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The 2011 ASHS Annual Conference

6926:
Biodegradable Mulches: Short-Term Degradability and Impacts On Soil Health

Sunday, September 25, 2011: 2:45 PM
Queens 6
J. Moore-Kucera, Plant & Soil Sciences, Texa Tech University, Lubbock, TX
Marko Davinic, Plant & Soil Sciences, Texas Tech University, Lubbock, TX
Lisa Fultz, Plant & Soil Sciences, Texas Tech University, Lubbock, TX
J. Lee, Biosystems Engineering & Soil Sciences, University of Tennessee, Knoxville, TN
Carol A. Miles, Horticulture and Landscape Architecture, Washington State University, Mount Vernon, WA
M. Brodhagen, USDA-ARS, Corvallis, OR
J. Cowan, Washington State University, Mount Vernon, WA
Russell W. Wallace, Horticultural Sciences, Texas A&M University, Lubbock, TX
Annette L. Wszelaki, Plant Sciences, University of Tennessee, Knoxville, TN
Jeff Martin, Plant Sciences, University of Tennessee, Knoxville, TN
Jonathan Roozen, Snohomish County, Washington State University Extension, Everett, WA
B. Gundersen, Horticulture and Landscape Architecture, WSU Mount Vernon, Mount Vernon, WA
Debra Inglis, Department of Plant Pathology, Washington State University, Mount Vernon, WA
A three-year SCRI research project (#2009-02484) is evaluating experimental and currently available biodegradable mulch (BDM) products in high tunnel (HT) and open-field (OF) tomato production systems in three distinct eco-regions of the U.S. [Southeast (TN); Pacific Northwest (WA); and High Plains (TX)]. BDM treatments include: an experimental spunbond (SB) poly-lactic acid; two commercially-available BDM starch-based films [BioBag (BB) and BioTelo (BT)]; a cellulose-based product [WeedGuardPlus (CC)]; and a no-mulch control (NM). Plots are arranged as a RCBD with four replications. Visual assessment of number of tears and % degradation of mulch pieces was performed throughout the growing season. Following the 2010 tomato harvest, mulch was removed and plots were tilled. A set of nylon mesh bags (161cm2) containing one piece (103cm2) of each BDM and resident soil was buried (8–10cm depth) at each site for up to two years. At the end of the growing season (pre burial), mulch degradation was 3% and 24% greater in OF than in HT at WA and TX, respectively (TN analysis pending), and overall mean % degradation was 32% for CC, compared to 23% and 17% for BT and BB, respectively. The first set of mesh bags are being extracted at each location before spring tillage to determine % area reduction and impacts on soil chemical (pH, EC, total C, N); biochemical [N mineralization potential (Nmin), beta-glucosidase, and N-acetyl-beta-glucosaminidase activities], and microbial properties [biomass carbon (MBC), community composition, and identification (microorganisms capable of utilizing BDMs as a sole C source)]. Only two of four CC reps for TN-HT samples, had decreased surface area (93–98% reduction) after 6-months field incubation. In contrast, moderate degradation had occurred in TX-HT in BB and BT (5–46% reduction), and total (100%) reduction for CC samples. Data from TN HTs indicate MBC was significantly lower for BB and BT samples (204 and 201 mg C/kg soil, respectively) compared to all other samples (overall average 289 mg C/kg soil). Although not statistically significant, Nmin and beta-glucosidase activity were lower in TN-HT SB, BB and BT (average 2.7ppm NH4+/7d and 50.5mg PNP/g soil, respectively) compared to CC and NM (average 3.6ppm NH4+/7d and 66.4 mg PNP/g soil, respectively). Further testing of BDM pieces may determine if physical and chemical alterations during field incubation contribute to microbial changes. Samples from TX and WA are pending, and will provide insight regarding degradation and changes in soil properties under different climate and soil conditions.
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