Development of agroforest systems for bioenergy crop production and ecosystem services in the lower Mississippi Alluvial Valley

Development of agroforest systems for bioenergy crop production and ecosystem services in the lower Mississippi Alluvial Valley

Summary

The purpose of this project is to develop economically viable agroforest systems for producing cellulosic bioenergy crops that will also enhance ecosystem services in the Lower Mississippi Alluvial Valley. The project focuses on determining the amount and quality of biofuels that can be produced by cottonwood and switchgrass grown in agroforest systems; assessing the effects of these crops on carbon sequestration, small mammal populations/habitat, and water quality; and providing information on these systems to landowners and natural resource professionals. Work to date has concentrated on establishing the cropping systems, conducting initial outreach efforts, and monitoring initial results from the project.

Objectives/Performance Targets

The objectives of this project are to:

1. 1. Quantify biomass production, potential bioenergy (ethanol, syndiesel, etc.) yields, and economics of agroforest systems with a variety of cottonwood and switchgrass compositions.
   2. Quantify ecosystem services (carbon sequestration, nitrogen retention, wildlife habitat, and biodiversity) provided by agroforest systems with a variety of cottonwood and switchgrass compositions.
   3. Provide information to farmers, bioenergy industry professionals, county agents, natural resource managers, and regional public officials on the production potential, financial viability, and ecological impacts of cottonwood/switchgrass agroforest biofeedstock systems; demonstrate establishment, harvesting, and bioenergy conversion technologies appropriate to these agroforest systems; and establish a stakeholder research and outreach steering committees to direct current and future project activities concerning these cropping systems.

Accomplishments/Milestones

The first harvesting of switchgrass occurred in 2010 (2nd growing season) at two of the study sites. A harvest inventory indicated that 1.9-2.0 dry tons/acre was harvested at one site while 1.1-1.5 dry tons/acre was harvested at the other site. Average switchgrass density (crowns/square oot) was greater at the site (2.3-2.7) with the highest production and least at the site (1.4-1.8) with the lowest production. These densities are adequate for optimal production if the crowns are evenly distributed throughout the field or plot. However, in some areas of the study, adequate crown coverage did not exist. This may be related to the variation in soil depth, texture, moisture conditions, etc. inherent with these marginal soils. Carbon analysis of the harvested switchgrass has not been completed to date.

Adequate switchgrass establishment has not occurred at the third site. The soil at this site is heavy clay and has proven difficult for switchgrass establishment. It appears that the surface soil dries and develops a crust which retards the emergence of the weak switchgrass seedlings. Since switchgrass seed is small, it lacks the energy of other plant seedlings to break through this crust. To mitigate this crusting problem, we established winter wheat at this site in the areas that are to be planted to switchgrass in the fall of 2010. We applied herbicide in late winter (mid-March, 2011) to kill the winter wheat and form an organic layer on the soil surface. This layer will decrease soil drying, crusting, and thus improve switchgrass seedling emergence. The switchgrass will be drilled into the soil in mid-April. If this technique is successful, we will be able to provide a successful method for establishing switchgrass on these heavy clay soils.

Estimated aboveground cottonwood production during the first growing season (2009) ranged from 25 to 161 lbs/acre among the three sites. Total carbon in the aboveground portion of the cottonwood as measured during the dormant season was 11.6 to 74.4 lbs/acre. Several factors impacted cottonwood production in 2010. Precipitation at the three study sites was 60-70% of normal precipitation amounts. This appeared to reduce cottonwood production to a greater degree than switchgrass production. In addition, a cottonwood leaf beetle infestation occurred at one site during early summer. This beetle is a well-known cottonwood pest and was controlled by applying 8oz./acre of Provado® (imidacloprid, 1-[(6-Chloro-3-pyridinyl)methyl]-N-nitro-2-imidazolidinimine). There was not a serious decrease of tree growth as a result of this infestation. At another site herbicide damage of the cottonwood was observed. The damage appeared to be a result of the herbicide quinclorac ( 3,7-dichloro-8-quinolinecarboxylic acid). This herbicide is used in rice production and apparently the cottonwood damage was due to drift from nearby fields. This damage coupled with the lack of precipitation significantly reduced cottonwood growth at this site. Our recommendation to landowners is to avoid planting cottonwood adjacent to rice fields that utilize this herbicide. Current production estimates for the 2010 growing season have not been completed at this time.

Soybean grain and harvest residue production during the first growing season (2009) respectively averaged 793 and 1,795 lbs/acre at the three study site. One site had only minimal grain production due to stinkbug insect damage that was not detectable until harvest. Energy content of the residue averaged 13.38 million BTUs/acre at the three sites. The average amount of carbon sequestered in the aboveground portion of the soybean as measured during the harvest was 1,167 lbs/acre. Only 389.2 lbs/acre carbon and 73.8 lbs/acre of nitrogen was removed off site with this cropping system since only the grain was harvested and the residue was returned to the field. Grain sorghum yields (grain and residue) from the 2010 growing season have not been summarized to date.

Analysis of fuel quantity and quality will occur in 2012. Switchgrass samples, soybean samples (grain and residue), and cottonwood samples will be taken during the harvest season in 2011. Estimates of biomass for each crop will be made from harvested material or inventory data to determine the biomass production for each crop and cottonwood/switchgrass treatment combination. The fuel quality values from the sample analysis will be used with these biomass estimates to determine fuel production.

Initial soil sampling to a depth of approximately 12” was performed prior to crop establishment in 2009. Nitrogen contents averaged 1.2-2.2 tons/acre and carbon contents 13.3-20.2 tons/acre at the three sites. Soil sampling will occur at the end of the 2011 growing season to determine changes in soil carbon with the differing cropping systems.

Tension lysimeters were installed in the cottonwood, switchgrass, and soybean/grain sorghum cropping systems in late 2009. Initial soil water samples were collected in January-June of 2010 to equilibrate the lysimeters and establish sampling protocols. Analyses of these samples indicated the cropping history of the study sites had a larger impact on soil water chemistry than the establishment activities associated with the cottonwood and switchgrass cropping systems. Ion resin lysimeters were also installed within these cropping systems and information collected from this type of lysimeter was used to assess the quality of this method for determining nutrient fluxes that drain from these soils and crops.

Small mammal trapping at the study sites was conducted in July-August of 2010 and again in February of 2011. A total of 233 individuals and 5 species (marsh rice rat, Oryzomys palustris; white-footed mouse, Peromyscus leucopus; hispid cotton rat, Sigmodon hispidus; eastern wood rat, Neotoma floridana; and house mouse, Mus musculus) were captured in 2010. The largest number of rodents (96) was captured in the switchgrass cropping system and the smallest number (13) in the cottonwood cropping system. Captures in combined cottonwood/switchgrass agroforest were within this range.

In February 2011 a total of 98 individuals and 3 species (house mouse, hispid cotton rat, and white-footed mouse) were captured. The greatest number of individuals (63) was captured at the southeastern Arkansas site. The Louisiana site was the only location where all three species (house mouse, hispid cotton rat, and white-footed mouse) were captured.

To better understand space and habitat use by these small mammals, a subset of captured rodents were fitted with radio collars and tracked. During the summer 2010 sampling period, we found that some of our radio-collared animals were able to remove their collars by sliding them over their heads. The collar attachment method provided by the collar manufacturer (Advanced Telemetry Systems, ATS) was insufficient for secure attachment. Since 2010, we have worked closely with ATS to develop a radio-collar attachment method that would prevent, or at least significantly reduce, collar removal. We developed a new attachment method that uses plastic zip ties. This method will allow a collar to be more securely attached to an animal and thus increase the length of time that the locations of the collared animals can be tracked. During the February 2011 sampling period we captured only 1 cotton rat large enough (?50 g) to radio-collar. Although we are only beginning to test our new collar attachment method, we believe it will virtually eliminate dropped collars. Extensive testing of our collar attachment method will take place during the spring sampling period which will occur in late April and early May, 2011.

Advisory committees were formed for each site from landowners and agricultural professionals. Two of these committees have met twice and one has met once since their formation. These committees have helped review research and study methods as well as develop outreach activities at each site.

Two field days which focused on this project occurred in 2010. A “Bioenergy” field day occurred on August 2, 2010 at the central Arkansas study site. This field day was attended by approximately 70 landowners, foresters, farmers, and extension personnel. Attendees were introduced to the project, viewed current project activities in the field, and observed on farm thermal conversion of cellulose to liquid fuel. A field day at the Louisiana study site occurred on August 27, 2010 and was attended by 16 individuals. The project was also a component of an annual field day that occurred at the UA Research and Education Center operated at the southeastern Arkansas study site. Two additional educational programs are being planned for 2011. One will focus on harvesting biomass and the other will introduce county extension agents to bioenergy production and conversion methods.

A newsletter was developed to provide information concerning the project to interested landowners and public. This newsletter highlighted the initial objectives of the study, some of the initial methods used to establish the crops utilized in the project, and practical considerations for landowners who might be contemplating establishment of bioenergy crops (Document 1). The newsletter is disseminated to the advisory committee members as well as to field day, workshop, and meeting attendees. A fact sheet is currently in preparation which will provide information on establishment and management cottonwood for biomass and timber production.

• Document 1

Impacts and Contributions/Outcomes

This project has been a high profile project within the University of Arkansas and Louisiana State University Agriculture Center bioenergy efforts during the past year. Baseline information and support from this project was used to leverage additional funding from the Agriculture and Food Research Initiative Program administered by the USDA National Institute of Food and Agriculture to support the work on these bioenergy agroforest systems. This new funding will allow an additional four years of project activities to occur following the end of the SARE project and to provide more long-term results from these bioenergy agroforests.

This project has supported two graduate students. One student is comparing the different lysimeter methodologies for monitoring soil water chemistry at the research sites. The other student is determining small mammal population dynamics in relation to the different cropping systems.

Surveys distributed at field days indicated a waning interest in landowners planting switchgrass and cottonwood for energy production. With decreases in energy prices and a lack of markets for these products, only a small portion of farmers are willing to plant these crops. Individuals who currently manage forests for biomass production as a secondary product may have more of an interest in agroforest for bioenergy production than a broader spectrum of landowners.

Several presentations concerning the project and/or initial results of the project were presented at landowner or professional meetings. Below is a list these presentations.

• Liechty, H.O., Formby, K., and Blazier. 2010. Soil Water Chemistry during Conversion of Marginal Land to Biomass Crop Production in the Lower Mississippi Alluvial Valley. Soil and Water Conservation Society, Annual Meeting. St. Louis, Mo. 6/18/10-6/23/10

  Formby, K, Liechty, H.O., and Blazier, M. 2010. Monitoring Soil Water Chemistry During Establishment of Bioenergy Cropping Systems with Mixed Ion Resins: Limitations and Potential Improvements. 2010 ASA-CSSA-SSSA Annual Meeting, Long Beach, Ca. 10/31/10-11/3/10.

  Liechty, H.O. 2010. Bioenergy Crop Production and Water Quality in the Lower Mississippi Alluvial Valley. Arkansas Watershed Advisory Group Watershed Conference. Mt. Home, AR. 11/18/10-11/20/10.

  Blazier, M. and Liechty, H.O. 2011. Growing Energy Crops: An Agroforestry Approach. 2nd Annual Agroforestry Symposium. Columbia, Mo. 1/12/11.

  Blazier, M. 2010. Emerging Markets for Biofuels and Bioproducts. Landowner workshop, Dean Lee Research Station, Alexandria, La. 7/29/10

  Blazier, M. 2010. Emerging Markets for Biofuels and Bioproducts. Landowner workshop, Extension Office, Crowley, La. 9/29/10.

  Blazier, M. 2010. Emerging Markets for Biofuels and Bioproducts. Landowner workshop, Cleveland, Ms. 7/27/10

  Blazier, M. 2010. Food (and Forests) vs. Biofuel: Biofuel Management Impacts on Agriculture and Forestry. Tulane University Law School Summit on Environmental Law and Policy. 4/1/11.

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