Effect of Organic Nitrogen Fertilizer Source, Application Method, and Application Rate on Ammonia Volatilization from Drip Irrigated Lettuce.

ABSTRACT

Ammonia (NH₃) volatilization is an important issue with both agricultural and environmental aspects. The objective of this study was to evaluate the impacts of fertilizer source, application method, and rate on NH₃ volatilization. The fertilizers tested included solid fertilizers (blood meal and feather meal) and liquid fertilizers (fish emulsion and cyano-fertilizer). The study was conducted at Colorado State University's Horticulture Field Research Center, Fort Collins, CO. 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. Solid fertilizers were applied all at once before transplanting, while liquid fertilizers were applied weekly beginning two weeks after transplanting. Semi-open static chambers were used to measure NH₃ volatilization, samples were extracted using 2M KCl and analyzed using DIN # 38406 method. Using a Randomized Complete Block Design (RCBD) with four replications in SAS, the results indicate that there was a significant difference among the different treatments. On the other hand, there was no difference between application rates. Furthermore, the Tukey-Kramer test specified which treatments were different from each other. Feather meal applied at both rates and blood meal applied at 56 kg N ha^-1 had significantly higher NH₃ emissions than cyano-fertilizer and fish emulsion applied at either rate. Moreover, the Dunnet's test indicated significant differences between control and blood meal at 56 kg N ha^-1 (P = 0.0034), feather meal at 28 kg N ha^-1 (P = 0.0202), and feather meal at 56 kg N ha^-1 (P = 0.0059). Blood meal at 56 kg N ha^-1 and feather meal at both rates had the highest NH₃ volatilization rates compared with other treatments. No previous studies have evaluated NH₃ volatilization from these organic fertilizers; therefore, a follow up study is required to confirm these results.