AlgalFertilizer project:Algae deliering nutrients from phosphorous-rich media to soil and wheat

As an application-oriented part of the AlgalFertilizer Project, we cultivated Chlorella vulgaris, IPPAS C1 in 3.6 m3 suspension in V-shaped plastic bag photobioreactors (NovaGreen GmbH) in Jülich, Germany. The culture was grown in batch regime in a P-rich medium. The thus produced algal biomass was analyzed for nutrient content with special regard to phosphorus and used as fertilizer to grow wheat in a pot experiment under controlled phosphorus levels on different substrates: sand and nutrient-poor ‘Null-Erde’ for controlled nutrient levels as well as a nutrient-rich substrate (Dachstaudensubstrat, SoMi 513). The algal biomass was mixed into the soil substrates either in form of spray-dried powder or as a suspension of fresh cells obtained by centrifugation to estimate P-exchange properties of pre-treated and fresh biomass. Aiming at comparison to standard Hoagland mineral fertilizer, we applied algae at two different P-levels: high, corresponding to 45 kg(P)/ha and low, corresponding to 4.5 kg(P)/ha. 150 pots were prepared for the experiment. Each experimental variant was represented by 10 pots of identical substrate and fertilization treatment. One pre-germinated seed of wheat (Triticum aestivum, var. Scirocco) was placed in each pot. The plants were placed in a greenhouse on a robotic platform that randomized position of individual pots and also ensured uniform watering. Individual plants were moved regularly with their pots into an imaging system that served to quantify the plant growth. We also analyzed the dynamics of nutrients in the soil. The results of the AlgalFertilizer experiment lead us to conclude that microalgae are not only very potent in sequestering phosphorus from nutrient rich streams (Part 1 of this presentation) but that algal biomass can be used as a very effective fertilizer and ameliorant of nutrient-poor soils (Part 2 of this presentation)