Ammonia (NH3) volatilization is an important issue with both agricultural and environmental aspects. The hypotheses investigated in this experiment are: i) liquid fertilizers will have lower NH3 emissions compared with solid fertilizers and ii) application methods which place fertilizers below the soil surface will lower NH3 volatilization rates. This study was designed to measure apparent NH3 volatilization from four organic nitrogen (N) fertilizers to evaluate the impacts of fertilizer source, application method, and rate on NH3 volatilization. The fertilizers used in this study were both solid fertilizers (blood meal and feather meal) and liquid fertilizers (fish emulsion and liquid cyano-fertilizer), and control, which received no fertilizer application. The study was conducted at the Colorado State University Horticulture Field Research Center, Fort Collins, CO in 2014 and 2015. In 2014, two application rates (28 and 56 kg N ha-1) were applied to an organic lettuce (Lactuca sativa) crop to evaluate the effect of rate on NH3 loss. In 2015, the crop used was cucumber (Cucumis sativus), and solid fertilizers were applied using two methods, sub-surface banded and surface banded. In addition, all fertilizers were applied at 28 kg N ha -1 in 2015. The NH3 volatilization measurements on solid fertilizer treatments were taken daily for the first seven days, and after that the measurements were taken every three days until liquid fertilizer application began; then measurements were taken on the third and seventh day of each week. In contrast, NH3 volatilization measurements from liquid fertilizer treatments were made 1, 3, and 7 days after each application. Moreover, cucumber measurements of length, diameter, weight, fruit number, and plant dry weight were taken to evaluate the effect of the fertilizer treatments on yield. Semi-open static chambers were used to measure NH3 volatilization. After collecting the samples from the field, samples were extracted using 2M KCl and analyzed using DIN method # 38406. Using a Randomized Complete Block Design (RCBD) with four replications in SAS, the 2014 results indicated that there was a significant difference in apparent NH3 volatilization among the fertilizer treatments. On the other hand, there was no difference between the application rates. Furthermore, the Tukey-Kramer test specified which treatments were different from each other. Feather meal had greater apparent NH3 volatilization than cyano-fertilizer and fish emulsion. Blood meal applied at 56 kg N ha-1 had significantly more NH 3 loss than cyano-fertilizer and fish emulsion. In addition, NH 3 flux from feather meal at both application rates and blood meal applied at 56 kg N ha-1 were also higher than the control with 0.05 mg/cm2 mean flux (by Dunnet's test), but cyano-fertilizer and fish emulsion had NH3 fluxes similar to the control. Among the four fertilizers, blood meal at 56 kg N ha-1 with a 0.09 mg/cm2 mean flux and feather meal at both rates with 0.08 and 0.09 mg/cm2 mean flux had the highest NH3 volatilization rates compared with other treatments. In 2015, the overall test indicated that there was a significant difference in apparent NH3 volatilization among the fertilizer treatments. The Tukey-Kramer test showed that surface banded blood meal with a 0.07 mg/cm2 mean flux and feather meal with 0.09 mg/cm2 mean flux had higher NH3 emissions than cyano-fertilizer, fish emulsion, and sub-surface banded blood and feather meals. Furthermore, sub-surface banded blood meal, sub-surface banded feather meal, cyano-fertilizer, and fish emulsion were not different from control with 0.04 mg/cm2 mean flux. Volatilization from solid fertilizers did not occur immediately and usually peaked within 14 d, while liquid fertilizers had peak volatilization rates immediately following fertigation and declined thereafter. Application methods that involved burying the fertilizers under the soil surface or applying liquid fertilizers through drip irrigation had less apparent NH3 volatilization. All fertilizer treatments had similar cucumber fruit number in the first harvest, but in the second harvest, surface banded blood meal had the highest fruit number. Sub-surface banded blood meal had the highest cucumber yield in the first harvest, while all fertilizers had similar yield in the second harvest. In addition, there was no significant difference in plant dry weights among fertilizer treatments. Fish emulsion had the lowest cucumber yield compared to the other fertilizers. (Abstract shortened by ProQuest.).