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UBC Theses and Dissertations

The use of the kelp, Macrocystis integrifolia, as a soil amendment and foliar spray upon selected crops Temple, Wayne Douglas


In this investigation the coastal B.C. kelp, Macrocystis integrifolia, was evaluated for its potential use as a soil amendment and foliar spray in crop production. The kelp soil amendment was applied fresh to a fine-textured deltaic soil with applications of 0, 7.5, 15, 30, 60 and 120 t ha⁻¹. Soil chemical, physical, crop growth and nutritional responses were characterized over a two year period. Beans (Phaseolus vulgaris) were planted in the first year and peas (Pisum sativum) were planted in the second year. Plant growth responses included reduced yields, emergence and flowering with the 120 t ha⁻¹ application and increased plant moisture content with increasing kelp applications. Nutritional responses included increased plant elemental concentrations and uptakes of Na, K and Cl with increasing soil applications of kelp. Soil responses to increasing applications of kelp included sharp increases in soil water-soluble salts, Cl , NO₃-N, exchangeable K and Na, and a decline in soil pH. Subsequent greenhouse experiments suggested that phytotoxic effects from the 120 t ha⁻¹ kelp applications were primarily induced by high levels of soluble salts, but an unknown phytotoxic substance may be implicated. Soil aeration increased with kelp application up to 60 t ha⁻¹, but declined with the 120 t ha⁻¹ application. The use of KL inteqrifolia as a processed concentrate for subsequent dilution with water and foliar application (2 and 4 L ha⁻¹) to the bean (P. vulgaris) crop resulted in increased harvestable bean yields in each of two field seasons. Evidence is presented which supports the theory that growth promoting phytohormone-like substances extracted from the kelp may, in part, be active constituents of the kelp concentrate. Field crop nutritional responses to kelp foliar sprays included reduced shoot elemental concentrations, but increased uptakes, suggesting greater dry matter accumulation per unit element. Crop growth and nutritional responses between growing seasons were not consistent. A greenhouse experiment demonstrated that many of the kelp foliar spray effects upon crop growth, development and nutrition could be dependent on soil moisture regimes.

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