Evaluating Carbon Dioxide, Methane, and Nitrous Oxide Flux from N- and P-Based Broiler Litter Fertilization of Bermudagrass

Escalating costs of commercial fertilizers have resulted in a renewed interest in the use of broiler litter and other manure nutrient sources for crops and forages. In recent years, research has been conducted using different application rates of broiler litter, particularly nitrogen (N) based or phosphorus (P) based. Applying litter based on plant N needs can result in an overabundance of P that may be subject to runoff. The current study addresses not only soil and water nutrient dynamics (presented elsewhere), but assessed carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) flux from bermudagrass plots receiving N- and P-based broiler litter application. Using a photoacoustic multigas analyzer and an inverted flux box, CO₂, CH₄, and N₂O flux were assessed prior to application (background), at litter application, and after 3, 18, and 24 hours (h). With this method, background fluxes were estimated at 1493 mg m^-2 hr^-1 CO₂, 94.4 mg m^-2 hr^-1 CH₄, and 0.39 mg m^-2 hr^-1 N₂O. Carbon dioxide and CH₄ showed an initial increase at the time of application, a decrease at 3 and 18 h, then increased again at 24 h. However, the decrease for CO₂ was slight, remaining above the background flux, but the CH₄ dropped well below the background level to approximately 5 mg m^-2 hr^-1 at 18 h. Nitrous oxide demonstrated an increase through 3 h, and then leveled off to 1.09 - 2.36 mg m^-2 hr^-1. Only the CO₂ showed a difference based on application rate at 24 h, where the CO₂ flux for the N-based fertilizer rate was greatest at 2234 mg m^-2 hr^-1. The study demonstrates that these gas fluxes vary with time after litter application and follow dissimilar trends, thus complicating comprehensive strategies for sustaining water, land, and air resources.