Home | 2007 Annual Report

The Evaluation of Selected Perennial Grasses for Biofuel Production in Central and Western North Dakota

Paul E. Nyren, Eric Eriksmoen, Gordon Bradbury, Mark Halverson, Ezra Aberle, Kristy Nichols, Mark Liebig, and Bob Patton

Summary

A study began in the spring of 2006 to evaluate the production, carbon sequestration, economics, and longevity of 10 perennial grasses in central and western North Dakota. These grass plots were harvested during the second week of September 2007. Results of this first year’s harvest indicate that the warm season grasses (switchgrass and big bluestem) require more precipitation to achieve adequate yields. On the drier sites at Hettinger, Williston, and Central Grasslands (Streeter), tall and intermediate wheatgrass yielded higher than did switchgrass and big bluestem. On the wetter sites at Carrington, and under irrigation at Williston, switchgrass outyielded the wheatgrass species.

The North Dakota Natural Resources Trust has joined with the North Dakota State University (NDSU) Central Grasslands Research Extension Center (CGREC) in Streeter, USDA-ARS Northern Great Plains Research Laboratory in Mandan, ND, North Dakota Game and Fish Department, North Dakota Commerce Department, and others to develop a dedicated bioenergy crop study to determine the appropriate grass species, harvest methods, and practices to maintain productive perennial biomass stands. The economics for production of a bioenergy crop will be evaluated, as well as the impact on soil organic matter and carbon storage.

At the turn of the century, with the exception of trains and water transportation, the transportation and agriculture industries of the U.S. were powered largely by herbaceous biomass. This biomass was converted to usable energy by draft animals, primarily horses and mules. Today’s increased use of agricultural commodities (corn, soybeans, and their byproducts) for energy production results in resources moving away from feed and food production. Dedicated grasses, such as switchgrass and other perennial grasses, require less energy to maintain once they are established. Since the areas in which they can be grown are much more diverse, a dedicated energy crop like perennial grasses offers a wider geographical impact than corn or soybeans and has a more positive impact on soil conservation and wildlife habitat. North Dakota has over seven million acres of highly erodible and saline cropland, with some counties in the western part of the state having as high as 90 percent of the cropland classified as highly erodible. Perennial energy crops would achieve more long-term sustainability on these lands by reducing erosion, adding organic matter, reducing greenhouse gases, and sequestering carbon. These crops also provide better economic stability for the producer and the community. Several publications have indicated that North Dakota could be a leading state in the production of biomass from herbaceous crops.

Objectives

1. Determine the biomass yield and select chemical composition of perennial herbaceous crops at several locations throughout central and western North Dakota.

2. Determine the optimum harvest dates for maximum biomass yield and maintenance of the stands.

3. Compare annual and biennial harvest for total biomass yield and maintenance of the stands.

4. Evaluate carbon sequestration and storage of the various perennial crops.

5. Evaluate the economic feasibility of the various perennial herbaceous energy crops with competing crops in the surrounding area.

Methods

In the spring of 2006, plots were seeded at five locations across central and western North Dakota. Dryland plots were located at the Hettinger Research Extension Center (REC), Williston REC, North Central REC at Minot, Carrington REC, and Central Grasslands REC at Streeter. In addition, a set of irrigated plots was seeded at the Williston REC.

Soils

In May 2006, prior to seeding, Dr. Kristy Nichols and Dr. Mark Liebig, research scientists from the USDA-ARS Northern Great Plains Field Laboratory in Mandan, ND, collected baseline soil samples. These samples were divided into seven depths (0-2, 2-4, 4-8, 8-12, 12-24, 24-36, and 36-48 inches). They were processed for gravimetric water content and soil bulk density prior to air drying for soil quality parameters or sub-sampling. Soil quality measurements included electrical conductivity, soil pH, total carbon and nitrogen, soil inorganic carbon, particulate organic matter, and extractable nitrate and phosphorus.

During 2007, laboratory analyses were completed for the baseline soil samples collected in May 2006. Results were summarized by location and shared with on-site collaborators. These data will be used to assess changes in soil condition as well as calculate soil carbon accrual/loss rates following subsequent samplings in 2011 and 2016. Aggregation and glomalin concentration were also determined and the results tabulated.

Seeding and Harvest

The plots were seeded the week of May 15, 2006, starting in Hettinger and ending in Carrington. Table 1 shows the species that were seeded at each location, whether they will be harvested annually or biennially, and the seeding rate. The plots were seeded with a plot drill designed and built at the USDA-ARS lab in Mandan by Mr. Louie Zachmeier (Figure 1). The drill was designed to seed small-seeded grasses and legumes and is equipped to seed 10 rows on 6-inch centers. Each plot measured 15 X 30 feet and required three passes with the drill.

While the summer of 2006 was dry in most of the locations, initial reports on the plots were encouraging. The plots were sprayed and mowed at least once at all locations except Hettinger, where they received only chemical applications.

In 2007, both the annual and biennial plots were harvested during the second week in September. A self-propelled plot harvester provided by the USDA-ARS in Mandan was used on all sites (Figure 2). A 4 foot-wide strip in the center of each plot was cut and weighed by the machine. A small subsample of the forage was then collected and the wet weight was recorded. The subsamples were then dried and reweighed to get the percent moisture. This value was then applied to the entire sample. The samples were subsequently ground in preparation for laboratory analysis. All weights in Tables 2 and 3 are oven-dry weights.

Results

Table 2 shows the results of the analysis of the yield data for the plots at each location. The yields followed by the same letter are not significantly different (p≤0.05 level). This means that if this test were repeated 100 times, we are confident that 95 times we would get the same results.

As you can see from table 2, the plots at Carrington yielded by far the best of the dryland sites. The irrigated plots at Williston also yielded very well (Table 3 and Figure 4). On the dryland plots at Hettinger, Williston, and Streeter, the plots of switchgrass and the switchgrass-big bluestem mix had very poor stands. This was probably due to the combination of the dry summer of 2006 and winter kill. A close examination was made of the switchgrass plots at Streeter, and switchgrass plants were present in September of 2006; however, very few of these plants were observed in the spring of 2007. The plots at North Central in Minot had a better yield, but they had a heavy weed in- festation at harvest. The plots at Carrington had by far the best stand, again due to the soils and precipitation during the summers of 2006 and 2007 (Figure 3).