Scientists develop a recyclable pesticide

Scientists at the Hefei Institutes of Physical Science have developed a pesticide that, once in the soil, is controllable and recyclable.

A team led by Professor Wu Zhengyan used diatomite, iron magnesium oxide and chitosan to make a compound that can be activated by changes to pH levels in the soil.

“The release of the pesticide mixed with the additive can be easily adjusted by pH changes. The additive wraps up the drug and acts like a gatekeeper. It opens the gate and dissolves in acidic conditions,” Wu said.

He said research showed that a single-season crop only needed one spray of pesticide. During the growth of the plant, growers simply spray a weak-acid agent to activate and control the pesticide’s effect. Conventional farming needs several rounds of pesticide spray.

Wu said China’s agriculture relies heavily on the use of pesticide, which was estimated at over 1 million tons a year. However, less than 40 percent actually had an effect on crops and the rest simply washed off, contaminating soil and water.

He said the additive was magnetic, making it feasible to recover the pesticide from soil and water. “The recycling effect during our tests shows 30 percent of pesticide residue can be recovered,” Wu said.

According to the research, the pesticide showed a high adhesive ability on weak surfaces and pest epidermis.

Wu said it was still too early to put the results into commercial use as the cost of nano-material and recycling was too high for farmers.

“We take it as a stage one success and will continue to upgrade to make it more efficient and economical,” he said.