• Chunichi Shimbun


The habitat of the Japanese crested ibis, one of the nation’s special natural treasures, is improving on Sado Island thanks to new technology for cleaning contact lenses.

To let the birds feed on water creatures, farmers on the island in Niigata Prefecture have been leaving their rice fields submerged even during winter. However, this means they cannot clear out leftover rice straw, which subsequently interferes with rice cultivation.

To address this problem, Nagoya-based contact lens maker Menicon Co. used its stain removal technology to create a substance to accelerate the decomposition of rice straw. Since the substance can simply be sprinkled on rice fields, it encourages more farmers to leave them flooded after harvest.

This in turn has helped revive the wild population of the crested ibis, which had been extinct outside of captivity for decades. More than 300 of the birds now live on the island together with Sado’s residents.

Menicon has devoted many years to researching an enzyme that can break down and remove stains that adhere to contact lenses. During its research, the firm discovered an enzyme that can cut through plant fiber such as rice straw and commercialized it as an agricultural material in 2003.

“At first, we marketed it as an alternative to burning rice fields, which is how farmers typically dispose of rice straw after harvest,” said 54-year-old Yutaka Matano, the chief researcher at Menicon who developed the product.

On Sado, however, they found a different purpose for it.

In an effort to restore the bird’s habitat, farmers recently adopted the practice of reflooding their rice fields each November after the annual harvest.

This helps loaches and other creatures survive the winter, thereby providing food for the ibis. But the leftover rice straw cannot be decomposed by microorganisms and is left underwater to rot at the bottom of the fields, inhibiting the growth of seeds for the following year’s harvest.

Upon learning of the problem, Menicon suggested sprinkling its decomposition accelerator on the fields to help farmers who were keeping their paddies flooded.

The firm claimed that one sprinkling is enough to produce results. The powder costs about ¥3,000 per 2-kg bag.

According to a local agricultural cooperative, about 4,000 bags were sold in 2017, up from 150 in 2006 when they first went on sale. A quarter of the bags were used to treat the reflooded rice paddies.

“Because it can reduce the impact on the following year’s harvest, I think it gives farmers peace of mind,” a cooperative official said.

In the past decade, the area covered by paddies flooded during winter has expanded by 300 hectares to roughly 675 hectares.

“It’s an honor to be able to contribute to improving the habitat of the crested ibis,” said Matano, the Menicon researcher, who happens to be from Niigata.

Menicon has been applying its lens cleaning know-how to agriculture since the 2000s.

This section, appearing Tuesdays, features topics and issues from the Chubu region covered by the Chunichi Shimbun. The original article was published Jan. 20.

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