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

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

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

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

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. ??

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

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

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)

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

Results

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

NH3 Emissions

N2O Emissions

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

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

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

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

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

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

Questions?