Do seaweed extracts improve vegetable production?

Abstract

Seaweed and seaweed extracts have been reported to improve seed germination, crop yield, disease resistance, frost hardiness, etc. This study evaluated the germination of pea and sweet corn seeds and the growth of five vegetables treated with seaweed extracts in experimental field plots. Commercial seaweed extracts (Maxicrop and Micro-Mist 300) and developmental kelp extracts (produced by ASL.) were tested for their effect on emergence and growth of various vegetable crops. At temperatures 18°C or below, both the Micro-Mist 300 and kelp extracts accelerated germination; however, when soil temperatures exceeded 18°C, none of the extracts positively influenced germination. Field experiments with beans, potatoes, cabbage, sweet corn and cucumbers were conducted in loamy sand and sandy loam soils near Truro, N.S. Treatments consisted of control, Micro-Mist 300, gypsum and as many as three rates of the developmental kelp extract. Micro-Mist 300 and kelp extracts were sprayed on the crop foliage at the rate and time recommended for the products. All treatments received N-P-K fertilizer according to the soil test recommendations for the particular vegetable. None of the seaweed amendments improved crop yield over the control; in fact, there were slight reductions in yields using the higher rates of kelp extract. Additionally, there were no significant differences in the elemental tissue composition of sweet corn and cabbage leaves, the two crops for which tissue analyses were conducted. We concluded that none of the seaweed or kelp extracts improved the growth of any of the vegetables tested.