|May 10, 2004: Seaweed
is a rich source of trace minerals, vitamins and plant hormones that
has been widely used by organic farmers to promote crop growth; yet,
many farmers are not fully aware of this resource and its potential
benefits on their farms.
Researchers in New Zealand tested soil, foliar, and combined soil
plus foliar applications of seaweed for their effects on kiwifruit
growth. Organic-research.com recently published a full report of
this thee-year analysis of seaweed impact on kiwifruit production
(Perham, J. 2003. Ocean Brew Seaweed Kiwi Efficacy Trials.
Seaweed applications increased kiwifruit firmness and storage life
while reducing fruit rot up to 50 percent. Positive effects on fruit
quality were found from both soil and foliar applications and the
combined applications added to the benefits. The kiwi vines killed
by wind were reduced by 44 percent when using the combined seaweed
applications. The fruit calcium level was increased by seaweed about
10 percent while fruit nitrogen was about 20 percent less than the
These changes in nutrient composition were associated with reduced
kiwifruit pitting. Fruit pitting in kiwi is a physiological disease
associated with low calcium and high nitrogen levels.
Fruit weight when seaweed was used increased up to 11 percent,
but the number of 22 count marketable fruit increased a whopping
Many seaweed providers are using sustainable harvest techniques
to ensure the long-term viability of this wild natural resource.
Foliar application is a technique that can result in great benefits
from often relatively small natural inputs.
The New Zealand kiwifruit results illustrate how small foliar applications
applied as tonics can have large impacts on crop quality and growth
in some environments. Besides the direct impact on kiwifruit production,
seaweed applied to soil increased earthworm numbers up to 150 percent
over the control, indicating positive environmental impact.
Dr. Paul Hepperly is New Farm Research & Training Manager
at The Rodale Institute. He grew up on a farm in northwestern Illinois
and has 30 years of research experience in tropical and temperate