Alternative methods of site preparation and coppice management during the establishment of short-rotation woody crops.

摘要

Short-rotation woody crops (SRWC) are being developed as a sustainable system that simultaneously produces a renewable feedstock for bioenergy and bioproducts and a suite of environmental and rural development benefits. The establishment phase is critical to the economic and biological success of SRWC. Current site preparation recommendations include a combination of mechanical and chemical weed control, which results in limited vegetation cover and increases the potential for soil erosion. To capitalize on the increased growth rates of coppice regrowth, coppicing during the dormant season after the first year of growth has been the standard recommendation. These experiments examined the effects of coppicing and different site preparation practices on SRWC biomass production and other plant and soil characteristics.; In the first experiment, coppicing or not coppicing after the first year of growth had no effect on aboveground or root biomass, or root:shoot ratios during the first rotation, but these characteristics varied among clones and sites. Poplar (NM6) production was 6.8–13.8 odt ha−1 yr−1 while willow (SV1) ranged from 3.8 to 10.5 odt ha−1 yr−1.; In the second experiment, poplar and willow biomass production in spring tillage and cover crop site preparation treatments was similar to or greater than the currently recommended fall tillage approach. Strip tillage was also effective for poplar. Poplar production was greater than 12 odt ha −1 yr−1 for these treatments while willow production ranged from 5 to 8 odt ha−1 yr−1 . Soil carbon levels increased by 12 to 24 Mg ha−1 in the 15–30 cm layer in some treatments and did not change in the top 0–15 cm over three years.; Incorporating cover crops during the establishment phase requires assessing three factors, aboveground biomass production, weed control, and residue cover. In the third experiment, winter rye cover crops were planted in the fall and killed by one of three methods in the spring. The use of cover crops increased biomass production of poplar by 85% and had no effect on willow production. Production was greatest, weed cover was the lowest, and residue cover was highest when the rye was killed with a postemergence herbicide in the spring just prior to planting.