Sea shells to help sick pine trees

11 08 2010

Sea shells to make soil fertilizers for sick trees

From the Daily Yomiuri Online (h/t Ralph):

Scallop shells may help save pine trees

The Yomiuri Shimbun

A fishing town in northeastern Miyagi Prefecture has turned to the lowly scallop to save its pine trees from a weevil blight.

Minami-Sanrikucho is experimentally grinding the shells of scallops, the town’s speciality, into nutrient-rich powdered fertilizer that it hopes will make the pines resistant to weevils.

The town has about 1,924 hectares of pine woods, but since around 1970 weevils have been badly damaging the trees, mainly in a coastal area of the town. About 20,000 damaged trees have been cut down.

Local residents fear not only that the blight may ruin one of the town’s scenic attractions, but that loss of the trees may result in landslides. Pine trees also absorb carbon dioxide, thus helping reduce global warming.

Since the blight began, the town office has spent about 10 million yen a year on such measures as spraying pesticide and cutting down withered trees, to little effect.

A town official heard that another municipality suffering from the same problem had found it effective to spread oyster shells as fertilizer on the soil in pine woods. Calcium and minerals contained in the shells promoted growth of the trees and made them strong enough to withstand the weevils.

Scallops are farmed in Minami-Sanrikucho, producing from three to five tons of shells that are thrown out every day. A marine products processing company in the town developed a technology to grind the shells into powder.

As powder made from scallop shells is finer than that from oyster shells, it can more easily permeate soil. Also, as the powder contains strongly alkaline calcium, it is expected to more effectively protect pine trees against the weevils.

On July 7, the town started the experiment using the new fertilizer. Town officials and local residents spread a total of 60 kilograms of the fertilizer around 22 dying red pine trees that are 57 years old. The town will check the condition of these trees every three months and spend two years monitoring the fertilizer’s effectiveness.

“I hope the pine woods will be revived and help curb global warming,” a 74-year-old resident in the town who helped spread the fertilizer said.

(Aug. 11, 2010)



5 responses

18 11 2010
Tree Survey

Great post thank you, very interesting to consider that everything has a counterbalance in this world.

6 08 2011

Don’t know if you will read this or have time to answer, but are eggshells a decent substitute?



6 08 2011
Lee Klinger

Eggs shells should work, but you will need a lot of them. For a typical mature pine I’m applying 50 lbs. or more of oyster shell flour (calcium source), plus and equal amount of Azomite (trace mineral source).

3 12 2016
Robert Diamond

I found a large sea shell at the base of a 140 year old Austrian Pine tree that when we excavated the stump to plant another tree. The tree had succumbed to a blight over time. We live in S.E. Wisconsin and our home was built in 1878. Was this a common practice back then? The tree may even predate the property and was close to an Indian trail.

3 12 2016
Lee Klinger

Difficult to know how common the use of shells was in your area a century or more in the past. I am aware of reports that early settlers in some areas of the midwest dug up shell middens for use as fertilizer in their fields. Also, see:

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