Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Agricultural and Biosystems Engineering

First Advisor

Hongwei Xin


Ammonia (NH3) emission is environmentally important because of its contribution to acidification of soil and water and increased nitrogen deposition in ecosystems. Ammonia emission rates (ER) of two commercial manure-belt (MB) layer houses with in Iowa were monitored for a full year. Ammonia ER showed considerable diurnal variation, but not as much in seasonal variation. Data from the 12-month monitoring revealed an annual average NH3 ER of 0.054 g d-1 hen-1(varying from 0.002 to 0.195 g d-1 hen-1) from the MB houses when the manure was removed daily. Results of the study contribute to the U.S. national inventory on NH3 emissions from animal feeding operations;While manure removal via manure belt system is effective in improving indoor air quality and reducing house-level emissions, manure transferred into storage facility also emits NH3 and needs to be quantified. The effects of moisture content of the manure, ambient temperature, surface to volume ratio (SVR) of manure stack, air exchange rate, and duration of the manure storage on NH3 emission were quantified. Rising ambient temperature enhances NH3 emission of the manure stack at the rate of 6% per degree Celsius rise for the temperature range of 21 to 32°C. The NH3 emission rate (ER) from manure stack at 50% moisture content (MC) is 59% of the NH3 ER from manure stack at 77% MC. A regression model was developed to describe the NH3 emissions from manure stack with five SVRs and storage time. Reducing emissions from manure storage is of practical significance to the improved environmental stewardship. Four topically applied chemical additives (zeolite, alum, Ferix-3 and PLT) were tested to evaluate the efficiency on NH3 emission reduction from stored laying hen manure. The results provide the base line NH3 emission data from poultry manure storage and potential solutions to mitigate NH3 emission;In addition, indirect CO2 balance method and direct ventilation rate measurement method using a Fan Assessment Numeration System were compared in a commercial manure-belt laying hen house. The results showed that careful application of the indirect method could greatly improve the affordability and versatility of endeavors toward quantifying air emissions from confined animal housing.



Digital Repository @ Iowa State University,

Copyright Owner

Hong Li



Proquest ID


File Format


File Size

124 pages