1. Evaluation of N-stabilizers in Enhancing NUE of Animal Manures
Syam Dodla
Red River Research Station
LSU AgCenter
Bossier City, LA

2. Importance US animal industry generates > $100 B
Environmentally safe disposal of their wastes is a challenge
Poultry industry generates >44 million tons of poultry litter (PL) per year
Application to pastures as nutrient source: Most common
Also used as nutrient source in row crop production

3. Poultry Litter as a Nutrient Source:
Approximate Content
Unit N
2 to 4 % P
2 to 3 K
2.5 to 3.5 Ca S
0.5 Zn
500
mg kg-1 Cu
350 Fe
900

4. PL as a Nutrient Source: Limitations
Low nutrient content compared to inorganic fertilizers
Higher transportation costs
Prone to easy losses by leaching, runoff and volatilization
~60 % N expected to be available in year-1
Low N:P ratio
Soil P imbalance and P runoff

5. Strategies to Improve NUE
Inorganic N-fertilizers
Split application
Soil incorporation/ sub-surface application
N-stabilizers (N-stab)
Polymer coating
Animal wastes
Split application X
Polymer coating X
Soil incorporation
N-stabilizers. ??

6. Objectives Evaluate the use of N-stabilizers in enhancing NUE of PL
Evaluate the temperature effect on N-stabilizers in enhancing NUE of PL

7. Study 1: Evaluate the use of N-stabilizers in enhancing NUE of PL

8. Methodology 3-year field experiment Crop: Cotton
Soil: Very fine sandy loam
Treatments:
Control,
PL (equivalent to 90 kg N ha-1)
PL+ 3 kg ha-1 N-stab.,
PL+ 6 kg ha-1 N-stab.
N-stabilizers
Year1: Agrotain DriMaxx (60% NBPT)
Year 2 and 3: Agrotain Plus (6.5 % NBPT + 81% DCD)

9. Passive Chamber Method
Methodology
Monitoring parameters:
NH3 emissions: Active chamber method
N2O emissions: Passive chamber method
Tissue nutrient content
Seed cotton yield
Active Chamber Method
Passive Chamber Method

10. Results

11. Tissue N-content Treatment Tissue N Content (%) 2014 2015 2016 Control
3.40
3.67
3.09 PL
3.80
3.39
PL+ 3 kg ha-1 Agrotain
3.91
3.90
3.31
PL+ 6 kg ha-1 Agrotain
3.72
3.89
3.46

12. NH3 Emissions

13. N2O Emissions

14. Seed Cotton Yield Treatment Seed Cotton Yield 2014 2015 2016 Control -
2709
2229 PL
1650
2955
2871
PL+ 3 kg ha-1 Agrotain
1862
2931
2882
PL+ 6 kg ha-1 Agrotain
1853
3144
3031

15. Summary
N-stabilizers useful to enhance NUE of poultry litter potentially all animal wastes
NBPT may be more effective to improve NUE over DCD
N loss as NH3 is much higher than N2O
For animal wastes, application rate should be on area based rather than N content

16. Study-2 Temperature Effect on N-stabilizers in Enhancing NUE of Poultry Litter

17. Methodology Laboratory Incubation: 500 g silt loam soil
4.2 g of PL/ jar (or 180 kg N ha-1)
Incorporated into top soil
Moisture at 60 % of Field capacity
Treatments:
Main treatments: Temperature 23 and 30oC
Sub Treatments: Different N-stabilizers
Control, NBPT, DCD, K32
Continuously flushed with NH3 free air
Trapped outgoing air in H3PO4 solution for NH3
Analyzed for NH3 using Lachat

18. Effect of Temperature on NH3 Emissions
Temperature significantly effects the NH3 emissions
N-stabilizer found to be minimize NH3 emissions only at higher temperature, while no significant impact at low temperatures

19. Acknowledgements
Funding: Louisiana Board of Regents and Koch Industries
Research Associates: Hari Bohara and Dr. Nutifafa Adotey
Collaborators: Drs. Dustin Harrell, Manoch Kongchum and Jim Wang

20. Questions?