Biodegradable plastic mulches: performance, degradation, and impacts on agroecosystems

Project Overview

GW17-019
Project Type: Graduate Student
Funds awarded in 2017: $23,063.00
Projected End Date: 01/31/2019
Grant Recipient: Washington State University
Region: Western
State: Washington
Graduate Student:
Major Professor:
Markus Flury
Washington State University

Annual Reports

Commodities

  • Vegetables: cucurbits, peppers, sweet corn

Practices

  • Education and Training: demonstration, workshop
  • Production Systems: general crop production
  • Soil Management: soil analysis, soil quality/health

    Abstract:

    The use of polyethylene mulch in agriculture can lead to environmental problems because of limited disposal options. Biodegradable plastic mulch‒designed to decompose into carbon dioxide (CO2), water, or incorporated into microbial biomass‒could alleviate the disposal problem. The sustainable application of biodegradable plastic mulch will, however, depend on performance, degradability, and effects on agroecosystems. Four biodegradable plastic mulches were tested in hot humid (Knoxville, TN) and cool humid (Mount Vernon, WA) climates in the United States under pie pumpkin (Cucurbita pepo), sweet corn (Zea mays), and green pepper (Capsicum annuum) production. No-mulch, paper mulch, and polyethylene mulch were included as control treatments. The amount of water used for crop production was similar under all mulch treatments. However, the water was efficiently utilized under the biodegradable plastic mulches than the no-mulch and paper mulch, but similar when compared to that in polyethylene mulch. In addition, the biodegradable plastic mulch modulated soil microclimate better than the no-mulch, but not as well as when compared to the microclimate under the polyethylene mulch. The biodegradable plastic mulches affected various soil health indicators (physical, biological, and chemical), with the effect being mostly positive. However, the effects on soil health were not consistent among the mulches, across the two sites, and over the different assessment times. Overall, the biodegradable plastic mulches degraded at a slow rate in soil: 61% to 83% in Knoxville and 26% to 63% in Mount Vernon after 36 months. However, paper mulch which served as a positive control degraded, approximately, 100% within 12 months. Degradability of the biodegradable plastic mulches was also tested in compost, and they underwent 85% to 99% degradation after just 18 weeks. Although the mulches degraded well in compost, micro and nanoparticles were released, which were mostly conglomerate of carbon material. Field days and workshops focused on biodegradable plastic mulch installation, till-down, degradation, and the art and science of composting were organized, and well attended by producers and other relevant stakeholders. In addition, several presentations, publications, extension bulletin, research reports, and other outreach materials were prepared. Through the outreach activities conducted during this project, we were able to reach about 700 different people.

    Project objectives:

    The overall goal of the project is to improve the productivity and environmental sustainability of specialty crop production by evaluating biodegradable plastic mulch as an alternative to polyethylene-based plastic mulch.

    Specific objectives:

    Objective 1: Evaluate the performance of biodegradable plastic mulches       

    Objective 2: Determine the effects of biodegradable plastic mulches on agroecosystems

    Objective 3: Evaluate the degradation of biodegradable plastic mulches

    Objective 4: Engage and educate producers

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.