Evaluating Biodegradable Mulches in Diverse Climates in the U.S

In a recent study, deterioration, weed control, and tomato yield were evaluated for three commercially available mulches marketed as biodegradable (BioBag, BioTelo, WeedGuardPlus), an experimental spunbond poly (lactic acid) mulch (SB-PLA), and black plastic mulch. This study occurred in three climatically diverse regions of the U.S.: the subtropical southeast, with a hot and humid summer climate (Knoxville, TN); the High Plains south, with a hot and dry summer climate (Lubbock, TX); and the Pacific Northwest, with a cool, humid summer climate (Mount Vernon, WA). The test crop was tomato grown in both open field and high tunnel production systems. In all three locations, mulch deterioration (measured visually) was greater in the open field  when compared to the high tunnels—likely due to increased moisture, solar radiation, and wind (with associated blowing abrasive soil particles) in open field environments. Mulch deterioration was greatest for the commercially-advertised biodegradable mulches. Weed pressure was greatest under the experimental SB-PLA-10 mulch—likely due to the opaque nature of the fabric, which favored weed seed germination. The SB-PLA-10 was reformulated and recolored to alleviate this problem. Tomato yields were improved with mulch treatments when compared to bare ground in Knoxville and Mount Vernon, whereas in Lubbock, bare ground and spunbond fabric tended to have the highest tomato yield—likely due to the reduced soil temperatures in those plots.