Dissertation - Open Access
Doctor of Philosophy (PhD)
Agricultural and Biosystems Engineering
Erin L. Cortus
Manure management, livestock operations, cattle production, bench-scale manure storage experiment
Manure management is of growing concern for beef cattle producers and the general public. The overall objective of this research was to develop a process-based model that predicts concentration and gaseous emission from the bedded manure pack of a confined beef cattle system, with respect to different bedding material, manure storage time, and ambient temperature. The model incorporated the data collected in three experiments designed to understand transformations and processes occurring in the bedded pack. The first study evaluated the source of volatilized ammonia nitrogen from beef cattle manure. Isotope ratio mass spectrometry was used to determine the origin of aerial ammonia nitrogen losses (urine or fecal material) from the relative isotopic abundance of nitrogen in the 15N -labeled slurry mixture. On average 84% of total ammonia nitrogen losses originated from the urine portion and were highest during the first two to four days, when fresh material was added. The second and third experiments were conducted to determine differences in ammonia, carbon dioxide, nitrous oxide, and methane concentrations and moisture content, nutrient concentrations (ammonium nitrogen, total nitrogen, total phosphorus, total potassium), short-term nitrification activity potential, and denitrification enzyme activity from simulated beef cattle bedded manure packs related to storage length (0 to 3, 3 to 6, and 6 to 9 weeks), bedding material (corn stover or soybean stubble), and temperature (10°C or 40°C). Temperature impacted all nutrient concentrations, while most variables differed with age and sample depth. A strong relationship between water and nutrient movement existed. Nitrous oxide concentrations occurred as high pulses right after material addition which was most likely caused by incomplete denitrification from pulse nitrate concentrations available in the dried bedding material. Ammonia concentrations were three times higher above bedded packs at 40°C assumedly because major ammonia losses occur through urea hydrolysis which is temperature-dependent and completed faster at higher temperatures. A model was developed based on the Integrated Farm Systems Model (IFSM). The main process for water movement was considered evaporation. Ammonia emissions were simulated based on the urea degradation process in the urine, while nitrous oxide emissions were predicted as denitrification losses. Compared to data from the bedded pack experiments, the model did not adequately capture observed hourly conditions for ammonia and nitrous oxide conditions which did not affect total nitrogen concentration. Ammonia emission at times of material addition were realistically predicted which is important for real-life barns. Depending on bedded manure pack age, the bias in model prediction for moisture content, nitrogen, phosphorus and potassium concentrations were on average 3%, 20%, 0% and -25% , respectively. Overall, the simulations showed that the model can be used to predict N-P-K fertilizer concentration for bedded manure packs.
Library of Congress Subject Headings
Beef cattle--Feeding and feeds
Includes bibliographical references (pages 178-189)
Number of Pages
South Dakota State University
Copyright © 2015 Ferouz Y. Ayadi
Ayadi, Ferouz Y., "A Process-Based Nutrient Model for the Bedded Manure Pack of Confined Beef Systems" (2015). Electronic Theses and Dissertations. 274.