SINGAPORE (Reuters) — Bulging cotton inventories in China and slumping oil markets have triggered a race to the bottom between cotton and polyester prices. Both fibers compete for buyers in the textile industry, and cotton seems to be gaining the upper hand for the first time in years.

U.S. cotton futures have fallen by a third since early 2014, and in January, hit a six-year low around $1,260 a tonne. Futures prices in China, both the world’s largest producer and importer, are also down a third.

Prices for polyethylene terephthalate (PET) polymers, the main petrochemical used in polyester, dropped in 2014 as well, but have bounced by 16 percent since the start of the year along with steadying crude prices, to about $1,000 a tonne.

The price slide for PET polymers began in June last year when soaring global crude production was met by a slowdown in demand, pushing oil prices down by more than half.

But the forces driving down cotton have been stronger. In September, Beijing said it would cut back its fiber import quota to help spur domestic production as well as wind down a massive stockpiling program. That significantly reduced U.S. exports to China, and added supply to a global cotton market already facing bearish fundamentals, including rising world production and a surging U.S. dollar.

Although the price falls hurt producers of cotton, which remains more expensive than PET, the narrowing gap may finally halt a protracted slide in demand. For years, polyester made inroads against consumer preferences for cotton, in part through the development of advanced fibers.

After a sharp fall in cotton use from mid-2010 to mid-2012, driven largely by polyester’s price advantage, cotton consumption is again edging up.

The U.S. Department of Agriculture said in its latest monthly outlook that, while stocks would remain high for years, for the 2015/16 July-June crop year, “world cotton projections anticipate that consumption will exceed production for the first time in six years.”