Evaluating Potential Biodegradable Mulches for High Tunnel and Field Vegetable Production

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Season Extension and Weed Management High
Tunnels and Biodegradable Mulches Carol Miles,
Vegetable Specialist Jeremy Cowan, Ph.D.
Student Department of Horticulture WSU Mount
Vernon NWREC
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Biodegradable Mulches for Specialty Crops
Produced Under Protective Covers Debra Inglis
and Carol Miles (Project Directors)1 Andrew
Corbin, Jessica Goldberger, Karen Leonas, Tom
Marsh and Tom Walters1 Doug Hayes, Jaehoon Lee,
Larry Wadsworth and Annette Wszelaki2 Jennifer
Moore-Kucera3 Russ Wallace4 Marion Brodhagen5
and Eric Belasco6
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SCRI Project Goals for High Tunnels

• Assess agricultural and economic impacts of
  using high tunnels as compared to open field for
  tomato, lettuce and strawberry production
• Compare performance of biodegradable mulch (BDM)
  in high tunnel and open field
• Compare high tunnel structures in three diverse
  locations in the U.S. with focus on wind
  tolerance and labor requirements

Nanjing Agricultural University, Nov 11
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Definitions

• DegradeMeasurable conversion of C to CO2 through
  abiotic factors such as heat, UV light, or
  mechanical stress.
• Biodegrade
• Break down via microbial activity ultimately the
  oxidation of the parent compound to carbon
  dioxide and water, providing carbon and energy
  for the growth and reproduction of cells.
• Deteriorate
• Loss of physical or mechanical strength as
  observed through physical testing, microscopic
  imaging or visual assessment.

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Field Experiments

• Variety trials 6 cvs tomato 6 cvs lettuce 6
  cvs strawberryBDM trial with tomato cv.
  CelebrityLocations Mount Vernon WA, Lubbock TX,
  Knoxville TN
• Experimental design
• Randomized complete block with four replications
  
• Main plot high tunnel and open field
• Subplots 3 feet wide bed, 14 feet long
• BDM planted with tomato
• Plots managed organically
• BDM experimental treatments
• 1) Experimental fabric SB-PLA
• 2) BioBag starch-based (Mater-bi) film
• 3) BioTelo starch-based (Mater-bi) film
• 4) Sunshine paper cellulose, 100 degradable
• 5) Standard black plastic PE, 1.0 mil embossed
• 6) Bare ground / non-mulch control

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Mount Vernon, WA
Lubbock. TX
Knoxville, TN

• High tunnels provide
• Increased heat
• Protection from rainfall
• Reduced leaf wetness
• Increased crop yield
• Shortened time to harvest for many crops

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Climate Comparison for HT and OF - 2010
  Mount Vernon, WA Mount Vernon, WA Lubbock, TX Lubbock, TX Knoxville, TN Knoxville, TN
  HT OF HT OF HT OF
GDDy (base 10 oC) 1007 740 1799 1661 1795 1463
Ave. daily max. air temp. (oC) 24.2 21.1 31.9 32.6 34.2 33.5
Ave. daily min. air temp. (oC) 10.5 9.7 24.7 18.9 17.5 18.7
Ave. soil temp at 5 cm depth            
BioBag 18.9 17.7 26.2 25.6 26.2 27
BioTelo 19.3 18.1 25.9 26.6 27 26.8
SB-PLA-10 18.7 17 24.9 24.6 26.5 26.6
Weed Guard Plus 18.3 16.7 26.9 26.6 25.7 26.3
Black Plastic 19.8 18.9 27.2 28.2 27.8 27.3
Bare Ground 18.7 16.8 24.9 25.2 26.9 26.7
Ave. sol. rad. (µmolm-2s-1) 0.36 0.44 0.35 0.54 0.41 0.57
Relative Humidity () 79.7 81.3 66.2 66.7 74.1 79.2
Ave. wind speed (kmh-1) 1.1 3.3 0.2 6.4 0 1.9
Total rainfall (mm) 0 235.5 NA 333.5 0 156
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Tomato Yield High Tunnel and Open Field at Mount
Vernon 2011
Total Number (plot-1)
Total Weight (kg.plot-1)
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Lettuce Yield High Tunnel and Open Field at
Mount Vernon in 2011
Total Weight (kg.plot-1)
Marketable Weight (kg.plot-1)
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• Plastic mulch provides
• Weed control
• Conservation of soil moisture
• Increased crop yield
• Modified soil temperature
• Shortened time to harvest for many crops

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Plastic mulch must be removed from the field for
disposal in-field incorporation and
biodegradation would eliminate disposal costs
Rick Boydston, USDA ARS
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Skeletal formula of poly(lactic) acid
Bacillus subtilis
poly-(R)-3-hydroxybutyrate

• Biodegradable mulch generally made from
• Poly(lactic) acid (PLA)
• - plant-based polyester produced from starch
• Polyhydroxyalkanoates (PHA)
• polyesters produced by bacterial fermentation of
  sugar or lipids

Andrew Corbin, WSU Extension
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Presumed Mulch (Bio)Degradation
Doug Hayes, UTK
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SCRI Project Goals for Biodegradable Mulches

• Assess agricultural, ecological, and economic
  consequences of using biodegradable mulches in
  high tunnels and open field
• Test PLA-based spunbond as mulch prototype
• Compare PLA and commercial biodegradable
  mulches for performance in growing tomatoes
• Provide data that may be useful for developing
  an ASTM standard for biodegradation of mulches in
  soil

Nanjing Agricultural University, Nov 11
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SCRI Project Experimental BDM

• CollaboratorsNature Works (U.S.), Saxon Textile
  Research Institute (Germany), and GreenBio
  (China)
• Experimental PLA mulch for field testing
• SB-PLA-10 high MW, white
• SB-PLA-11 half MW of (10), small fiber size,
  black
• SB-PLA-12 blended with PHA (20), black

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High tunnel
September 23, 2010 Mount Vernon
Open field
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Weed Control with Biodegradable Mulch High
Tunnel and Open Field, Mount Vernon 2010
Total Number (plot-1)
Total Weight (g.plot-1)
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Tomato Yield with Biodegradable Mulch High
Tunnel and Open Field, Mount Vernon 2011
Total Number of Fruit (plot-1)
Total Weight of Fruit (kg.plot-1)
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Mean Tomato Fruit Quality with Mulches High
Tunnel and Open Field, Mount Vernon 2011
Fruit Acidity
Fruit oBrix
Supported by CSANR BIOAg grant
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Mulch Visual Evaluations
BioBag 6/17/11
8/1/11 9/2/11
10/10/11

• Two times each month measure
• Number of rips, tears and holes (RTH)
• Percent visual deterioration (PVD)

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BDM Percent Visual Deterioration High Tunnel and
Open Field 2010 Mount Vernon and Knoxville
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Mulch - Laboratory TestingFirst Flower
SB-PLA-10
SB-PLA-11
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BDM Sample PreparationFirst Flower
BioTelo
BioBag
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BDM Sample Degradation
BioBag
BioTelo
Planting
Final Harvest
Karen Leonas, WSU
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BDM Maximum Load at Final Harvest2010 HT and
OF at Mount Vernon, Lubbock Knoxville
High Tunnel
Open Field
Doug Hayes, UTK
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Mesh Bag Study Mount Vernon 2011
BB TX Mar 2011
BT TX Mar 2011
Oct 2010
Jennifer Moore-Kucera, TTU
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Current Status

• Year 2 field studies complete data are being
  entered and analyzed
• Year 1 and Year 2 preliminary reports posted on
  Team website http//mtvernon.wsu.edu/hightunnels/
  
• Year 1 results are being submitted for
  publication Winter 2011
• Developed a team website and public website for
  information sharing