Differences in soil and habitat conditions, depending on the type of soil on which shrubby species of willow Salix L. are being grown for energy purposes, are reflected in weed infestation species diversity and the distinctiveness of these crops, and require an individual program of control and reduction of the abundance of competitive herbaceous vegetation. Our study aimed at determining soil parameters that have the greatest effect on weed infestation structure in a plantation of basket willow (Salix L.) coppice. The following chemical soil properties were taken into account as environmental variables: soil pH, soil moisture content, and humus, total nitrogen, potassium, and phosphorus content. Field research was carried out at five plantations of fast-growing basket willow (Salix viminalis L.) hybrids of the genotypes jorr, sprint, and turbo situated on disposal sites of sandy silts and sewage sludge-fertilized silts as well as fallow post-farmland and grassland. Obtained research results indicate soil reaction and soil moisture as factors that have the biggest effect on diversity of competitive herbaceous vegetation accompanying energy willow coppices.