Quick tests for the determination of ammonia in poultry litter

AMBL, ARS, USDA, Beltsville, Maryland 20705, USA. jreeves@anri.barc.usda.gov

The objective of this work was to test the ability of various available quick tests to determine ammonia concentration of poultry litters. A total of 136 samples was collected from brood chambers of poultry houses. Samples were equally divided between surface samples (top 25 mm) and core samples. Samples were frozen until analysis but received no further processing. Samples were analyzed for ammonia by autoanalyzer (standard) and several quick tests (conductivity, Quantofix N-Volumeter, and Reflectoquant). In addition, samples were analyzed by near-infrared spectroscopy by scanning samples using a large-sample transport device on a FOSS-NIRSystems model 6500 (64 co-added scans from 400 to 2,498 nm). Results showed that, although ammonia could be determined with reasonable accuracy by near-infrared spectroscopy using data in the 1,100 to 2,498 nm spectral range (final calibration R2 of approximately 0.90), none of the quick tests, including near-infrared, worked as well as previously found with dairy manures. The best results were found using the Quantofix or Reflectoquant (R2 of approximately 0.75), and conductivity worked only with the core samples (R2 of approximately 0.75). It is believed that interferences due to the presence of uric acid (spectroscopy, Quantofix, and Reflectoquant) and sodium bisulfate used to treat the litter (conductivity) were the cause of the decreased accuracies as compared to results achieved previously with dairy manures.