Nitrate and Overuse of Organic Fertilizer S1
Sohn, S. M.
Faculty of Plant Resources, Dan Kook University, 330-714 Cheon An, Republic of Korea
|The overuse of organic fertilizer by some
organic farmer have caused some severe problems since they apply too much organic
fertilizer compared to the need of crops. Investigation showed high NO3- accumulation in
vegetables grown by organic fertilizer such as Chinese cabbage (1-6 ppm) and kale (1.5-9
ppm) in Korea, and root (2.5-5 ppm) and leaf (2.5-9 ppm) of kabu in Japan, respectively.
But in the case of Chinese cabbage, lettuce and radish, the NO3- contents do not increase
over 1.5-2 ppm if organic fertilizer is applied in amounts just sufficient to cover the
needs of the crops. And NO3- accumulation in rhizosphere of Chinese cabbage, lettuce and
radish, if applied too much organic fertilizer over the long-terms period, showed the
potential risk for NO3- leaching under Korean climate, soil and crop system. There is
still no basic standard for organic agriculture in Korea and Japan. Organic farmers in
this regions do not follow the minimum requirements of IFOAM basic standard. Most of them
just practice the organic agriculture applying organic fertilizer, commercial seed even
glasshouse care without legume, rotation and green manure. But they believe this system is
a absolutely environmental friendly agricultural system and it produce a safe agricultural
product since they are not aware of the basic standard of organic agriculture at all.
It is recommended that organic farmer have to apply an appropriate rate of organic fertilizer by soil testing to avoid NO3- accumulation in the edible part of vegetables and in rhizosphere. To Korea and Japan, it is also necessary to introduce immediately the basic standard of organic agriculture; the standards which coincides with IFOAM's.
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