Tomatoes are the world’s most-grown vegetable for the food processing industry. Polyethylene mulch films are commonly used to increase yield by controlling weeds, soil temperature and water usage. As complete removal after harvesting is well-nigh impossible, non-degradable PE film residues find their way into the soil and accumulate there.
BASF offers a certified soil-biodegradable plastic for mulch films called ecovio® M 2351, made from its biodegradable co-polyester polybutylene adipate terephthalate (PBAT) ecoflex and other biodegradable polymers based on renewable raw materials. Mulch films made of ecovio M 2351 can be ploughed into the soil after mechanical harvest as naturally occurring micro-organisms in the soil recognize the structure of the film as food they can metabolize. Moreover, the use of mulch films made of ecovio can increase tomato yield by 15 to as much as 50 percent, while lowering water consumption and providing better weed control with less herbicides compared to bare-soil farming. Other advantages, say farmers using the films, are improved crop resistance to fungal diseases, an earlier harvest time as well as a better, more homogeneous quality of the crop and a higher Brix index, which refers to the sugar-water ratio in the tomatoes. Thus sustainable agriculture can be combined with efficient food production with higher yields and high-quality produce.
Sustainable agriculture: tried and tested in everyday farm work
Rather than being labor-intensively removed and recycled, films made from ecovio M 2351 can be left in the soil after harvesting, which saves labor and costs. A study from ETH Zürich, Switzerland, has shown that soil microbes - bacteria and fungi - can use films made from the plastic PBAT as food. The microorganisms take the carbon from the polymer both to generate energy and to form biomass. The remaining end products after biodegradation are CO2, water and biomass. This means that PBAT biologically degrades in the soil instead of fragmenting into microplastic like PE does. Soil-biodegradable mulch films are therefore also claimed to contribute to a better root development, better plant growth and improved soil quality. Ecovio M 2351 was the first material to be certified as soil-biodegradable according to the European standard DIN EN 17033. The use of mulch film made of ecovio is also accepted for organic crops in many countries.
Farmers have been using certified soil-biodegradable mulch films made of ecovio for more than six years since its introduction to the market in 2012. “We support farmers in many countries in using mulch films made of ecovio”, says Dirk Staerke from Marketing Biopolymers for Agriculture at BASF. “According to the Food and Agriculture Organization of the United Nations the global agricultural production has to grow by 70 percent if we want to feed a world population which in 2050 is expected to grow to nine billion people. Bio-degradable mulch films can contribute to this challenge without polluting the soil with non-degradable film residues.”
Benefits also for film manufacturers
Ecovio M 2351 is a ready-made compound for extrusion of thin films. It can easily be processed on conventional blown-film lines for PE. Because of its excellent mechanical properties regarding strength and tear resistance these films can be manufactured in different thicknesses of 12, 10 and 8 µm. The compound already contains slip and anti-block agents.