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http://www.extension.org/67731 The solubility of phosphorus (P) and low nitrogen(N):P ratio of poultry litter present environmental challenges when using this resource to supply nutrients to crops and forages. Here, we explore the use of chitosan to reduce water extractable P (WEP) in poultry litter and potentially increase the N:P ratio. Chitosan is derived from chitin, which is a waste product from the commercial shellfish industry; chitin is processed into chitosan through deacetylation, removing acetyl groups from this long-chained molecule. Chitin has been successfully used in manure separation and flocculation in wastewater treatment processes, as well as immobilizing algae in wastewater streams to uptake nutrients.
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Brian E. HaggardIain M. Bailey
David A. Zaharoff
Arkansas Water Resources Center
Department of Biological and Agricultural
Engineering
Department of Biomedical Engineering
University of Arkansas
WHAT HAPPENS WHEN YOU MIX CHITOSAN
WITH POULTRY LITTER?
DZ walked into my office, and simply asked what’s this phosphorus and poultry production problem we have? I asked if he wanted the short or long version…
DZ said what if I have a chemical that can remove phosphate from aqueous solution, would that help?
I said, tell me more…
HOW DID THIS IDEA COME ABOUT?
This lab focuses on the development of platforms to deliver vaccines
One of the most promising platforms has been chitosan
DZ RUNS THE LAB OF IMMUNOTHERAPY AND VACCINE DELIVERY.
Chitin Processed crustacean shells Highly abundant product
Chitosan Deacetylated form of chitin Varies by molecular weight
(MW) and degree of deacetylation (DD)
Deacetylation exposes the molecule’s amine groups This creates a large, cationic
polysaccharide Its structure makes it highly
reactive with a broad range of chemicals in aqueous solutions
WHAT IS CHITOSAN?
Current applicationsCommercial wastewater treatment
Manure separationAlgae flocculation in eutrophic waters
Algae immobilization for nutrient removal
Future applicationsPoultry industry?
CHITOSAN’S APPLICATIONS
Poultry feed is supplemented with mineral phosphorus Very favorable as a fertilizer for forage But, low N:P ratio relative to forage needs
Storm events dissolve excess P, N, and other nutrients from land applied poultry litter into runoff
In-house and on pasture, ammonia (NH3) volatilization is also an issue, both human health and environmental
Considering these problems, various chemical amendments have been used to decrease water extractable P and N volatilization Decreases P release into runoff during storm events Decreases NH3 volatilization from litter
Processed chitin or chitosan may be able to perform these same functions, even similarly to currently used amendments
POULTRY LITTER: CONTROLLING PHOSPHORUS (P) AND NITROGEN (N)
To evaluate the effects of chitin and chitosan on water solubility of P in poultry litter and N content and volatilization
Hypotheses:1.That chitosan will significantly decrease water extractable P (WEP) in
poultry litter2.That chitin and chitosan have no anticipated effect on NH3 volatilized
from poultry litter3.That chitosan will increase the N content and subsequently the N:P
ratio of poultry litter
Chitin and chitosan’s effects will be compared with those of aluminum sulfate (alum) treated and untreated poultry litter
STUDY GOAL
Three experiments total
Experiment 1: Determine if the provided chitin or chitosan varieties have any
significant effects on WEP content in litter at 1% w/w treatment rate
Experiment 2: Extend the first experiment and determine if chitin or chitosan have
significant effects on WEP content at the extension recommended 5% w/w treatment rate and furthermore, 10% w/w treatment rate
Experiment 3: Determine if chitin or chitosan significantly affects levels of
volatilized NH3 from litter, as well as total N content.
EXPERIMENT OUTLINE
Treatments (1% w/w) Control (1) Alum (ground, 2) Chitin (ground, 3) Chitosan (ground)
Grade C (4)
Grade B (5)
Grade A (6)
Well mixed in 10 g litter samples
Three week incubation at room temperature
WEP measured using ICP-OES and 1:100 extraction ratio (dry litter to water)
EXPERIMENT 1: MATERIALS AND METHODS
Alum treatments had significant decreases in WEP versus control
Chitin treatments were not significantly different from control
Chitosan treatments were not significantly different, and two were not different than alum treatments
Promising results, now try at extension recommendations
EXPERIMENT 1: FIRST RESULTS
TREATMENT
1 2 3 4 5 6
WE
P (
mg
kg
-1 d
ry w
eig
ht)
0
500
1000
1500
2000
2500A C A BC AB BC
TREATMENT
1 2 3 4 5 6
WE
P (
mg
kg
-1 d
ry w
eig
ht)
0
500
1000
1500
2000
2500A C A BC AB BC
Treatments: same amendment options as first experiment
Instead, test at 1%, 5%, and 10% w/w treatment rates based on extension alum recommendations Extension recommendations are between 5-10% w/w
Three week incubation of 5 g samples at room temperature with treatments
ICP-OES and 1:100 extraction ratio used for again WEP and trace element analysis
EXPERIMENT 2: MATERIALS AND METHODS
ControlAlumChitinChitosan
EXPERIMENT 2: 1% RESULTS NOT AS CLEAN
TREATMENT
1 2 3 4 5 6
WE
P (m
g kg
-1 d
ry w
eigh
t)
0
500
1000
1500
2000
2500
3000
3500AB C A BC BC BC
TREATMENT
1 2 3 4 5 6
WE
P (m
g kg
-1 d
ry w
eigh
t)
0
500
1000
1500
2000
2500
3000
3500AB C A BC BC BC
Reduced litter mass used probably increased WEP variability
EXPERIMENT 2: 5% TREATMENTS
TREATMENT
1 2 3 4 5 6
WE
P (
mg
kg
-1 d
ry w
eig
ht)
0
500
1000
1500
2000
2500
3000
3500A B A B B B
TREATMENT
1 2 3 4 5 6
WE
P (
mg
kg
-1 d
ry w
eig
ht)
0
500
1000
1500
2000
2500
3000
3500A B A B B B
ControlAlumChitinChitosan VERY NICE!
EXPERIMENT 2: 10% SHOWED DIVERGENCE AGAINST ALUM
TREATMENT
1 2 3 4 5 6
WE
P (m
g kg
-1 d
ry w
eigh
t)
0
500
1000
1500
2000
2500
3000
3500A C A B B B
TREATMENT
1 2 3 4 5 6
WE
P (m
g kg
-1 d
ry w
eigh
t)
0
500
1000
1500
2000
2500
3000
3500A C A B B B
ControlAlumChitinChitosan
Alum
wins!
Chitosan varieties not
different
Passive diffusion acid traps employed to capture volatilized NH3 from litter
20 g litter samples were placed in Erlenmeyer flasks, only the 5 and 10% w/w rates used
Open, 15mL vials with deionized water pH<2 (concentrated HCl) were place in flasks
Flasks were sealed and allowed to incubate 1 week 2 weeks 8 weeks
Vial solutions were analyzed for NH3-N content Chitin was not used, only chitosan varieties and
alum were used in the incubation
EXPERIMENT 3: MATERIALS AND METHODS
EXPERIMENT 3: NO SURPRISE
Alum showed significant reduction of NH3 volatilization at both rates (5 and 10% w/w)
Chitosan did not influence NH3 volatilization, but it did increase TN content of the litter
Chitosan is usually dissolved in a 0.1 M acetic acid solution or similar
This dissolution may increase its structural ability to remove P from solution
And, application in an acid solution would decrease NH3 volatilization from litter
So, before Iain left for medical school we convinced him that his relationship with manure was not over… One more experiment!
CHITOSAN WAS OBSERVED IN PARTICULATE FORM FOLLOWING
INCUBATIONS.
Chitosan [when mixed with poultry litter] can reduce water extractable P content
Chitosan [alone] does not influence NH3 volatilization, but when delivered via 0.1M acetic acid it does
Chitosan increases the N:P ratio and TN content of poultry litter, but only 0.5% increase in TN content
The optimal treatment is ~5% w/w chitosan, with regard to reduction in water extractable P
Future studies should determine: If chitosan is a cost-effective management option compared to other
alternatives in poultry production How P chelated by chitosan transforms in soils, being that lower WEP
content has been found to control P release into stormwater runoff We also need to look at how pure (i.e., deactylated) chitosan needs to
be to reduce water extractable P in poultry litters
WHAT DO WE KNOW?
THIS STUDY WAS FUNDED BY A STUDENT UNDERGRADUATE RESEARCH
FELLOWSHIP
QUESTIONS?
