Sustainability of a Short-Rotation Woody Biofuel System Compared to Grass Biofuel and Grain Cropping Systems

Sustainability of a Short-Rotation Woody Biofuel System Compared to Grass Biofuel and Grain Cropping Systems

Summary

Establishment of a short-rotation woody biofuel system on upland claypan soils is not feasible under the sustained severe drought conditions recently experienced in the Midwest. However, native varieties of switchgrass are capable of survival and good growth under these conditions. In addition, early success of miscanthus in unrelated experiments suggests that the grass replace willow in the current project.

Objectives/Performance Targets

Expected outputs for the first year will be:
• Provide project information through traditional newsletters, such as MU Forestry’s Green Horizons quarterly publication, and local newspapers.
• Provide project information through two eXtension Communities of Practice (CoP): Wood Energy and Farm Energy
• Host a fall workshops on ‘Establishment of Energy Crops’; A minimum of 10 educators (Extension, NRCS, MO Department of Conservation, high school agricultural education instructors, etc) and 20 farmers will
attend.

Accomplishments/Milestones

For this research project in Centralia, MO the establishment of a short-rotation willow biofuel cropping system for the 2011 and 2012 growing seasons has been greatly frustrated. The primary cause frustrating establishment has been the severe drought (Figs 1 and 2). On April 5th, 2011 ~13,000 cuttings (~25 cm in length) were planted by hand on three 0.85 acre plots. Planting was ideal and by early June assessments were that > 90% of the cuttings produced growing plants (Fig 3). Early-season weed control seemed to sufficient. However, dry and hot conditions late in the summer resulted in death for about 40% of the plants. Surviving plants ranged from poor to good condition. Replacement cuttings (~50 cm in length) were order
from Dr. Tim Volk at the State University of New York- Syracuse and replanted in early April, 2012. Again, planting conditions were ideal with cuttings being pushed into moist soil. Weed control continued with targeted spraying using glyphosate and mowing. The heat and dry conditions in 2012 were more extreme than in 2011. By the end of the summer all but a few of the replants from that spring were dead, and an additional 20% of the first year’s plantings had also died (Fig 4). This left at the end of the second growing season only 35-40% of plants alive. The condition of these plants ranged from poor to good, but with minimal wood growth from the 2012 growing season.

Though these two particular growing seasons were especially difficult in establishing the willow crop, the consensus of the research team was that the droughty nature of upland claypan soils will make it extremely difficult to establish a viable short-rotation willow biofuel cropping system. Input from the farmer Advisory Board supported this conclusion. They suggested farmers will be reluctant in attempting this system for these soils given the outcome of this project. Given this conclusion, alternative bioenergy crops were considered in Oct/Nov 2012 as a replacement for the willow cropping system.

In 2011 USDA approved millions of dollars to stimulate bioenergy production through the BCAP. Three projects were approved through MFA Oil Biomass (Columbia, MO) to assist farmers in central and southwest Missouri and in northeast Arkansas for growing miscanthus as a bioenergy crop. Farmers enrolled ~13,000 acres for 2012 planting. About 10 BCAP miscanthus fields are within 10 miles and on similar claypan soils as the Centralia, MO research site. While bioenergy crops have been evaluated extensively on more productive soils, little is known about their yield performance and their impact on and water quality.

Requested input from technical and program staff with the Missouri NRCS resulted in the following recommendation: “BCAP has targeted Miscanthus to a substantial acreage in the surrounding counties of the ARS site in Centralia. Researchers at the NRCS Plant Materials Center in Elsberry are studying plant attributes such as growth curves, residue litter, biomass production and erosion protection of Giant Miscanthus for RUSLE ll. Scientists have been surprised by the ability of first-year plantings to persist during the severe drought of 2012. We need to understand water usage by the plant in a long rotation and also what changes are occurring to the soil quality, organic matter, infiltration, rooting depths when this species is harvested for a biofuel crop in the dormant stage over a long rotation. The ARS Centralia site is a good location for this Miscanthus data collection. Since the USDA has targeted Missouri for growing Miscanthus, more is need to be known about the positives and negatives of this species in the area in regards to soil and water resources.”

Given this need for better science on miscanthus, the relevance to the USDA BCAP program, and the willingness of MFA Oil Biomass to provide the miscanthus rhizomes and help plant at the research site, we propose miscanthus replace the willow cropping system. As such we propose the grant be amended to help support the evaluation of this cropping system. The other four cropping systems identified in the proposal (3 grain cropping systems and switchgrass) will continue as previously described.

• Fig 1. The precipitation for the research site gives a 39-yr average (1971-2010) cumulatively by day over the entire year along with the last three years. The black box highlights the precipitation during the growing season.
• Fig 3. 2011 willow establishment was good. Image from early May.
• Fig 2. Growing Degree Days (GDD) are measured by adding the high temperature and the low temperature together, dividing by two, and subtracting the minimum temperature needed for growth. The black box highlights the GDD during the growing season.
• Fig 4. Summer 2012; Willows dying from heat/drought stress, but weeds thrived!

Impacts and Contributions/Outcomes

Farmers and educators will increase their knowledge of the soil-enhancing benefits of producing dedicated energy crops on marginal claypan soils, and they will learn how to produce these crops. Early-adopter farmers will use the information to establish sustainable supplies of biomass that will support established bioenergy markets in mid-Missouri, such as the University of Missouri Energy Plant in Columbia or Show- Me Energy in Centerview, Missouri. The less intensive management in producing energy crops compared to conventional grain cropping systems will reduce soil erosion and improve soil quality.

Collaborators: