Circular economy fertilization: Testing micro and macro algal species as soil improvers and nutrient sources for crop production in greenhouse and field conditions

• Published in: Geoderma Vol. 334; pp. 113 - 123
• Main Authors: Alobwede, Emanga, Leake, Jonathan R., Pandhal, Jagroop
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.01.2019
• Subjects: agricultural land; Agricultural soil; agricultural soils; Algae; algal blooms; ammonium; application rate; arable soils; Arthrospira platensis; Ascophyllum nodosum; biomass; Chlorella; Circular economy; elemental composition; eutrophication; field experimentation; freshwater; grain yield; greenhouse production; greenhouses; Laminaria digitata; macroalgae; marine environment; nitrates; nitrogen; nitrogen content; nutrition; Palmaria palmata; phosphorus; physicochemical properties; plant growth; Plant nutrition; recycling; Soil nutrient status; soil quality; Spirulina; spring wheat; Yield; Agricultural soil; Yield; Circular economy; Soil nutrient status; Plant nutrition; Algae
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2018.07.049

Nutrient losses from agricultural land to freshwater and marine environments contribute to eutrophication and often to the growth of algal blooms. However, the potential benefits of recycling this algal biomass back to agricultural land for soil quality and crop nutrition in a “circular-economy” has received little attention. We tested the effects of algal additions to arable soil in greenhouse-grown garden peas, and field plots of spring wheat, on plant growth and nutrition and physical and chemical properties of the soil. Representatives of five algal species, which contrasted in elemental composition, were applied at 0.2, 2 and 4 g kg−1 in the greenhouse and at 24 g m2 in the field. These included the cyanobacteria Arthrospira platensis (Spirulina), the unicellular green algae Chlorella sp., the red seaweed Palmaria palmata, and the brown seaweeds Laminaria digitata and Ascophyllum nodosum. In the greenhouse at the highest application rates (4 g kg−1), Chlorella sp., and Spirulina increased soil total nitrogen and available phosphorus, and Spirulina also increased soil nitrate concentrations. P. palmata and L. digitata significantly increased soil inorganic (NH4+ and NO3−) concentrations under all three application rates. Chlorella sp. significantly increased soil total P, N and C, available P, NH4+-N, and pea yield. Soil water-stable aggregates were unchanged by the algal additions in both the greenhouse and field study. In the field, 4 species (Chlorella sp. Spirulina, P. palmata and L. digitata) increased soil inorganic nitrogen concentrations, confirming their potential to recycle mineralizable nitrogen to agricultural soils, but no significant effects were found on wheat yields under the application rates tested. •Recycling algal biomass has shown improvements to soil chemical properties.•Four chemically different algal species improved soil available nitrogen.•Chlorella sp. increased soil nutrient concentrations as well as crop yields.