Session: Production, Management, and Environment II

285 - Effects of Encapsulated Calcium-ammonium Nitrate on Greenhouse Gas Emissions from Manure of Beef Steers Grazing a Mature Mixed-winter Forage

Friday, July 16, 2021

2:45 PM – 3:00 PM EST

Location: Kentucky International Convention Center (KICC), L007/008

Author(s)

DH

Darren D. Henry, n/a

Assistant Professor
Texas Tech University
Lubbock, Texas

Presenting Author(s)

Andrea M. Osorio Doblado, MA

Research Assistant
Texas Tech University
Lubbock, Texas

PDF Slides and Audio

Author(s)

Sebastian E. Mejia-Turcios, MSc

Graduate Student
UC Davis
Davis, California
DV

David A. Vargas

Texas Tech University
Lubbock, Texas
LS

Lindsey C. Slaughter

Texas Tech Univeristy
Lubbock, Texas
MK

Marta Kohmann

Univeristy of Florida
Ona, Florida
FC

Francine M. Ciriaco, n/a

Post Research Associate
Texas Tech University
Lubbock, Texas
JO

Jhones Onorino Sarturi, n/a

Associate Professor
Texas Tech University
Lubbock, Texas
ND

Nicolas DiLorenzo

UF - NFREC
Marianna, Florida

A 30-d experiment was conducted to evaluate daily and cumulative gas fluxes of N₂O, CH₄, and CO₂produced by manure from Angus-crossbred steers grazing mature mixed-winter forage pastures [wheat, triticale, and rye (Triticum aestivum, Triticosecale rimpaui, and Secale cereal, respectively) and receiving N supplementation from two different sources. Steers received the following treatments: 1) mature mixed-winter pasture + ground corn (NCTRL), 2) NCTRL + 328 mg/kg of BW encapsulated calcium-ammonium nitrate (NIT) and 3) NCTRL + 124 mg/kg of BW urea (CTRL). All ground corn was supplemented at 0.3% BW. Treatments NIT and CTRL were isonitrogenous. Feces were collected and composited (1 kg as-is) within treatment, within block (3 blocks; 4 steers/treatment/block; 3 fecal composites/treatment). Gas samples were collected from static chambers previously installed in an area excluded from grazing. After 3 d, composites were deposited on the soil surface inside the chamber. Four subsamples were taken per deployment time per chamber, separated by 10-min intervals (t₀, t₁₀, t₂₀ and t₃₀) and injected into an evacuated 125-mL serum vial. Gas samples were collected every other day between 0900 and 1100 h and analyzed using a gas chromatograph. Data were analyzed as a randomized complete block design, with chamber as the experimental unit, using the MIXED procedure of SAS. No treatment × day interaction (P ≥ 0.145), nor treatment (P ≥ 0.622) effect were observed on daily-flux data for N₂O, CH₄, and CO_2;however, a day effect was observed (P ≤ 0.001) where all gases peaked on d 2 post-manure application on the soil. Cumulative emissions were not different among treatments for N₂O, CH₄, and CO₂(P ≥ 0.663). Although it was expected for encapsulated calcium-ammonium nitrate to increase N₂O emissions, such effect was not observed. Therefore, it appears that encapsulated calcium-ammonium nitrate does not affect manure greenhouse gas emissions.