Final report for GS22-273
Project Information
Biofuel is a renewable, plant-based substance grown and processed to generate fuel. Two primary categories of biofuels include first-generation and second-generation biomass. My research will focus on low-input, commercially available, perennial Texas bunchgrass species to find if they provide the necessary components to efficiently generate second-generation lignocellulosic bioenergy. With the highly invasive and input-dependent Bermudagrass as the predominant warm-season grass for hay crop, there exists a need for an equally productive and nutritious native bunchgrass with added potential as biofuel feedstock. The project hypothesizes that low-input, native Texas perennial bunchgrass species provide bioenergy feedstock and sufficient nutrition for ruminant animals. My study will look at two objectives: 1. determine the plant nutrient value at peak nutrition; and 2. evaluate end-of-season plant bioenergy potential. This research is novel and exciting as lignocellulose biomass-derived biofuels and biochemicals are emerging as a possible solution to increasing demand for sustainably farmed clean energy sources and encourage the use of sustainable grazing systems.
The objective of this study is to quantify and compare native and introduced bunchgrass species and their accessions in current Texas Native Seeds evaluation plots across five ecoregions (NW, NC, C, NE and SC Texas) for IVD, P, N, C, ADF, NDF, ash, and lignin contents, dry matter yields, height, base circumference, and canopy width. In addition, the project will compare summer plus autumn forage harvest versus single-autumn bioenergy harvest.
Cooperators
Research
1. Experimental design:
A three-factorial (location, species, and harvest system) experiment will be conducted across five plant material center locations in Texas: Stephenville, Nacogdoches, Lubbock, Knox City, and Kingsville. Plant species collections currently grown for accession comparison by Texas Native Seeds (Texas A&M University, Kingsville) vary by location and will be harvested twice per year over 2 years. The first harvest will occur in late spring when plants reach boot stage for forage peak nutrition and productivity. A second harvest will occur in autumn once plants reach peak bioenergy feedstock mass. Regrowth from forage plants harvested in the spring will be collected during autumn harvest. Field evaluation plots will be arranged in a randomized complete block design (RCBD) where two plants per replication are collected. I have already collected samples in the 2021 growing season and plans on collecting samples again from the same plots in 2022. Funding requested for this project will cover costs for lab assays from both years.
2. Collection location information:
Texas A&M AgriLife Research Center field evaluation plots in Stephenville are located at 32°15'09.4"N 98°11'35.2"W with fine loamy soil (USDA OSD, 2011), mean annual precipitation of 802 mm, annual high temperature of 24.3oC, and mean annual low temperature of 10.8oC (US Climate Data, 2022). East Texas Plant Materials Center in Nacogdoches is located at 31°31'44.0"N 94°46'08.3"W with fine sandy loam soil (USDA OSD, 2011), mean annual precipitation of 1,251 mm, annual high temperature of 24.9oC, and annual low temperature of 12.3oC (US Climate Data, 2022). Texas A&M AgriLife Research field plots in Lubbock are located at 33°36'05.1"N 101°54'28.3"W with silty clay loam soil (USDA OSD, 2011), mean annual precipitation of 487 mm, annual high temperature of 23.5oC, annual low temperature of 8.3oC (US Climate Data, 2022). Knox City Plant Materials Center is located at 33°26'44.1"N 99°51'27.6"W with black waxy and sandy loam soil (Anderson and Leffler, 2016), mean annual precipitation of 633 mm, annual high temperature of 24.6oC, and annual low temperature of 10.7oC. (US Climate Data, 2022). Kingsville Plant Materials Center is located at 27°31'55.4"N 97°53'15.4"W with loamy fine sand and sandy soil (USDA OSD, 2011), mean annual precipitation of 736 mm, annual high temperature of 28.4oC, and annual low temperature of 15.6oC (US Climate Data, 2022).
3. Plant species:
Native species’ Texas accessions currently being studied by Native Texas Seeds include: little bluestem (Schizachyrium scoparium), big bluestem (Andropogon geradi), side-oats grama (Bouteloua curtipendula), Indiangrass (Sorghumstrum nutans), eastern gama grass (Tripsacum dactyloides), switchgrass (Panicum virgatum), silver bluestem (Bothriochloa laguroides), and seep muhly (Muhlenbergia reverchonii). However, hooded windmill (Chloris cucullate) and Arizona cottontop (Trichachne californica) are collected from Lubbock rather than switchgrass. I will look at the best accessions for each species at each location, as defined by visual evaluation by Native Texas Seeds.
4. Harvests:
Prior to harvest, each plant will be measured for canopy width, height, and base circumference. Post-harvest, each plant will be weighed for wet weight and placed in a dryer. Dry weights will be recorded, thus providing dry matter yield percentage for yield per plant and yield per area. All plants will be ground using a Wiley Mill. They will be combined into spring and fall forage of the same accession, individual plants, and location as well as a single-harvest autumn biomass harvest of the same accession and location but different individual plants.
5. Nutrition:
Forage analyses will test for 1. in vitro digestibility via ANKOM Technology© Daisy Incubator with bovine rumen fluid collected from steers fed Cynodon dactylon hay with 12% crude protein; 2. nitrogen, carbon via Leco CN828 C: N analyzer; and 3. Lignin, ADF, NDF analyses are measured using via ANKOM Technology© Fiber Analyzer 200.
6. Biomass
Biomass quality will be evaluated by tested for 1. ASH content using a kiln 2. nitrogen, carbon via Leco CN828 C: N analyzer; and 3. Lignin, ADF, NDF analyses via ANKOM Technology© Fiber Analyzer 200.
7. Statistics
Data will be examined using analysis of variance (ANOVA) (Connelly, 2021) to compare species within locations as forage or bioenergy feedstock as measured by our dependent variables. Duncan’s Multiple Range Test (Lawrence, 1984) will compare multiple data sets across locations and species. Lastly, a regression model (Cline et al., 1977) will comparison of ASH content to rainfall (Han et al., 2011) in biomass analyses and temperature to yields. P values ≤ 0.10 wil be considered significant but values > 0.10 will be reported in the text so readers can decide for themselves what is significant.
Biofuel is a renewable, plant-based substance grown and processed to generate fuel. Forage is herbage used as feed by herbivores. My research focused on low-input, commercially available, perennial Texas bunchgrass species to find if they provided the necessary components to efficiently generate second-generation lignocellulosic bioenergy with flexibility to serve as a forage source, should markets favor one over the other. Highly invasive and input-dependent invasive forage species dominant warm-season grass hay crops, so a need exists for an equally productive and nutritious native bunchgrass with added potential as biofuel feedstock. I hypothesized that low-input, native Texas perennial bunchgrass species provide higher-yielding flexible-use bioenergy feedstock and forage for ruminants. I evaluated bioenergy potential of native grass accessions across two harvest regimens: 1. Forage harvested during the summer for ideal yield/nutritive value balance and 2. Biomass harvested at peak yield in late autumn. Established plants were sampled at five Texas locations (Kingsville, Knox City, Lubbock, Nacogdoches, and Stephenville) over 2 years. Based on comparing ratios of forage to biomass yields, the best flexible use species for both biomass and forage yields by location were 2-flower trichloras (ration = 0.852), big bluestem (ratio = 0.942), Indiangrass (ratio = 0.783), Arizona cottontop (ratio = 0.6), Indiangrass (ratio = 0.626), little bluestem (ratio = 0.646), and eastern gamagrass (ratio = 0.943).
Educational & Outreach Activities
Participation Summary:
A summary for online publication is being prepared based on this data.
Project Outcomes
Based on comparing ratios of forage to biomass yields, the best flexible use species for both biomass and forage yields by location were 2-flower trichloras (ration = 0.852), big bluestem (ratio = 0.942), Indiangrass (ratio = 0.783), Arizona cottontop (ratio = 0.6), Indiangrass (ratio = 0.626), little bluestem (ratio = 0.646), and eastern gamagrass (ratio = 0.943).
We learned that some native bunchgrasses are better for either forage or bioenergy feedstock but not both. Those that were equally viable for forage and bioenergy (closer to 1:1 yield ratios) tended to be the less productive. I also learned that collecting consistent data on practitioners' fields is challenging because land managers often manage in such a way that consistent data collection is not the priority.
We now have a species shortlist that we can continue to test on producers' fields. The search continues for high-yielding native bunchgrasses that are equally productive and have the appropriate nutrient contents for both forage (livestock feed) as well as bioenergy feedstock. I recommend scale-up and multiple-year trials in the future on producer land.