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

Project Overview

LNC11-337
Project Type: Research and Education
Funds awarded in 2011: $198,321.00
Projected End Date: 12/31/2015
Region: North Central
State: Missouri
Project Coordinator:
Dr. Hank Stelzer
University of Missouri

Annual Reports

Commodities

  • Additional Plants: native plants, trees

Practices

  • Crop Production: agroforestry, forestry
  • Education and Training: demonstration, extension, farmer to farmer, mentoring, networking, participatory research, workshop, youth education
  • Energy: bioenergy and biofuels
  • Farm Business Management: new enterprise development, agricultural finance
  • Natural Resources/Environment: carbon sequestration, afforestation, soil stabilization
  • Soil Management: soil microbiology, organic matter, soil physics, soil quality/health
  • Sustainable Communities: new business opportunities

    Abstract:

    A comparison of a short-rotation willow and grass biofuel crops to grain crops on marginal, claypan soils was conducted. Willow establishment failed as a result of the extreme heat/drought conditions of 2011 and 2012, and was replaced with miscanthus. Miscanathus establishment was good regardless of landscape position, rhizomes > 18 g produced more biomass, and nitrogen fertilization did not generally improve first- or second-year yield. Switchgrass yield in 2013 and 2014 ranged from five to six tons/acre; comparable with similar claypan studies. Baseline soil and water quality has been obtained, with instrumentation upgrades to aid future studies.

    Introduction:

    Marginal soils, like many claypan and claypan-like soil areas of the North Central Region, are disproportionate sources for non-point pollution and soil quality degradation when used for grain production. In the North Central Region, these two Major Land Resource Areas occupy over 11 million acres and are generally defined as being highly erodible and having average to poor grain crop yield. The high erosion rates of these soils have caused many field areas to lose 30 to 90 percent of their topsoil as a result of cultivation practices over the last 150 years. These marginal soils from a grain production standpoint also contribute the most to environmental concerns, such as additional erosion and nutrient losses from fields. Alternative production systems are needed for long-term productivity and environmental sustainability. Woody biomass plantations could help address those concerns.

    The resulting fiber from woody biomass plantations could also be a feedstock source for emerging bioenergy markets. For example, in 2013 the University of Missouri’s (MU) Energy Plant installed a biomass boiler creating a market for 100,000 green tons of wood chips annually. While the initial plan calls for the energy plant to utilize sawmill residues, MU is interested in developing long-term supply contracts with farmers capable of growing dedicated wood energy crops to offset reduced mill residues during a poor economy. This demand for biomass created an opportunity to: (1) evaluate the potential positive effects that woody energy crops can have on improving soil and water quality, and soil structure on marginal upland sites, and (2) demonstrate the potential these energy crops have for improving farm profitability.

    The woody energy crop initially proposed in this research was short-rotation willow. Establishment of the willow on claypan soil research site was greatly frustrated by the extreme heat and drought summers experienced during the first two years of this study (2011 and 2012). After extensive discussions, the consensus of the research team was the droughty nature of upland claypan soils would make it extremely difficult to establish a viable short-rotation willow biofuel cropping system. Input from the farmer Advisory Board supported this conclusion. Given this conclusion, alternative bioenergy crops were considered and miscanthus was selected as a replacement. Miscanthus was chosen primarily because some of the first production acres in the US were planted in the Central Missouri region in the spring of 2012 as a part of the USDA BCAP project. USDA NRCS supported miscanthus as the replacement crop for this study because very little was known about miscanthus production and impact on water use, runoff and water quality, and soil health. After consultation with North Central Region SARE program staff, a formal request altering the willow energy crop to miscanthus was made and approved in the spring of 2013.

    Literature Review

    The agriculture industry is faced with increasing demands for food, feed, and energy, dwindling available resources in energy and land, and increasing productivity uncertainty due to climatic variability. We propose to address these challenges for marginal Midwest soils, where grain cropping over the past 150 years has accelerated erosion and severely degraded cropland productivity (Lerch et al., 2007; Massey et al., 2008). With the prospect of emerging bioenergy feedstock crops, degraded soil landscapes will likely be prime candidates for perennial bioenergy feedstock crop production that would allow for restoration of ecosystem services. A review of the SARE database revealed no similar projects designed to address the problem stated in our proposal.

    Marginal Claypan Soils

    The Midwestern U.S. claypan region encompasses an area of about 10 million acres within Missouri, Illinois, and Kansas (Jamison et al., 1968; Anderson et al., 1990). In Missouri, claypan soils are predominant in the North-East quadrant of the state and are the major soils of the Salt River Basin feeding into the Mark Twain Reservoir. These soils are characterized by a subsoil horizon with an abrupt and large increase in clay content compared to the overlying materials occurring within a short vertical distance in the soil profile (Soil Science Society of America, 2001). The claypan occurs at depths varying from 0.3 to 1.6 ft with clay content ranging from 35 to 65% (Miles and Hammer, 1989; Blanco-Canqui et al., 2002; USDA-NRCS, 2006). Claypan soils are usually classified as somewhat poorly to poorly drained and have slow to very slow permeability. The low saturated hydraulic conductivity of the claypan perches water creating a high probability of runoff in most years during the winter and spring periods (Blanco-Canqui et al., 2002) and during wetter-than-average summer growing seasons.

    Plant-Available Water and Claypan Soil Production

    Crop growth in response to soil available water as affected by cropping systems can be difficult to characterize because of highly variable soil and landscape properties, such as surface run-on and run-off, subsurface water redistribution, soil horizon distributions, and organic matter. Particularly problematic are the claypan soils since profile water storage is generally low, limiting crop production in most average to dry precipitation years. Water storage is especially reduced in eroded areas with shallow topsoil (Jiang et al., 2008). In consequence, this property of topsoil depth is a dominant factor in grain yield variability within fields (Kitchen et al., 2005). High clay content at or near the soil surface of these soils also limits grain yield due to poor germination, reduced infiltration, and poor soil moisture recharge. Yield within these fields often varies as much as 4:1 from high- to low-yielding areas.

    In the last 15 years grain yield monitoring, which records grain yield point-by-point during field harvesting, has revolutionized farmers’ ability to quantify field productivity. Along with helping to understand specific management decisions (e.g., variety, variable fertilizer application), yield monitoring has elucidated the impact of landscape properties (Fraisse et al., 2001; Kravchenko and Bullock, 2000) and the lost productivity with eroded topsoil (Kitchen et al., 1998). Initial work using yield maps from Northeast Missouri showed that the acres of economically marginal soils currently in grain production may be larger than previously thought (Massey et al., 2005), because profitability has traditionally been calculated on a whole field or whole farm basis. One exercise from this study took 10 years of corn and soybean yield maps from an 88 acre claypan soil field and converted them to profitability maps. They found that on average 25 percent of the field cost more to farm than the grain revenue generated from those areas. Their conclusion was less risky crop production systems are needed for such claypan soil fields.

    Landscape Linkages between Productivity and Ecosystem Function

    Farmers want to be good stewards of the land they manage (Murphy et al., 2010). However, given the economic constraints they are subjected to, it often takes personal observation to trigger a change in practices (Murphy et al., 2010, Wright-Morton et al., 2007). Thus, where there is evidence of degradation that decreases productivity, e.g. erosion rills or frequent flooding from a nearby stream, practices are put in place to remedy the problem. These practices are subsidized by USDA because they also improve environmental stewardship and thus benefit everyone. In some areas, erosion control measures will be implemented, in others riparian buffers will be established. However, when the problem is gradual (i.e., due to 100 years of cultivation) and invisible (e.g., soil degradation, chemical runoff), there is no visual evidence and thus no likely remedy undertaken.

    Research investigating the links between ecosystem function and productivity is limited. Perhaps the most relevant work is from Mudgal (2010) who used the APEX model to show that, if the backslope portions of a claypan soil field still had original soil properties (i.e. as they were before agricultural production for 100 years caused soil degradation), runoff and atrazine loss from these areas would be significantly lower and corn and soybean yields would be significantly higher.

    Cellulosic Biofuel Crops as an Alternative to Grain Cropping

    Because grain yield on marginal claypan soils is vulnerable to both drought (average to dry years) and excess wetness (wet years) due to the presence of this heavy-clay subsoil, risk is high with regard to grain crop profitability. For this reason, marginally productive soils in this region are prime candidates for conversion from grain crops to grass production for biomass energy and soil and water conservation. Upland claypan soils in Northeastern Missouri are well suited for perennial plants such as willows and warm season grasses. Prior to settlement, these areas supported water-use-efficient native warm season grasses and some woody species in localized upland locations and along streams and rivers (Lerch et al., 2007). Perennial grasses such as those used for biofuel crops often improve physical soil properties (e.g., bulk density, water infiltration, aggregate stability) compared to annual crops such as corn or soybean (Jiang et al., 2007; Blanquo-Canqui, 2010). In addition, the water demand from biofuel crops is higher earlier in the season and chemical inputs are lower than for grain crops, thus potentially delaying generation of runoff and soil erosion, and reducing pollutant transport (Schilling et al., 2008). Consequently, it is likely that introducing perennial bioenergy crops in the agricultural landscape would lead to improved water quality. Preliminary results confirmed this trend for small field size watersheds in Iowa (Liebman et al., 2010). Researchers using the APEX model showed that planting perennial grasses on the backslope of a 35 ha field reduced sediment and nutrient loadings (Mudgal, 2010).

    Integration of modern bioenergy production into current cropping systems presents new soil management challenges, and opportunities. Our current limited knowledge of production demands of biofuel crops is inadequate to predict the ecological impacts of these crops on soil processes. Bioenergy production is now beginning to involve cellulosic biofuels in addition to grain bioethanol/biodiesel (Blum et al., 2010). Regardless of which bioenergy system is used, guidelines for BMPs will be necessary to sustain or improve soil quality and acceptable soil productivity (Blanco-Canqui, 2010; Johnson et al., 2007; Wilhelm et al., 2004). Biomass harvest has potential to impact soil nutrient dynamics, water relations, and other important soil processes. The strong linkage of above-ground and below-ground biodiversity (Wardle, 1995; Grayston et al., 1998) suggests that mixed perennial grasses and fast-growing woody species managed for biofuel production may be more beneficial than annual crop monocultures for maintaining diversity of soil microorganisms and overall soil quality, and may also be more resilient to climate change than grain crops because of perennialization.

    Very little research on soil quality in the context of biofuel production has been conducted (Blanco-Canqui, 2010). Existing information focuses primarily on the response of soil organic C, considered the key soil quality indicator (Johnson et al., 2006), to residue management in annual crops and to growth of perennial crops in undisturbed soils. Soil C under switchgrass as a biofuel crop increased by 10 Mg ha-1 yr-1 within a 3 ft soil depth in temperate climates (Garten and Wullschleger, 1999). Current research at USDA-ARS, Mandan, ND demonstrated variable changes in soil C under switchgrass five years after establishment (Liebig et al., 2008). Even less is known about effects of woody biofuel species other than increased soil C accumulation and N mineralization under short rotation coppice plantations of willow compared with cultivated fields (Blum et al., 2010; Jug et al., 1999). However, conversion of grassland to short-rotation forestry plantations tends to accelerate initial soil C and N losses before recovering to original or increased levels after trees become established (Jug et al., 1999).

    Woody Biomass Systems

    Woody crops have advantages as a feedstock for bioenergy. Generally, the woody material is a consistent energy source (Miles et al., 1996) and has low mineral ash. They have the advantage of flexibility in harvest times that grain crops do not have. Production inputs (e.g., fertilizers and herbicides) for managing the woody crops are much reduced from what is necessary for grain crops. Finally, woody biomass net energy ratios are greater than many other feedstocks for biofuels, usually in the 10-20:1 range (Keolian and Volk, 2005), thus considerably more energy is produced per unit fossil fuel used from woody feedstock crops. This net energy ratio will become an increasingly significant factor as advanced liquid fuel production technologies mature. Shrub willow (Salix spp.) crops are an example of a production system that has shown promise as a biomass crop in the United States in recent decades (Volk et al., 2006). It has been grown successfully on marginal agricultural lands in much of the eastern half of the U.S. (Appendix 9). Trials have demonstrated yields of three to five tons per year for the first rotation (Volk and Luzadis 2009), and 20 to 50 percent more than that for secondary rotations. Recent studies at the University of Minnesota (Thelemann et al, 2010) have indicated that landscape position may affect the productivity of willow, cottonwood (Populus deltoides), and hybrid poplar (Populus maximowiczii x P. nigra), suggesting that further research needs to be conducted.

    Energy Balance of Perennials

    Perennial woody species and grasses for biomass energy are desirable over grain-based biofuels since the latter have been projected to be a net producer of greenhouse gasses (Lewandowshi et al, 2003). The carbon balance of biofuel production on marginal soils is less compared to high yielding soils. In contrast to biofuel production, perennial grasses sequester atmospheric carbon due to their extensive perennial root systems. The energy balance of ethanol and biodiesel production is also less positive for marginal soils than for prime farmland. A similar amount of equipment, fuel and chemicals are used on both, while the yield of grain is depressed on marginal soils. It follows that using marginal soils for grain biofuel production may result in a loss of energy (or net negative energy) because of depressed yields when growing conditions are not ideal. However, the energy balance of warm season grass biomass production is several times more positive than that of grain (Tilman et al., 2006). Thus, for the goals of maximizing energy production and sequestering carbon, biomass is a better solution on marginal soils.

    Literature Cited

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    Blanco-Canqui, H., C.J. Gantzer, S.H. Anderson, E.E. Alberts, and F. Ghidey. 2002. Saturated hydraulic conductivity and its impact on simulated runoff for claypan soils. Soil Sci. Soc. Am. J. 66:1596-1602.

    Blum, W.E.H., M.H. Gerzabek, K. Hackländer, R. Horn, R. Reimoser, W. Winiwarter, S. Zechmeister-Boltenstern, and F. Zehetner. 2010. Ecological consequences of biofuels. p. 63-92. In R. Lal and B.A. Stewart (ed.) Soil Quality and Biofuel Production. CRC Press, Boca Raton, FL.

    Fraisse, C.W., K.A. Sudduth, and N.R. Kitchen. 2001. Delineation of site-specific management zones by unsupervised classification of topographic attributes and soil electrical conductivity. Trans. ASAE 44(1):155-166.

    Garten, C. T. and S.D. Wullschleger. 1999. Soil carbon inventories under a bioenergy crop (switchgrass): measurement limitations. J. Environ. Qual. 28:1359–1365.

    Ghidey, F., Blanchard, P.E., Lerch, R.N., Kitchen, N.R., Alberts, E.E., Sadler, E.J. Measurement and prediction of herbicide transport from the corn phase of three cropping systems. J. Soil Water Cons. 60(5): 260 273. 2005.

    Grayston, S.J., S.Q. Wang, C.D. Campbell, and A.C. Edwards. 1998. Selective influence of plant species on microbial diversity in the rhizosphere. Soil Biol. Biochem. 30:369-378.

    Jamison, V.C., D.D. Smith, and J.F. Thornton. 1968. Soil and water research on a claypan soil. USDA Tech. Bull. 1379. U.S. Gov. Print. Office, Washington, DC.
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    Jiang, P., Kitchen, N.R., Anderson, S.H., Sudduth, K.A., Sadler, E.J. 2008. Estimating plant-available water using the simple inverse yield model for claypan landscapes. Agronomy Journal. 100:830-836.

    Jiang, P., S.H. Anderson, N.R. Kitchen, E.J. Sadler, and K.A. Sudduth. 2007. Landscape and conservation management effects on hydraulic properties of a claypan-soil toposequence. Soil Sci. Soc. Am. J. 71(3): 803-811.

    Johnson J.M.F., R.R. Allmaras, and D.C. Reicosky. 2006. Estimating source carbon from crop residues, roots and rhizodeposits using the national grain-yield database. Agron. J. 98:622-636.

    Johnson, J.M.F., M.D. Coleman, R. Gesch, A. Jaradat, R. Mitchell, D. Reicosky, W. W. Wilhelm. 2007. Biomass-bioenergy crops in the United States: A changing paradigm. Am. J. Plant Sci. Biotechnol. 1:1-28.

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    Lerch, R.N., E.J. Sadler, N.R. Kitchen, K.A. Sudduth, R.J. Kremer, D.B. Myers, C Baffaut, S.H. Anderson, , and C.H. Lin. 2007. Overview of the Mark Twain Lake/Salt River Basin conservation effects assessment project J. Soil Water Cons. 63(6):345-359.

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    Objectives / Performance Targets

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    Volk, T.A., L.P. Abrahamson, C.A.Nowak, L.B.Smart, P.J. Tharakan, and E.H. White. 2006. The development of short-rotation willow in the northeastern United States for bioenergy and bioproducts, agroforestry and phytoremediation. Biomass & Bioenergy, 30: 715-27.

    Volk, T.A. and V. Luzadis. 2009. Willow biomass production for bioenergy, biofuels and bioproducts in New York. In Renewable Energy from Forest Resources in the United States. Routledge Press, New York, NY. pp 238 – 260.

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    Project objectives:

    The overarching objectives of this project were to: (1) evaluate the potential positive effects that woody energy crops (later miscanthus) could have on improving soil and water quality, and soil structure on marginal upland sites, and (2) demonstrate the potential these energy crops have for improving farm profitability. As such the project sought to simultaneously demonstrate that farmers could improve crop profitability and soil and water quality by replacing under-performing grain crops growing on marginal cropland with better-performing, low-input, grass and short-rotation woody (or miscanthus) biomass plantings. The project took an integrated approach to dedicated energy crop development combining environmental and production research with outreach efforts designed for both farmers and educators. The goal was to afford farmers and educators the opportunity to observe all phases of producing energy crops (e.g. establishment, growth and development, and harvesting), as well as comparing production inputs/outputs to conventional grain cropping systems. More importantly, soil and water data from the replicated plots would enable researchers to assess the environmental sustainability of growing dedicated energy crops. The project was viewed to be long-term in nature with this SARE R&E Grant providing the initial funding. It was hoped these findings would lead to additional competitive funding.

    Expected outputs: (1) two, peer-reviewed manuscripts evaluating quantitative yield data and/or nutrient, herbicide, sediment, and runoff volume among the cropping systems; (2) project press releases through newsletters, local newspapers, and eXtension; (3) MU Guide Sheets on growing willow or miscanthus for bioenergy; and (3) fall workshops, one at the end of each year of the project, for educators (Extension, NRCS, MO Department of Conservation, high school agricultural education instructors, etc) and farmers.

    Upon attending a workshop, the educator was to share their knowledge with farmers and other agricultural educators in their region. This could have been through face-to-face workshops or distance-learning webinars. The expectation was for a minimum of ten farmers or agricultural educators to attend each event offered. Upon attending a workshop, at least six Mid-Missouri farmers within 50 miles of an established bioenergy facility would begin establishing dedicated energy crops.

    Short-term outcomes: (1) Farmers and educators would increase their knowledge of the soil-enhancing benefits of producing dedicated energy crops on marginal claypan soils; (2) Farmers and educators would learn how to produce these crops.

    Intermediate outcomes: (1) Early-adopter farmers would use the information they learned to establish sustainable supplies of biomass to support established bioenergy markets in mid-Missouri, such as the University of Missouri Energy Plant in Columbia and Show-Me Energy in Centerview, Missouri; (2) The less intensive management in producing energy crops compared to conventional grain cropping systems would reduce soil erosion; and (3) Educators would disseminate their expanded knowledge of producing dedicated energy crops in their region of influence.

    Long-term outcomes: (3) Farmers growing energy crops on marginal claypan soils would reduce their production input costs compared to conventional grain cropping systems thereby increasing their profitability; (2) Soil organic matter and soil structure would be improved over time as a result of leaving plant root systems in the soil; and (3) The expanded growth and development of the supply chain involved in producing, harvesting, and transporting bioenergy crops to bioenergy facilities would provide stable jobs and enhance the quality of life in rural communities.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.