Greenhouse Gas Fluxes As Affected By Lipid Extracted Algae Application to Soil.

Lipid extracted algae (LEA), a nutrient rich end-product of algal biofuel production used as an organic fertilizer and soil conditioner may possibly enhance soil physical and chemical properties, as well as be a potential sink for carbon. Determining the flux of greenhouse gases of carbon dioxide (CO₂), nitrous oxide (N₂O), methane (CH₄), and ammonia (NH₃) generated from algae application to soil using a fully portable Fourier Transform Infrared (FTIR) multi-gas analyzer and a LI-COR chamber may further explain chemical and biological soil processes plus enable our understanding of impacts that algae applications may have on the soil environment and greenhouse gas budgets. A glasshouse experiment was designed in order to quantify the flux of CO₂, N₂O, CH₄, and NH₃ gas from LEA amended soil. Experimental treatments included a positive control [(soil plus chemical grade inorganic nitrogen (N) and phosphorus (P)], a negative control with no nutrient additions, 1.5% LEA (w/w), 3% LEA (w/w), and 1.5% wheat straw (WS) residue (w/w), and 1.5% organic material (OM) of 0.75% WS plus 0.75% LEA (w/w). Each treatment was mixed with Parrita soil and then added to the top 15 cm of a 30 cm pvc column, which contained unamended soil in the lower portion. An aliquot of deionized water was added to each column in order for the soil to be at 60% water filled pore space. Gas measurements began immediately after treatment initiation and continued on a daily basis for 14 d, after which time measurement frequency was reduced to every 3 d and eventually 7 d for a total of approximately 90 d. Discussion will focus primarily on the significant differences between treatments of flux rates and cumulative emissions for each gas.