Ryegrass Productivity and Nutrient Availability in Soils Amended With Lipid Extracted Algae.

As an energy source, extracted algal oil presents multiple possibilities for fuel products, such as biodiesel, ethanol, methane, jet fuel, and biocrude. Algae biofuel production would become more sustainable with high revenue end products derived from lipid extracted algae meal (LEA). One possible added value agricultural coproduct is as an organic fertilizer and soil conditioner. The primary objectives of this study were to determine the nutrient availability of LEA in Parrita sandy clay loam soil as well as the potential effects of algae meal on soil salinity and the growth of a salt tolerant Ryegrass (Lolium multiflorum). A glasshouse study was conducted using soil treatments, including a positive control [(soil plus chemical grade, inorganic nitrogen (N) and phosphorus (P)], a negative control with no nutrient additions, 1.5% LEA, 3% LEA, 1.5% wheat straw (WS) residue and 1.5% organic material (OM) of 0.75% WS plus 0.75% LEA. The soil was amended with these treatments and added to the top 15 cm of a 30 cm pvc column, which contained unamended soil in the lower portion. After incubating for 10 d with the soil water content maintained at 60% water filled pore space, the columns were seeded with Ryegrass at 20 seed per column. Seedling emergence and plant growth were monitored initially and throughout the duration of the study (~ 95 d), respectively. Ryegrass plants were harvested a total of three times to a height of 9 cm above the soil surface as to enable a re-growth. Above ground biomass was collected at each of the three harvests and then dried, weighed, and analyzed for total minerals. After the final harvest, soil was sampled from the 0-15 and 16-30 cm depth and analyzed for total carbon (C) and N, extractable macro- and micronutrients, pH and electrical conductivity (EC). The discussion will focus primarily on significant differences of nutrient availability, soil salinity, and aboveground biomass production as affected by LEA soil amendments and other study treatments.