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Polyethylene mulch use is common in vegetable production, but disposal of mulch is problematic for growers and of significant environmental concern. Biodegradable fabrics and plastic films are compostable and can be incorporated into the soil at the end of the growing season, but questions remain about the durability, performance, and rate of decomposition of these products after soil incorporation. Three trials were conducted in field and high tunnel cucumber (Cucumis sativus) cropping systems to compare performance and decomposition after use among two bioplastic films and four experimental spunbond, nonwoven biofabrics. Soil temperature and moisture, mulch durability and deterioration, weed suppression, and crop yield data were collected in each growing season. All biomulches were soil incorporated after the growing season and recovered up to 11 months after incorporation to estimate relative rates of decomposition. One bioplastic film increased field soil temperature by 2 °C in 2013, but temperatures under the biofabrics were not different from bare soil. Bioplastics and biofabrics increased soil moisture relative to bare soil. Bioplastic films were less durable and deteriorated sooner than biofabrics, especially in the field environment (as early as 34 days after transplanting). All biomulches suppressed weed emergence relative to bare soil, but weeds were visibly growing beneath the most translucent biofabric. Marketable yield of cucumber was trending highest in the most durable and opaque biofabric (1827 g·m−2), but was not significantly different from weed-free bare soil (1251 g·m−2). Relative rate of mulch decomposition up to 11 months after soil incorporation was not different among bioplastic and biofabric products. Results suggest that the tested biofabrics will be most useful to growers when soil warming is not necessary (e.g., warm climates), but moisture conservation and weed control are critical (e.g., organic cropping systems). Moreover, biofabrics are permeable and may be useful to growers dependent on sprinkler irrigation or rainfall to meet crop water demands.

Biobased and biodegradable mulches (BDM) are a potentially sustainable alternative to polyethylene plastic mulch because they can be tilled into the soil at the end of the growing season. However, their degradation rate in the soil is uncertain, limiting their on-farm adoption. The objective of this study was to determine whether organic soil management practices could be leveraged to speed degradation of two potentially BDM across two diverse agroecoregions [Lincoln (LNK) and Scottsbluff (SBF), NE, USA]. Management treatments included compost, compost extract, cover crops, all three of these practices combined and a control. The two mulch types studied were a nonwoven polylactic acid fabric with embedded wood particles (PLA), and a starch-polyester mulch film (BLK). Mulches were applied in spring 2017 for vegetable production and removed in fall after harvest. Recovered mulch was sectioned into squares 10 cm2 and buried in mesh bags for 22 months. Mulch degradation, and soil chemical, physical and biological properties were measured at four times over 2 years. Management treatments applied seasonally across 2 years led to expected changes in soil properties, yet they had no effect on mulch degradation. Instead, mulch degradation was driven by the interaction of location and mulch type. The BLK mulch had degraded by 98% at LNK after 12 months, but only by half after 22 months at SBF. Degradation of PLA after 22 months was similar between locations with 29 ± 4% mulch mass remaining at SBF and 33 ± 4% remaining at LNK. Climate and soil characteristics at each location were strong determinants of mulch degradation. Specifically, soils at LNK were finer textured, lower in pH, higher in soil water content, organic matter and nitrates, and with greater bacterial abundance compared to SBF. The strong location by mulch type interaction observed could inform the development of regionally specific predictive models of degradation.

Manufactured biobased mulch (biomulch) films and fabrics are useful non-chemical weed management tools, but are not typically used for high-density plantings of vegetables such as lettuce (Lactuca sativa L.) and carrot (Daucus carota L. subsp. sativus). However, it may be possible for crop roots to grow through a permeable biomulch membrane. Our objective was to demonstrate the potential for lettuce and carrot to germinate on and grow through biomulch, and assess changes in crop growth and yield. Biomulches included a 100% polylactic acid (PLA) biofabric and a PLA (37%) + soybean meal (63%) biofabric (PLA + SOY). Seeds were placed directly on biomulch and top-dressed with a soil mix or compost. Crop roots grew through the biomulch (despite visible constriction in carrot), and total yields were either the same or greater than those in the no-mulch control. PLA + SOY increased lettuce yield by 72% and also degraded faster than the PLA mulch. Results hold promise for improving weed control and reducing labor in high-density vegetable plantings.