Using Seaweed As a Soil Amendment: Effects On Soil Quality and Yield of Sweet Corn (Zea mays L.).

Application of seaweed as a soil fertility management strategy is a traditional practice in many coastal regions, utilizing an inexpensive, abundant, and nutrient-rich resource. As a practice that re-purposes waste materials, diversifies inputs, and relies on coastal resources, seaweed amendment may be an effective and inexpensive means of strengthening and supporting agriculture in coastal agroecosystems. Putatively, seaweed biomass may be a useful amendment for crop production due to provision of primary plant nutrients and micronutrients (e.g. N, P, K, Ca), effects on soil water holding capacity, and promotion of microbial activity, among other plant production benefits, but may be limited by high sulfur, salt, and heavy metal content. To assess the application of the practice in coastal New England, the objectives of this study were to: (1) evaluate the effects of seaweed biomass application on diverse soil physical, biological, and chemical parameters important for agricultural productivity, maintenance of soil quality, and associated conservation of soil resources; and (2) assess the sweet corn (Zea mays L. var. rugosa) yield obtained by implementing seaweed amendment as a soil fertility management practice. Soil physical, chemical, and biological quality analyses were completed using standard protocols and molecular techniques. Low- and high-dose seaweed amendment treatments were compared to a treatment receiving inorganic fertilization in a sweet corn production field experiment, initiated in Oct 2011 and continuing through Nov 2012. Preliminary results indicate that soil pH decreased, and electrical conductivity, soil respiration, and NO₃^- levels increased as a result of seaweed amendment, but the changes may vary in persistence. In contrast, bulk density, infiltration, earthworm abundance, and available water capacity were not initially affected. Further evaluation of crop yield and of changes in soil quality and effects developing over time will continue to explore the feasibility and viability of adopting seaweed use in agriculture.