Worm has turned on pesticides, chemicals

Organic farming projects are making strides in tapping the natural world instead of relying on chemical fertilizers and pesticides.
Jiang Xiaowei / SHINE

A farmer turns over earthworm rich soil at a greenhouse of Alin Fruit and Vegetable Garden in Jinshan District.

Urbanites rarely give a passing thought to earthworms, but to farmers the natural environment contains many annelid and insect friends that promote higher yields without the use of chemical fertilizers and pesticides.

Consider the humble earthworm. Its castings increase soil nutrients, improve drainage and contribute to stable soil structure.

At China’s recent first farmers’ harvest festival, the symbiotic relationship between farms and the natural world was celebrated. It was in with organic production methods and out with chemical dependence.

In June, Shanghai began a 16-month program on crop rotation. During the project, local vegetable producers will leave part of their land fallow, introducing earthworms to improve the soil.

Alin Fruit and Vegetable Garden in suburban Jinshan District is a test site, with 17 hectares of land allocated to the project.

Farmer Zhang Xiaotuan pointed to a small plot in a greenhouse where hundreds of earthworms were living. He said fruits and vegetables grown on land rich in earthworms taste better.

About 500 earthworms per square meter of land can increase soil permeability by up to 30 percent, and soil nutrients rise at least 15 percent, according to Jiang Lianhui, who is responsible for the earthworm cultivation.

Jiang Xiaowei / SHINE

The Orius insidiosus, or insidious flower bug, feeds on pests such as aphids.

Organic farming methods also include biological fertilizers such as manure and crop stalks.

Alin Fruit and Vegetable Garden is among the city’s first farms to use earthworms on a big scale.

“We started breeding earthworms in May 2014, when our boss decided to switch to organic farming and needed methods to improve the soil,” Jiang told Shanghai Daily. “At that time, bio-fertilizers were not that common, so we raised earthworms.”

The project started out small but gradually expanded, becoming a demonstration site for the local agricultural commission.

“The castings of earthworms contain large amount of nutrients and amino acid,” said Jiang. “On land where we breed earthworms, we don’t need to fertilize for a year.”

Most earthworms can live up to 50 days, and their reproduction cycle is very fast. Since earthworms like humidity and darkness, the worm farm is watered once every three days in summer, with sunshades used to filter out bright rays. To ensure that no harmful bacteria, plant diseases or insect pests thrive in the worm breeding areas, crop rotation is used to create fallow land that is alternated every year with cultivated land.

Besides earthworms for fertilizer, natural enemies are also employed for biological pest control in Jinshan District.

At the Langxia Fruit and Vegetable Garden, insects such as ladybugs are used to eradicate insect pests.

Liao Changgui, general manager of the garden, told Shanghai Daily that natural enemies control pests such as mealywing bugs, thrips, aphids and spider mites.

“With pesticides, insect pests are reduced after application but rise again when the application is reduced,” said Liao. “But with natural enemies, a balance is achieved that remains.”

Jiang Xiaowei / SHINE

Ladybugs eat the larvae of silverleaf whitefly and aphid whitefly.

According to Liao, only about 5 percent of pesticides really act on plants. The rest is transferred to the soil and air, causing pollution.

“The application of natural enemies requires very skilled work,” said Liao.

“Last year when I released the natural enemies, I wasn’t growing the right plants for them to feed, so they died and contributed nothing to bio-control.”

This year he selectively planted crops that attracted natural enemies. Then there was the problem of the seasonal nature of different plants. If a crop that hosts a natural enemy dies, another crop is needed to continue feeding them.

Liao discovered that tobacco, rapeseed and sesame host one particular natural enemy, so he can alternate those crops to keep his bio-friends alive year round.

“Ladybugs eat both the larvae of silverleaf whitefly and aphids,” he said. “So in winter, we will plant some wheat which will easily produce aphids for lady beetles to eat.”

Natural enemies save both labor and costs. Pesticides require repeated applications; natural enemies are there all the time if there is food for them.

Liao hopes scientific research centers will be set up to help farmers use bio-friendly pest exterminators.

According to the Shanghai Agricultural Commission, land covered in the crop rotation project will exceed 66,667 hectares this year. Last year, the application of chemical fertilizers was reduced to 89,000 tons, nearly 30,000 tons less than in 2010.

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