Effect of continuous overlay mulching of rice straw-plastic film on control of invasive plant Bidens pilosa L.

The invasive plant, Bidens pilosa L., has extensively damaged the agricultural, forestry, and animal husbandry industries in China. Combining rice straw and plastic film mulching may be an ecological and efficient control method and was investigated in this study. Three straw mulching amounts (0 kg·m^-2, 1 kg·m^-2, and 1.5 kg·m^-2) were used, which was performed during winter followed by overlaid film mulching in spring. The environmental indicators (i.e., soil temperature, soil relative water content, surface air temperature, and relative humidity) and community indicators (i.e., weed biomass, seed germination amount, weed community structure, and soil seed bank) were measured in the middle periods both of straw mulching and film mulching. The results showed that rice straw mulching in winter significantly reduced the midday soil temperature, surface air temperature, B. pilosa L. biomass, seed germination amount, the dominant weed species coverage, and the number of subordinate weed species. The 1.5 kg·m^-2 treatment had the greatest effect. When film mulch was overlaid in spring, the temperatures of the shallow soil and surface air all increased, the humidity of shallow soil decreased, while the surface air humidity increased. The seed density of B. pilosa L. in 0-5 cm soil layer mulched by film was significantly decreased by 79.49% compared to non-film mulched. Overlaid film mulching after rice straw mulching, all B. pilosa L. died, and no seeds germinated. Rice straw mulching in winter followed by film mulching in spring can effectively prevent and control B. pilosa L. growth. This study provides an alternative method to prevent and control the spread of invasive weed species in different seasons.