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http://biodegradablemulch.org

Biodegradable : Another Tool to Add to Your Production Toolbox

Annette Wszelaki1, Jennifer Moore1, Shuresh Ghimire3, and Carol Miles2 1Department of Plant Sciences, University of Tennessee 2Department of Horticulture, Washington State University 3Department of Extension, University of Connecticut

This material is based upon work that is supported by the National Institute of Food and , under award number 2014‐51181‐22382. 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.

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Benefits of Mulch

H.Y. Sintim, M. Flury, 2017, Environmental Science and Technology 51:1068-1069

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Problems with Plastic Mulch a

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Biodegradable Plastic Mulch

Has the potential to be a sustainable technology if it: • Provides benefits equal to mulch • Reduces labor costs for removal and disposal • Reduces landfill waste • Biodegrades completely • Causes no harm to soil ecology or environment

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What does biodegradable mean?

• Capable of being broken down via microbial activity • Biodegradation provides C source for the growth and reproduction of microorganisms • Complete biodegradation (i.e., mineralization) refers to the oxidation of the Source: Numata, 2009

compound to CO2 + H2O Slide courtesy of Ghimire and Miles, 2015.

Biodegradable Mulch Ingredients

Ingredient1 Feedstock Synthesis ERBD in soil2 Cellulose Biobased Biological High PBAT Hydrocarbon Chemical Low moderate PBS Hydrocarbon Chemical Low moderate PBSA Hydrocarbon Chemical Low moderate PCL Hydrocarbon Chemical Moderate PHA Biobased Biological Moderate high PLA Biobased Biological & Chemical Low Sucrose Biobased Biological High TPS/Starch Biobased Biological High 1 Abbreviations: PBAT terephthalate; PBS polybutylene succinate; PBSA PBS-co-adipic acid; PCL polycaprolactone; PHA polyhydroxyalkanoate; PLA ; TPS starch 2 Estimated relative rate of biodegradation; Brodhagen et al. 2015. agricultural and key features of microbial degradation. Appl Microbiol Biotechnol (2015) 99:1039–1056. Slide courtesy of Miles and Ghimire, 2015.

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Oxo-degradable Plastic

• Made with conventional plastic: high density polyethylene (HDPE), low density PE (LDPE), (PP), (PS), polyethyleneterephtalate (PET), polyvinylchloride (PVC) • Includes additives that promote oxidation of the material, triggered by UV light, heat, and oxygen • Product becomes brittle and fragments • Oxo-degradable certification tests provide no pass/fail criteria: no time limit, no percent degradation • Independent third party standard ASTM & ISO test data show small percent or no 3 years after oxo-degradable mulch film fragments utilized by soil application, Everett, WA, Photo by Andy Bary microorganisms Slide courtesy of Miles, 2017.

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Production Considerations

• Machine laying the BDM • How long do you want it to last? • More careful handling • Control • Potential for mulch adhesion

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Tips for Laying

• Manufacturers know their products best and willing to help- talk to them! • Can be laid with same equipment as polyethylene, but laying speed may need to be reduced • Take the tension off- you want the wheels to guide the laying but not put pressure on mulch

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How long do you want it to last?

• Thickness (mil) tailored to length of time crop will be in field • Also, differences in performance/ degradation due to climate

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More Careful Handling

• BDM covered beds cannot be walked on like polyethylene covered beds • More care when working close to the bed edge • Breakdown at soil edge as season progresses to be expected

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What information is lacking?

• Performance data over multiple years, multiple crops, multiple environments • Better understanding of biodegradation of commercially available mulches in different climates • Information on mulch accumulation after multiple applications • Technology to measure mulch biodegradation in soil

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Pumpkin Trials

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Project Design

• Two locations: Knoxville, TN & Mount Vernon, WA • ‘Cinnamon Girl’ pie pumpkin • 30 ft plots of 5 rows each, replicated 4 times • Seeded direct: 6/16/15 & 6/15/16 Knoxville • Transplanted: 5/28-29/15 & 5/31/16 Mt. Vernon • Harvested: 9/14/15 & 9/6/16 Knoxville; 9/16/15 & 9/21/16 Mt. Vernon • Seven treatments

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Mulch Products in Experiment

Treatment Company % Biobased Thickness (mil) 1. Bare ground 2. Polyethylene (PE) FilmTech Corp. <1 1 3. BioAgri (Mater-Bi®) BioBag USA 20-25 0.7 4. Naturecycle Custom Bioplastics >20 1 5. Organix AG (ecovio®) Organix Ag. 10 0.7 6. Experimental PLA+PHA Experimental Film 86 1 7. WeedGuardPlus Sunshine Paper Co. 100 9.4

WeedGuardPlus is a cellulosic (paper) mulch PLA: polylactic acid; PHA = polyhydroxyalkanoate; BioAgri and Naturecycle consist of /starch blends; Organix of All mulches were 48 inches in width

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Crop Data

• Mulch percent visual degradation (twice a month) • Weed counts (2 weeks after planting, mid-season, and late season) • Insect and disease scouting • Yield (marketable/total, weights and numbers) • Storage & quality evaluation (every 2 wks for 8 wks) – Weight loss - Color – Soluble solids - Dry weight

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Marketable Yield by Weight 30 a 25 ab ab bc a bc 20 a cd 15 Knoxville '15 d Mount Vernon '15 10 b b Knoxville '16 b Mount Vernon '16 b b

Marketable Yield Marketable (t/ha) 5

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Potential for Mulch Adhesion

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Fruit with Mulch Adhesion

Ghimire et al. HortScience 2018

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Percent Soil Exposure

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Percent Soil Exposure

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Summary

• Several mulches performed similarly to black plastic • Yield was significantly different in Mt. Vernon, where soil and air temperatures are cooler • Mulch adhesion unintended consequence with crops that touch the ground • Breakdown varies by location, as well as weather in a given season

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Pepper Trial

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Project Design

• Location: Knoxville, TN • ‘Aristotle’ bell pepper • 30 ft plots of 5 rows each, 7’ apart, replicated 4 times • Transplanted: 5/25/17 and 5/29/18 • Double, staggered rows 12” apart, 18” within row spacing • Harvested weekly: 7/26/17-9/19/17 and 7/16/18-8/27/18 • Eight treatments • Fertigated weekly during season

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Mulch Products in Experiment

Treatment Company % Thickness Biobased mil (µm) 1. Bare ground 2. Polyethylene (PE) FilmTech Corp. <1 1 3. BioAgri (Mater-Bi®) BioBag USA 20-25 0.7 4. Naturecycle Custom Bioplastics >20 1 5. Organix AG (ecovio®) Organix Ag. 10 0.7 6. White-on-black (ecovio®) Organix Ag. 10 0.7 7. Experimental PLA+PHA Experimental Film 86 1 8. WeedGuardPlus Sunshine Paper Co. 100 9.4 WeedGuardPlus is a cellulosic (paper) mulch PLA: polylactic acid; PHA = polyhydroxyalkanoate; BioAgri and Naturecycle consist of polyester/starch blends; Organix of polyesters All mulches were 48 inches in width

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Crop Data

• Mulch percent visual degradation (twice a month) • Weed counts (2 weeks after planting, mid-season, and late season) • Plant health ratings, insect and disease scouting • Petiole sap nitrate sampled 5 times at key growth stages (first flower buds, first open flowers, fruits 1/2-grown, 1st & 2nd harvest) • Quality evaluation - Color - Soluble solids • Yield (marketable/total, weights and numbers)

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Percent Soil Exposure

BioAgri

Exp. PLA/PHA

Naturecycle 100 100 2018 Organix 90 2017 90 80 80 Polyethylene 70 70 WeedGuardPlus 60 60 50 50 White‐on‐black PSE PSE 40 40 30 30 20 20 10 10 0 0 11 20 39 50 69 81 104 113 4 173649677895 DAYS AFTER PLANTING DAYS AFTER PLANTING

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Plant Health Ratings

35 aaaaaa35 aa a Bare ground a a a 30 a a 30 a b BioAgri b b abab 25 25 b b b Exp. PLA/PHA b 20 20 b bc Naturecycle c bcbc 15 15

(tmt avgs) cd Organix 10 10 c d Polyethylene 5 5

# healthy plants in third row row third in plants healthy # 0 WeedGuardPlus 0 3-Jul 14-Aug 11-Jul 9-Aug White-on-black 2018 2017 Number of healthy pepper plants in the data collection rows by a July 16, visual rating during the 2018 2017 and 2018 pepper growing seasons in Knoxville, TN. Healthy plants in WGP plot Stunted plants & NS pressure in PE plot

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Weed Control

• Know your weed community going in! • Nutsedge can be a BIG problem! • WeedGuardPlus excellent for controlling during critical period

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Number of Weeds (per m2)

2017 19 June 19 July 6 Sept Bare ground 88.5 a 34.1 a 38.9 ab BioAgri 1.3 d 13.4 b 37.1 b Exp PLA/PHA 17.3 bc 51.8 a 68.2 ab Naturecycle 16.0 b 43.6 a 74.3 a Organix 15.1 bc 58.3 a 84.2 a PE 3.0 bcd 34.1 a 63.0 ab WeedGuardPlus 2.6 d 6.5 b 12.1 c White-on-black 3.5 cd 35.0 a 47.5 ab P-Value <.0001 0.0019 0.0006 2018 13 June 18 July 21 Aug Bare ground 11.2 de 41.9 cd 15.5 c BioAgri 23.7 bcd 83.7 bc 165.3 a Exp PLA/PHA 144.2 a 309.5 a 179.6 a Naturecycle 29.4 bc 161.9 ab 238.7 a Organix 18.1 bcd 159.7 ab 172.7 a PE 14.7 cde 29.8 d 52.7 b WeedGuardPlus 1.7 e 15.5 d 16.8 c White-on-black 33.7 b 174.0 ab 162.3 a P-Value <.0001 <.0001 <.0001 32

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Pepper Yield

Treatment Season total fruit yield by weight

2017 yield 2018 yield % unmarketable % unmarketable (tons/ha) (tons/ha) 2017 2018 Bare ground 35.8 ab 24.4 a 5.7 19.3 BioAgri 37.9 a 8.7 bc 8.9 28.2 Exp. PLA/PHA 27.7 ab 7.4 bc 10.5 30.3 Naturecycle 17.3 c 8.7 bc 13.0 23.1 Organix 26.8 bc 5.4 c 10.8 33.3 Polyethylene 33.8 ab 1.3 c 11.9 50.0 WeedGuardPlus 34.9 ab 22.1 a 9.7 31.6 White-on-black 33.7 ab 15.7 ab 13.3 31.4 P-value 0.0053 <.0001

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Pepper Yield by Size Classes

Treatment Marketable size classes - season total fruit (tons/ha) 2017 2018

Small Medium Large Choppers Small Medium Large Choppers

Bare ground 8.02 ab 8.85 10.62 ab 5.07 ab 4.68 a 5.83 a 4.88 a 3.67 a BioAgri 7.02 abc 8.36 12.29 a 3.94 bc 1.83 bc 1.57 bcd 1.38 bc 1.44 bc Exp. PLA/PHA 5.52 bc 7.82 7.17 abc 2.64 cd 1.47 bc 1.38 bcd 0.98 bc 1.24 cd Naturecycle 4.77 c 4.01 3.74 c 1.77 d 1.18 bc 2.15 bcd 1.76 bc 1.06 cd Organix 6.14 bc 5.69 6.19 bc 3.98 b 0.92 bc 1.01 cd 1.03 bc 0.58 cd Polyethylene 6.89 abc 7.07 9.21 ab 4.67 ab 0.24 c 0.14 d 0.04 c 0.23 d WeedGuard 10.03 a 8.12 7.26 abc 5.25 ab 4.25 a 3.60 ab 3.59 ab 3.39 a W-o-B 7.19 abc 7.49 6.12 bc 7.53 a 2.61 ab 2.29 abc 2.44 ab 2.80 ab P-value 0.0425 0.0622 0.0460 <.0001 0.0006 0.0027 0.0119 <.0001

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Summary

• Transplants established more quickly in WOB, paper and bare ground plots, likely due to excessive heat; all treatments equalized later in 2017, but not in 2018 • Lower seasonal total yields in PLA/PHA, Organix and Naturecycle due to nutsedge infestation in 2017 • Heat and nutsedge more severe in 2018 leading to reduced yields compared to 2017 • WOB had the highest % of unmarketable fruit in 2017; PE had the highest % of unmarketable fruit in 2018 • Paper degraded quickly, but was only treatment that prevented nutsedge emergence and prevented weeds during critical period

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Sweet Corn Trial

Photo courtesy of Miles, 2019.

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Percent Soil Exposure

2017 2018 100 100 80 80 60 60

PSE 40 40 20 20 0 0 8 2238527084100 10 24 41 56 71 85 99 115 DAYS AFTER SOWING DAYS AFTER SOWING

Slide courtesy of Miles, 2019.

Mulch deterioration

14 July 2017

‘Xtra-Tender 2171’ sweet corn

BioAgri PLA/PHA Naturecycle

PE

Organix-Black Organix-Clear WGP Slide courtesy of Miles, 2019.

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Sweet Corn Yield (t/ha)

Treatment 2017 2018 Polyethylene 12.1 a 19.8 a Exp. PLA/PHA 10.0 abc 19.9 a BioAgri 9.6 bc 17.1 b Naturecycle 9.3 bc 19.8 a Organix Black 10.2 abc 18.6 ab Organix Clear 7.6 cd 17.6 b WeedGuardPlus 5.6 d 13.9 c Bare ground 6.5 d 13.7 c P-value 0.0003 <0.0001 Slide courtesy of Miles, 2019.

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Conclusions

• BDMs have a bit of a handling learning curve • Several BDMs performed comparably to polyethylene • Consider your weeds before choosing a mulch • More work to be done! • Stay tuned…

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Acknowledgements

USDA SCRI Project No. 2014-51181-22382

Douglas Hayes (PD), Annette Wszelaki, Jennifer DeBruyn, Markus Flury, Eric Belasco, Sean Schaeffer, Arnold Saxton, Susan Schexnayder, Margarita Velandia, Larry Wadsworth, Mark Fly, Carol Miles, Debra Inglis, Thomas Marsh, Jessica Goldberger, Suzette Galinato, Chris Benedict, Ting Chi, Hayley Chouinard, Jeremy Cowan, Peter Tozer, Andy Bary, Lydia Tymon, Katie Dentzman, Jennifer Moore, Amy Salamone, Babette Gunderson, Ed Scheenstra, Jacky King, Marie English, Sreejata Bandopadhyay, Marife Anunciado, Shuresh Ghimire, Henry Sintim, Kuan Chen, Sarah Bellingham, Jose Liquet y Gonzalez This material is based on work supported by the National Institute of Food and Agriculture, under award number 2014-51181-22382. Any opinions, findings, conclusions or recommendations expressed in this presentation are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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Thank you! Questions? [email protected]

For more information: www.biodegradablemulch.org

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