DEGRADABLE MULCH FOR AGRICULTURE: YEAR 1 …agsyst.wsu.edu/scri/Wadsworth-FS-May-2011.pdfDEGRADABLE...
Transcript of DEGRADABLE MULCH FOR AGRICULTURE: YEAR 1 …agsyst.wsu.edu/scri/Wadsworth-FS-May-2011.pdfDEGRADABLE...
DEGRADABLE MULCH FOR AGRICULTURE:
YEAR 1 COMPREHENSIVE ANALYSIS OF A FIELD STUDYKaren K. Leonas1, Hang Liu1, Jeremy Cowan4, Douglas G. Hayes2, Larry C.Wadsworth2, Russell Wallace3, Carol Miles4, Annette Wszelaki2, Jeffery Martin2 andDebra Inglis4
1Washington State University, Pullman, WA, 2University of Tennessee, Knoxville, TN, 3Texas A&M University, Lubbock, TX, 4Washington State University, Mount Vernon, WA
SCRI-SREP Grant Award
No. 2009-02484
USDA Hatch Act: Multistate Regional Project – S 1026
Contact First Author at [email protected]; Contact Speaker at [email protected]
The Fiber Society Spring 2011 Conference, The Hong Kong Polytechnic University, Hong Kong, May 23-25, 2011
Biodegradable Mulches for Specialty Crops Produced
Under Protective CoversDebra Inglis and Carol Miles (Project Directors)1;
Curt Beus, Andrew Corbin, Ana Espinola-Arredondo, Karen Leonas, Tom Marsh and Tom Walters1;
Doug Hayes, Bobby Jones, Jaehoon Lee, Larry Wadsworth and Annette Wszelaki2;
Eric Belasco and Jennifer Moore-Kucera3;
Russ Wallace4; and, Marian Brodhagen5
1 2 34
5
SCRI-SREP Grant Award
No. 2009-02484
Introduction
Background
•Mulches as a row cover can provide:
�Conservation of soil moisture
�Modifies soil temperature
� Increases crop yield
�Shortens time to harvest
•Traditional mulches are:
�From non-renewable petroleum feed stocks
� In many regions non-recyclable
�Labor intensive to remove
�High disposal cost
� If not removed cause soil erosion
Biodegradable Mulches
• Investigation of Biodegradable Mulches (BDM)
• Life expectancy – preferably less than one year and non-accumulating in soil
• Till back into soil without negatively impacting soil ecosystem
- Need to maintain a healthy microflora/fauna with no release or accumulation of foreign or toxic substances
Biodegradable Mulches
• Reviews changes in tensile strength, elongation, and tearing strength of 5 mulches
– 3 marketed as biodegradable
– 1 non-biodegradable
– 1 experimental nonwoven from PLA fibers
• Analyzes Mn of 3 mulches up to 20 weeks
• Year 1 of a 3 Year study
This presentation
Methods and Materials
A tomato cultivar plot in TN
Experimental Design
• 5 Mulches � Biobag �BioTelo �Spunbond PLA� Non-biodegradable PE �Cellulosic
• Locations�WA �TN �TX
• Evaluation Times� Control �Field control �First flower �Final harvest
• Environments� Inside high tunnel �Open field
5 mulches x 4 times x 3 locations x 2 environments x 4 replications
General Protocol
• Mulch samples cut from predetermined locations, which were not covered with soil in row, cleaned & sent for testing (WSU Pullman)
• If necessary, additional cleaning was completed in Pullman
• In a separate study, specimens of each mulch have been put into nylon open mesh bags along with soil and buried in same plots without mulch cover and analyzed at different times for up to two years for degradation
Laying mulch (WA) Cutting SB (WA) Transplanting vegetables (WA)
PLA
Cellulose
Polyethylene
(non-biodegradable)
(C6H10O5)n
Corn Starch (BioBag, BioTelo)& Non-disclosed Biopolymer(s)
Chemical Structures of MulchesChemical Structures of Mulches
Mulches
SCRI Project Locations
WSU Mount Vernon
TA&M Lubbock
UT Knoxville
WSU Pullman –
Materials Testing
& Materials Analysis
Sampling Time Dates
Time 1 - Mulch Laid
Time 2 - First FlowerTime 3 - Final Harvest
Environment
In High Tunnel Open Field
Testing:
Physical properties measured to evaluate degradation
&
Property Test Method Test equipment
ThicknessASTM D5729-97 Test method for thickness of textile materials
(10 specimens)
Digital Micrometer M121 (Testing
Machines Inc.) (test range: 0.01mm ~
20mm)
WeightASTM D3776-07 Test method for mass per unit area (weight)
of fabric (5 specimens)
Balance ( BC 100) (test range: 0.001g ~
210g)
Stiffness
IST 90.2 (01) Standard test method for stiffness of nonwoven
fabrics using the Gurley Tester (5 specimens for each fabric
direction)
Bending Resistance Tester (Gurley
Precision Instrument) (test range: 2.78mg
~ 335328mg)
Tearing strength
ASTM D5734-95(2001) Test method for tearing strength of
nonwoven fabrics for by falling-pendulum (Elmendorf)
apparatus (5 specimens for each fabric direction)
Digital Elmendorf Tearing Tester (Tonny
International Co. LTD) (test range: 160cN
~ 3840cN)
Tensile properties
ASTM D5035-06 Test method for breaking strength and
elongation of textile fabrics (Strip method) (5 specimens for
machine direction and 8 specimens for cross direction)
Instron 5565A (Instron Corporation) (test
range: 0.4N ~ 5000N)
PorosityNo standard test method applies. (Ten specimens were tested
following the equipment instruction manual)
Capillary Flow Porometer CFP-1200AEX
(Porous Materials, Inc.) (test range:
0.013µm ~ 500µm)trR
Resistance to
weathering
ASTM G155-05a Standard practice for operating xenon arc
light apparatus for exposure of non-metallic materialsAtlas Ci 3000+ Xezon Weather-ometer
Molecular Weight &
Polydispiserty
No standard test method applies. (Three specimens per
sample were tested)Gel Permeation Chorography
Biodegradation
In soil
ASTM D 5988 Test method for determining aerobic
biodegradation in soil of plastic materials or residual plastic
materials after composting
As specified in test method
Test methods to measure mulch properties
Sampling Plan for Laboratory Testing
Tensile/elongation
Tearing Strength
Flexibility
Porosity
Results and Conclusions
Photos:
Mulch after exposure
Micrographs :
Time 0 & Time 3
Properties Reported:
Maximum load (machine direction)
Maximum elongation(machine direction)
Molecular Weight
Influence of:
Location
Environment
Time
Tensile PropertiesTime 0 – Maximum Load – Machine direction
Time 0 – Maximum Load – Machine direction
Time 0 - % Elongation – Machine Direction
Year 1 Tearing Strength Graphs – Machine Direction
Time 0 Tearing Strength (g)
Time 0/1 Time 2 Time 3
TN
TX
WA
BioBag
Time 0/1 Time 2 Time 3
TN
TX
WA
BioTelo
Time 0/1 Time 2 Time 3
TN
TX
WA
Non-biodegradable
Time 0/1 Time 2 Time 3
TN
TX
WA
Cellulosic
Time 0/1 Time 2 Time 3
TN
TX
WA
SB PLA
Time 0 Time 3
(HT – TX)BioTelo
Magnification 20000x
Time 0 Time 3
(FD – TX)
Non-biodegradable
Magnification 1000x
Time 0 Time 3
(FD – WA)
Cellulose
Magnification 500x
Time 0 Time 3
(HT – WA)
SB PLA
Magnification 100x
Time 0 Time 3
(FD – WA)
SB PLA
Magnification 2000x
Time/Location/EnvironmentPercent Maximum Load
Time/Location/EnvironmentPercent Maximum Elongation
Time 0 Time 3
(FD – HT)
BioBag
Magnification 20000x
Comparison of Locations/Environment
Percent of Maximum Load at Time 3
Open Field High Tunnel
Time 3 – Field - % Elongation – Machine Direction
- Comparison of Locations/Environment
Time 3 – HT - % Elongation – Machine Direction
- Comparison of Locations/Environment
Time 3 – Field - Tearing Strength – Machine Direction
– Comparison of Locations/Environmen
Time 3 – HT - Tearing Strength – Machine Direction
– Comparison of Locations/Environmen
Time 3 Tearing Strength – Machine Direction – Comparison of FD & HT
Spunbond PLA
BioTelo
BioBag
Conclusions
• Loss of strength & elongation influenced by mulch treatment
• Environment (Field vs High Tunnel)
� In general, reduction in elongation was greater for those products in the field environment compared with the high tunnel by end of exposure (Time 3).–Cellulose & SB PLA – greater reduction in Field for all locations
�However, reduction in tensile strength varied based on mulch and location–Cellulose & SB PLA – greater reduction in Field for all locations
Conclusions – con’t
• Location (WA vs TN vs TX)
� Based on current analysis, one location did not consistently result in the greatest property loss
•Time
� In all cases, regardless of mulch/location/ environment –Tensile and tearing strength and elongation values decreased during exposure
Conclusions – con’t
•Molecular Weight
�Mn of SB PLA in HT and FD appeared to decrease slightly with time in all three locations
�With BioBag, Mn decreased with time in all environments. After T3, TX HT and TN HT showed the largest decrease, followed by TN field, WA HT and WA field
�With BioTelo, Mn also decreased with time in all three environments. After T3, the largest decrease occurred with TN HT and TX FD, followed by TN FD, WA HT, WA FD and TX HT
Future Work•Completion of Year 1 of 3 Year Study
• Based on results to date,
�modifications are being made to the PLA Mulch to be used in Year 2 and in Year 3
� Evaluation of tests that best predict degradation
•Analysis of samples buried in soil in nylon mesh bags for degradation
• Laboratory accelerated weathering and other conditions of exposure (sunlight, temperature, relative humidity, and soil moisture content) will be studied