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Advisor(s)
Abstract(s)
Producing microalgae with agricultural drainage water (ADW) allows recycling water and nutrients, with the produc-
tion of a biofertilizer, avoiding receiving waters' contamination. Chlorella vulgaris and Scenedesmus obliquus were culti-
vated using ADW and standard media supplementation and presented higher productivities, relatively to the control
industrial growth medium (using freshwater). Selected strains were grown outdoors in pilot flat panel
photobioreactors, reaching 2.20 g L−1 for S. obliquus and 1.15 g L−1 for C. vulgaris, and degrading herbicides in the
ADW to non-quantifiable concentrations. The potential of the C. vulgaris and S. obliquus suspensions to replace 50%
of nitrogen (N) mineral fertilization of lettuce (0.5 g pot−1) was evaluated through a pot trial, also using a 2-times
(1.0 g pot−1) and 5-times (2.5 g pot−1) higher dose, applied 31 days before lettuce transplanting. Even the lower
dose of N, applied via C. vulgaris or S. obliquus suspensions, was able to provide significantly higher lettuce fresh matter
yield, relatively to the mineral fertilized control. Soil enzymatic activities were improved, with significantly higher de-
hydrogenase, β-glucosidase, and acid phosphatase activities for the 2.5 g pot−1 dose, more marked for S. obliquus,
which was also able to increase soil organic matter content. Both the non-fertilized control and microalgae fertilized
pots led to similar soil electrical conductivities, 3-fold lower than in the N-mineral fertilized pots, evidencing the capac-
ity of microalgae fertilizers to avoid soil secondary salinization. Results suggest benefits from using ADW from maize
cultivation to produce C. vulgaris or S. obliquus suspensions, that can be further used as liquid organic slow-release
fertilizer.
Description
Keywords
subsurface agricultural drainage microalgae herbicides nutrients lettuce (lactuca sativa) organic slow-release fertilizer
Pedagogical Context
Citation
Alvarenga P., Martins M., Ribeiro H., Mota, M., Guerra, I., Cardoso H., Silva, J.L. (2023). Evaluation of the fertilizer potential of Chlorella vulgaris and Scenedesmus obliquus grown in agricultural drainage water from maize fields. Science of The Total Environment: 861,160670
Publisher
Elsevier