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.

1. Brian E. Haggard
Iain 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?

2. 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?

3. 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.

4. 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?

5. Current applications
Commercial wastewater
treatment
Manure separation
Algae flocculation in
eutrophic waters
Algae immobilization for
nutrient removal
Future applications
Poultry industry?
CHITOSAN’S APPLICATIONS

6.  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)

7. 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 litter
2. That chitin and chitosan have no anticipated effect on NH3 volatilized from poultry
litter
3. 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

8. 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

9.  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

10. 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
WEP(mgkg
-1
dryweight)
0
500
1000
1500
2000
2500
A C A BC AB BC

11. 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

12. Control
Alum
Chitin
Chitosan
EXPERIMENT 2: 1% RESULTS NOT AS CLEAN
TREATMENT
1 2 3 4 5 6
WEP(mgkg
-1
dryweight)
0
500
1000
1500
2000
2500
3000
3500
AB C A BC BC BC
Reduced litter mass used probably increased WEP variability

13. EXPERIMENT 2: 5% TREATMENTS
TREATMENT
1 2 3 4 5 6
WEP(mgkg
-1
dryweight)
0
500
1000
1500
2000
2500
3000
3500
A B A B B BControl
Alum
Chitin
Chitosan
VERY NICE!

14. EXPERIMENT 2: 10% SHOWED DIVERGENCE
AGAINST ALUM
TREATMENT
1 2 3 4 5 6
WEP(mgkg
-1
dryweight)
0
500
1000
1500
2000
2500
3000
3500
A C A B B BControl
Alum
Chitin
Chitosan
Alum
wins!
Chitosan varieties
not different

15.  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

16. 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

17. 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.

18.  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?

19. THIS STUDY WAS FUNDED BY A STUDENT
UNDERGRADUATE RESEARCH FELLOWSHIP
QUESTIONS?