Since the fall of 2019, efforts have been made to clean up the PE. As of 2024, PE that was not harvested, is now imbedded 4-6” beneath the surface. In adversity, there is opportunity. Based on the farm owner’s experiences in chemistry and biology, we contacted OSU to develop a protocol to remove plastic mulch using ultrasonication procedures and fungus.

Joint Venture Agreement with USDA Natural Resources Conservation Services, Oregon State University and Santiam Valley Ranch.

The goal of the Joint Venture Agreement ($500,000 for the 4-year project) is to:

• Develop the procedure to break the tight-holding carbon molecules bonded together that forms polyethylene.

• Once the carbon bond is broken, identify funguses (of which there could be several) that will digest carbon and which can tolerate the climate and soil of this area.

• Apply the results gained from achieving goals 1 & 2 to a pilot site at Santiam Valley Ranch.

  The work at OSU is coordinated by Dr. Gerald Presley, Department of Wood Science & Engineering, College of Forestry, PhD student Leon Rogers and Master student, Javier Illesas. In addition to addressing fungal decomposition of PE, the project has expanded to study the effects of biochar that sorbs microplastics and biosolids which can contain forever chemicals (PFAS) and also is absorbed by biochar. This work is supported by Freres Engineered Wood, Lyons, Oregon, that supplied 360 tons of biochar to this project, and to Willow Lake Wastewater Treatment Facility, Salem, OR, that has provided biosolids. Workshops sharing the information glean for this effort has occurred at OSU (if interested in learning more, contact Kathy). The project was covered by the November 1, 2024 Capital Press.

In 2017, a 10-year lease was executed to grow cannabis for CBD oil which would be certified as “organic.” Late springs brought late planting times complicated by early winters that brought debilitating fungus to the hemp. The lease was terminated with the understanding that all plastic mulch would be removed. Regrettably, the hemp farmer purchased non-commercial, low-cost sheeting and did not remove the sheeting for two years.

Polyethylene Mulch. “Plastic mulch”, made of polyethylene (PE), is used to suppress weeds and conserve water in crop production. To apply plastic mulch a machine called a “plastic layer” is pulled over the planting area and creates the raised planting bed. Simultaneously, the bed is covered by plastic sheeting via a roller. Two coulters cover the edges of the plastic film with dirt and hold the plastic tightly onto the soil’s surface. Simultaneously, while laying the plastic sheeting, drip line irrigation is placed under the sheeting. Once installed, holes are cut into the sheeting and transplants are placed into each hole. By using plastic mulch, weeds are suppressed thus minimizing the use of herbicides and offering opportunities to those seeking organic crop designation. The use of drip lines reduces the need for large irrigation systems, avoids wasteful use of water, and holds moisture near plant roots. By use of the drip tube, specific organic fertilizers can be injected into the irrigation water and applied directly at the plant’s roots. After the crop is harvested, the plastic mulch should be removed using the plastic mulch “lifter” which wraps up the sheeting and drip line. The plastic is disposed of as garbage. (Recycling of plastic mulch poses significant environmental problems because it is likely contaminated with agrochemicals (dispersed through the drip line) and is covered with dirt and maybe too contaminated for recycling.) Mulch can be used in the same place for a second or third year. With each successive year, the sheeting is deteriorating due to damage from ultraviolet light, winter weather, and/or damage caused by livestock or waterfowl using the field. Eventually, the lifting machine becomes ineffective and unless the mulch is removed by hand, the mulch remains on the landscape. Routine agricultural preparation of fields, including plowing, disking or rototilling, further dismembers the sheeting. Residual microplastics are imbedded in the soil, having negative effects on soil ecologies, including microbes and earth worms, and can be eaten by livestock and wildlife, including migratory waterfowl. Today, the application of plastic mulch is predominant for large-scale vegetables and is used on millions of acres cultivated under plastic mulch worldwide each year. Due to climate change and increasing scarcity of water, using plastic mulch in undeveloped countries has become the norm. 92% of petroleum-based polymers used in agriculture are polyethylene and polypropylene, with the vast majority being polyethylene. Because of the need to protect limited resources such as water and to veer away from continued use of herbicides and fertilizers, the use of plastic mulch and its removal is of international concern. Polyethylene can survive hundreds of years as a non-decomposed substance.