn’t match plant needs; N-rate
application over-applies P
• Land disposal of manure can over-apply P
•
Excess P from manure is lost in runoff
•
To avoid excess P, we need to know manure P
concentrations and forms
Orthophosphate
OH
HO - P = O
OH
H2PO4-
H3PO4
p ka=1.96
•
•
p ka=6.80
HPO42-
PO43p ka=12
Predominant inorganic P form in soils, water
Most bioavailable P form: P form used by plants
Pyrophosphate, Polyphosphate
O
NH2
O
O
O - P - O - P - OO-
O
O
N
O-P- O-P- O-P - O
PYROPHOSPHATE
O-
O-
CH2
O
H
O
O
O
O
O - P - O - P - O -P - O - P - O - etc
O-
O-
O-
O-
POLYPHOSPHATE
C
N
C
CH
CH
OO-
C
N
N
H
H
H
OH
OH
ATP
Bioavailable P; Energy-rich bonds
Orthophosphate Monoesters
inositol phosphates, sugar phosphates, mononucleotides, ATP
-O
-O-P-O
O
O
-O-P-O
HO O
-O-P-O
-O
OO
-O-P-O
-O
OO-P-OO
O
O-P-OO-
Inositol Hexaphosphate
(IHP, Phytate)
H2C-O-P-OH
HO
H
OH
O O
H
H
H
OH
OH
Glucose 6-phosphate
Vary in bioavailability
Orthophosphate Diesters
phospholipids, RNA, DNA, teichoic acid
CH2
CH2 – O – C – (CH2)nCH3
H
BASE
H
H
O
HC- O – C – (CH2)nCH3
H
O
O-
CH3
O
CH2 – O – P –O- CH2 – N – CH3
O
O
O
P
-O
O-C
D-Glucose -
O-C
HO - P = O
D-Alanine
-O-C
D-Alanine
-O-C
O
CH3
Phosphatidyl Choline
H
O
DNA
CH2 O BASE
H H
H
H
O H
O-
H2 C - O - P - O
Ribitol
O
HO - P = O
Vary in bioavailability
O
Ribitol Teichoic Acid
(B. subtilis)
Phosphonates
CH3
Fosfomycin
H
H
O
C
C
P
O
OH
Includes glyphosate (Round-Up)
Bioavailability unknown
OH
Manure Phosphorus
•
Sources of P forms in manure:
• Orthophosphate: diet, digestion of P forms
• Polyphosphates: microbes
• Monoesters: diet, microbes, digestion
• Diesters: microbes (diet)
• Phosphonates: microbes
Manure Phosphorus
Why do the specific P forms in manure matter?
O-
CH2 – O – C – (CH2)nCH3
H2C-O-P-OH
HO
H
OH
H
O O
H
O
HC- O – C – (CH2)nCH3
OO
H
OH
CH3
CH2 – O – P –O- CH2 – N – CH3
OH
O
-O
-O-P-O
OO
O-P-OO
O
-O-P-O O
-O-P-O
-O
O
O
HO
-O-P-O O-P-OO-O
Glucose 6-phosphate
Phytate
CH3
Phosphatidyl Choline
P forms vary in their
bioavailability and
reactivity
Manure Phosphorus
Which manure P forms do we care about most?
-O
-O-P-O
OO
O-P-OO
O
O
-O-P-O
-O-P-O
-O
O
O
HO
O-P-O-O-P-O
O-O
OH
HO - P = O
OH
Orthophosphate
•
•
Bioavailable by animals,
plants, algae,
Excess easily lost in runoff
Phytate
•
•
•
•
Storage compound in seeds and
grains
Not used by animals or plants
Available to algae
Binds tightly in soils
Manure Phosphorus
•
Factors affecting manure P forms and concentrations:
• Animal species
• Diet
• Dietary supplements
• Manure storage
Effects of Animal Species on Manure P
Dairy
Cattle
Sheep
Orthophosphate
Phytate
Other P forms
Chicken
Turkey
Pig
Deer
P Forms in Diet, Feces and Manure
Analyzed feed, feces and
manure of cows
P forms changed after
digestion and composting
IHP=phytate
From: Toor et al. 2005 J. Environ. Qual. 34:1380-1391
Effect of Animal Diet on Feces P
Feces of dairy cows with
different diets (total mixed
rations, grazing, grain)
Changing animal diet alters
manure P forms
From: McDowell et al. 2008 J. Environ. Qual. 37:741-752.
Effects of Animal Diet on Manure P
Chicken feces, fed various grains, phytase
Corn
Wheat
Orthophosphate
Corn
Phytase
Phytate
Wheat
Phytase
From: Leytem et al. 2008 Poultry Sci. 87:2466-24762
Barley
Oats
Other P forms
Oats
Phytase
Barley
Phytase
Effects of Storage on Manure P
Dairy
Solid
Compost
Lagoon
Poultry
Wet
Compost
Orthophosphate
Dry
Compost
Phytate
Other P forms
From: Hansen et al. 2004 J. Environ Qual. 33:1521-1527; McGrath et al. 2005: J. Environ Qual. 34: 1896-1909.
Effects of Treatment on Manure P
Swine manure,
biodigested for methane
Undigested
Digested
Poultry Manure Transects
Phytic Acid
Orthophosphate
Observed a shift from phytic acid to orthophosphate
Question: Is phytic acid transformed or transported?
From Hill and Cade-Menun 2009 J. Environ. Qual. 38:130-138.
Take-Home Message
•
•
•
•
•
Many P forms in manure, soil, water
P forms vary in their bioavailability and reactivity
P forms in manure will change with diet, storage,
treatment
Dairy and poultry: many studies
Cattle: few studies; little known about the effects of
supplements (e.g. distiller`s grains)
Manure is a valuable nutrient source that is
underappreciated!