Beef production is at a crossroads in terms of environmental and economic sustainability.
Recently, grass-fed beef has gained popularity with consumers who are concerned about the
environmental impact of beef production and animal welfare. However, feedlot-finished beef
has been shown to have lower rates of greenhouse gas emissions than pasture-finished beef.
Here, we propose using tannin- and saponin-containing legume forages to lower greenhouse gas (GHG)
emissions and improve nitrogen (N) retention in pasture-finished beef systems. These forages
are known for reducing methane production in cows, reducing leachable N-inputs, reducing the
need for further N-additions, improving animal rate of gain, and preserving natural grassland
ecosystem services. However, it is still unclear how tannins and saponins function in the soil. Previous work
has shown that tannins reduce mineralization rates, although it is unclear whether this is a
function of tannin structure or concentration. Saponins are another secondary plant compound which have been
observed to have a similar function to tannins in the soil. To discriminate the effect of tannin or saponin source and
concentration on soil N-cycling, we propose an in vitro incubation study using varied doses of
condensed tannins from Lotus corniculatus (birdsfoot trefoil) and Onobrychis viciifolia
(sainfoin), and saponins from Medicago sativa (alfalfa) as opposed to commonly studied commercially-available
varieties, to monitor rates of N-mineralization, volatilization, and GHG production in pasture soil. Incorporating the
influence of N-cycling on soil GHG emissions will require a whole-farm environmental
sustainability assessment. Holos is a comprehensive and user friendly GHG accounting software
which uses a whole-farm approach to assess beef production environmental and economic
sustainability. Holos is currently designed for use in Canada, restricting its adoption in the U.S.
We propose to extend Holos’ geographic range and characteristics to include Utah for easier
adaptation throughout the Intermountain West. By training local producers and extension staff to
use Holos, we will facilitate its use while giving producers the ability to understand how
management changes affect environmental and economic sustainability.
1. Extract tannins from fecal samples produced by cows that have grazed on birdsfoot trefoil (BFT) and sainfoin (SFN)
tannin-containing legumes to determine a baseline tannin concentration that we would expect to see in the field in April 2018. We will also extract tannins from the leaves of BFT and SFN plants, and saponins from the leaves of ALF plants in April 2018. The tannins and saponins extracted from these leaves will be added to the soils during the incubation study and used as assay standards.
2. Perform a 84-day soil incubation study with varying concentrations of tannins extracted
from BFT and SFN leaves, and a single concentration of saponins extracted from ALF leaves (May-June 2018).
3. Determine concentrations of NH4+, NO3-, and NH3 at the start and end of the incubation,
and throughout the study on the same days as headspace sampling (May-June 2018).
These data will be used to calculate rates of N mineralization.
4. Assay the secondary plant compounds in soil samples at the start and end of the incubation study (May-June
2018) to monitor their availability in soils. Soils will be assayed for autoclaved citrate extractable protein (ACE protein) prior to KCl extraction on each sampling date to determine the
amount of protein substrate available to be bound by tannins or saponins (May-June 2018). Soil
secondary plant compound extractions and ACE protein assay trials will be performed prior to the incubation study
to determine the amounts of each substrate needed for successful assay.
5. Determine concentrations of CO2 and N2O gases using gas chromatography throughout
the incubation to determine production rates of each gas as well as cumulative production
(May-June 2018). Headspace samples will be collected on days 0, 2, 7, 14, 28, 42, 56, 70, and 84.
6. Create Holos farm scenarios for feedlot-finished, and various pasture-finished (MBG,
BFT, SFN, ALF) beef production systems for Utah using climate and soil data from Utah sites
where pasture-based beef production is or could be carried out, and quantify GHG
emissions for each scenario in units of CO2 equivalents (CO2-eq) (April-June 2018).
7. Create print and electronic resources explaining the effect of tannin-containing legume
forages on livestock health and soil nutrient cycling in Utah (March 2019).
8. Host two half-day training sessions for regional producers and outreach personnel in
partnership with USU Extension to demonstrate the use of Holos software (April 2019).
9. Create an online video tutorial with partner researchers at Agriculture and Agri-Food
Canada where Holos was developed to demonstrate how to use Holos software and adjust
it for Utah soil and climate conditions (January 2019).
10. Evaluate how producers’ skills have changed with regard to Holos software abilities as
well as their understanding of how management changes influence farm sustainability
before and after the Holos training sessions (April 2019).
In Vitro Incubation Experiment:
We conducted an 84-day in vitro soil incubation experiment. This experiment used various sources and doses of condensed tannins to distinguish between the effect of tannin source and concentration on N cycling dynamics. A saponin treatment with one source and concentration was added to the experiment so that the affect of tannins could be compared against the affect of other secondary plant compounds found in legume forages.
Each treatment was added to 5 g oven dry equivalent of uniform 0-15 cm soil sampled from under grass located adjacent to the pastures at the Utah State Intermountain Irrigated Pasture Project (USU IIPP) in Lewiston, Utah. Soil samples were collected on October 29, 2018 using a step-in soil corer. Soils were homogenized, sieved to 2 mm, and stored at 5 degrees celsius until use.
The experiment consisted of 6 treatments:
- Soil control (Control)
- Birdsfoot trefoil tannins @ 3 mg tannins/g dry soil (BFT Low)
- Birdsfoot trefoil tannins @ 15 mg tannins/g dry soil (BFT High)
- Sainfoin tannins @ 3 mg tannins/g dry soil (SFN Low)
- Sainfoin tannins @ 15 mg tannins/g dry soil (SFN High)
- Alfalfa saponins @ 3 mg saponins/g dry soil (SAP Low)
Treatments were added to 5 g of the uniform soil by dissolving the dry tannins or saponins in double distilled de-ionized water. All treatments were created to deliver the correct concentration of secondary plant compounds and bring the samples to 22% moisture (approximate field capacity). Each sample was placed in a 40 mL borosilicate glass incubation vial and sealed with caps fitted with septa. Each treatment contained 39 samples: 3 samples for ammonium (NH4+) and nitrate (NO3-) extractions on days 0, 2, 7, 14, 28, 42, 56, and 70; 3 samples for NH4+, NO3- on day 84 and headspace (carbon dioxide (CO2) and nitrous oxide (N2O)) sampling throughout the experiment; 6 samples for autoclaved citrate extractable protein (ACE protein) – 3 samples for day 0, and 3 samples for day 84; and 6 samples for secondary plant compound analysis – 3 samples for day 0, and 3 replicates for day 84. In addition to the 39 samples of each treatment, 3 empty jars were used as blanks and were preserved throughout the experiment (237 samples total).
Tannins were extracted from plant leaves grown at the USU IIPP according to Hagerman (2011) and purified according to Grabber et al. (2013). Tannins were also assayed from freeze-dried fecal samples collected in June 2017 from cows grazing exclusively on each forage. This was done to provide a reference value for tannin concentrations being deposited in the field. Saponins were extracted and purified according to Lee et al. (2001).
On each sampling day (0, 2, 7, 14, 28, 42, 56, 70, 84), NH4+ and NO3- concentrations were determined by performing a 2M KCl extraction on the soil. Extracts were analyzed using a Lachat Quikchem 8500 Flow Injection analyzer (Lachat Instruments, Loveland, CO, U.S.).
On each sampling day, 7 mL headspace samples were taken using a syringe and analyzed for concentrations of CO2 and N2O. Concentrations of CO2 were analyzed on a HP 6890 Series Gas Chromatograph System (Hewlett-Packard, Palo Alto, CA, U.S.). Concentrations of N2O were analyzed on an Agilent Technologies 6850 Series II Network GC System (Agilent Technologies, Santa Clara, CA, U.S.). Jars were flushed to ambient atmospheric conditions after each sampling event. Headspace samples were collected from the same 3 experimental replicates of each treatment throughout the experiment.
Samples were analyzed for ACE protein on days 0 and 84 according to Hurisso et al. (2018). Protein analysis was conducted to assess the amount of soil protein available in the soil at the start and end of the incubation. This acted as a proxy for the amount of protein which was bound by secondary plant compounds throughout the experiment.
Secondary plant compounds were analyzed according to the hot water method described in Halvorson & Gonzalez (2008). Samples were subjected to one cold water, and three subsequent hot water extractions. Cold and hot water extracts were analyzed for concentrations of dissolved organic carbon and total dissolved nitrogen. Extracts were analyzed on a Shimadzu TOC-L Analyzer (Shimadzu Corporation, Kyoto Japan).
Concentrations of soil NH4+ and NO3- were used to calculate rates of N mineralization. Concentrations of N2O were used to calculate rates of denitrification, and concentrations of CO2 were used to monitor microbial activity.
Data was analyzed using a mixed linear model and a randomized complete block design for analysis of variance using the MIXED procedure in SAS Studio University Edition (version 9.4, SAS Institute Inc., Cary, NC, U.S.). Parameters were analyzed for the main effects of treatment, day, and their interaction at p<0.05. Parameters were transformed as necessary to attain normality. Outliers were removed by assessing residuals.
Grabber, J.H., W.E. Zeller, and I. Mueller-Harvey. 2013. Acetone enhances the direct analysis of procyanidin- and prodelphinidin- based condensed tannins in Lotus species by the butanol-HCl-assay. J. Agric. Food Chem. 61: 2669–2678.
Hagerman, A.E. 2002. Tannin Purification.
Halvorson, J.J., and J.M. Gonzalez. 2008. Tannic acid reduces recovery of water-soluble carbon and nitrogen from soil and affects the composition of Bradford-reactive soil protein. Soil Biol. Biochem. 40(1): 186–197.
Hurisso, T. T., Moebius-Clune, D. J., Culman, S. W., Moebius-Clune, B. N., Thies, J. E., & van Es, H. M. 2018. Soil Protein as a Rapid Soil Health Indicator of Potentially Available Organic Nitrogen. Agricultural & Environmental Letters, 3(1).
Lee, Stephen T., Bryan L. Stegelmeier, Dale R. Gardner, and Kenneth P. Vogel. 2001. The isolation and identification of steroidal sapogenins in switchgrass. Journal of Natural Toxins. 4: 273-281.
Stark, J.M., and S.C. Hart. 1996. Diffusion Salt Solutions, Kjeldahl Digests, and Persulfate Digests for Nitrogen-15 Analysis. Soil Sci. Soc. Am. 60: 1846–1855.
Holos Greenhous Gas Emission Modeling:
We created Holos software scenarios for various pasture-finished beef production systems for the Intermountain West. Holos is a whole-farm life cycle greenhouse gas modeling software developed by Agriculture and Agri-Food Canada for animal agriculture operations. The four pasture-finished scenarios represented beef finished on an alfalfa, birdsfoot trefoil, sainfoin, or meadow bromegrass diet. The scenarios were adjusted to reflect soil, climate, and yield conditions in Utah based on data taken from the USU IIPP, USU Caine Dairy Farm, and the Utah Climate Center. Greenhouse gas emissions were quantified in units of CO2 equivalents. Using a modeling approach allowed us to simulate how changes in soil N cycling dynamics as a result of the presence or absence of tannin- and saponin-containing forage legumes affected total greenhouse gas emissions at the farm scale.
Holos Software: http://www.agr.gc.ca/eng/science-and-innovation/agricultural-research-results/holos-software-program/?id=1349181297838
In Vitro Incubation Experiment:
Results and Discussion
Significant differences (p<0.0001) in soluble N among the CT and saponin treatments suggested that CTs were capable of increasing N retention (Figure 1). The control yielded significantly more N than any of the BFT or SFN treatments and yielded equal amounts of N as the 3 mg/g SAP treatment, which was also equal to the 15 mg/g SFN treatment. Both the 3 mg/g SAP and 15 mg/g SFN treatments were significantly higher than the remaining BFT and 3 mg/g SFN treatments. This suggests that all CT treatments are complexing with organic N and increasing N retained in the soil. Reductions in soluble N are consistent with past studies. Like Halvorson et al. (2016), reductions in soluble N by the CTs were dose dependent when the 15 mg/g SFN treatment was excluded, consistent with the idea that CTs increase N retention via complexation with organic and mineral N.
Although there were significant differences in yields of soluble total (p<0.0001) and organic (p<0.0001) C among treatments, the secondary compounds appeared to have a lesser effect on C cycling than N cycling (Figure 1). The 15 mg/g SFN and 3 mg/g SAP treatments yielded significantly more soluble TC than the rest of the treatments, followed by the 15 mg/g BFT treatment which yielded significantly more soluble TC than the remaining control, 3 mg/g BFT and SFN treatments. The control yielded significantly more soluble TC than the 3 mg/g SFN treatment and the 3 mg/g BFT treatment did not differ from the control or 3 mg/g SFN treatment. Similar results were seen for total soluble organic C yields, as the 15 mg/g SFN and 3 mg/g SAP treatments, followed by the 15 mg/g BFT treatment, yielded significantly greater soluble organic C than the control or 3 mg/g BFT or SFN treatments. The 3 mg/g BFT and SFN treatments yielded significantly less soluble organic C than the control. This suggests that low concentrations of CTs may be binding soil organic matter since they did not yield significantly more soluble total C or organic C than the control, despite adding C to the soil samples. Reductions in soluble C and organic C provided evidence of CT sorption to SOM at low concentrations, but not in the dose dependent manner discussed in prior literature (Northup et al., 1995; Kraus et al., 2003; Adamczyk et al., 2012; Halvorson et al., 2016)
Nitrogen mineralization patterns provided some evidence for increased N retention, as well as phenolic degradation and subsequent immobilization. There were significant treatment x day interactions for NH4+ (p<0.0001) and NO3– concentrations (p<0.0001) (Figure 2). At the start of the incubation, the 15 mg/g SFN treatment had significantly higher NH4+ concentrations than the control, and the control treatment had significantly lower NH4+ concentrations than the remaining treatments. When NO3– concentrations were compared among treatments by day, there was evidence of immobilization and subsequent mineralization in all treatments.
By the end of the incubation, the 3 mg/g SAP and the 15 mg/g BFT treatments had significantly lower NO3– concentrations than the 3 mg/g BFT and SFN treatments and the control. The 15 mg/g SFN treatment continued to be significantly higher than the 15 mg/g BFT and 3 mg/g SAP treatments. However, none of the treatments had NO3– concentrations that exceeded the control. This confirms that the treatments did not add significant amounts of N to the samples and suggest that low concentrations of saponins and high concentrations of CTs may decrease N mineralization. Although the ammonium data did not directly support the idea of phenolic-driven N complexation, the nitrate data did. The lower nitrate concentrations in the 15 mg/g BFT and 3 mg/g SAP treatments did confirm that phenolics, including saponins, can inhibit N mineralization over a prolonged period (Crush, 1993; Northup et al., 1995; Crush and Keogh, 1998; Schimel et al., 1998; Kraus et al., 2003; Nierop et al., 2006a; b; Smolander et al., 2012).
The addition of the phenolic treatments generally did not increase total N2O emissions over the course of the incubation. There was a significant treatment x day interaction for N2O production rate (p=0.0064) and cumulative N2O production (p<0.0001) (Figure 3). On day 84, the 3 mg/g BFT treatment had significantly higher N2O production rates than the 3 mg/g SFN treatment, and the 15 mg/g SFN treatment had significantly higher N2O production rates than the 3 mg/g SFN treatment. The 15 mg/g SFN treatment had significantly higher cumulative N2O production than the control treatment on days 2 , 7 , and 14 , and the 3 mg/g SAP and SFN Low treatments on days 2 and 7. On day 2, the 15 mg/g BFT treatment had significantly higher cumulative N2O production than the control or 3 mg/g SAP treatments. There was a significant treatment effect for total N2O production (p<0.0001) (Figure 3). The 15 mg/g SFN treatment had significantly higher total N2O production than all other treatments. This suggested that none of the secondary compound additions except for the high dose SFN treatment stimulated significant N2O production over a prolonged period of time. Total N2O production was significantly higher in the 15 mg/g SFN treatment, but was likely due to the high NO3– concentrations found in that treatment. Despite this, the 15 mg/g BFT and 3 mg/g SAP treatments was able to reduce mineral N pools without stimulating N2O production at low doses, suggesting a complexation reaction with soil N.
The secondary compound treatments appeared to provide a C source and increased C mineralization. There was no treatment effect for CO2 production rate, but there were significant treatment effects for cumulative (p<0.0001) and total CO2 production (p<0.0001) (Figure 4). The 15 mg/g SFN and BFT treatments had significantly higher cumulative CO2 production than all other treatments, indicating a stimulatory effect from high doses of CTs. The 3 mg/g SAP and SFN treatments had significantly greater cumulative production than the control indicating a lesser stimulatory effect. The 3 mg/g BFT treatment’s cumulative production was intermediate to the control, 3 mg/g SAP, and 3 mg/g SFN treatments. By the end of the incubation the only significant differences in total CO2 production were observed for the 15 mg/g SFN and BFT treatments which had significantly higher total CO2 production than the rest of the treatments. This suggests a stimulatory effect of CTs on C mineralization at high doses. The effect of tannins on CO2 production in the literature has been mixed. The dose-dependent effect on C mineralization observed in our study would suggest that C from the CT treatments was used as a labile C source, as several past studies have indicated (Schimel et al., 1998; Nierop et al., 2006a; b).
There was a significant treatment x day interaction (p<0.0001) for ACEP (Figure 1). On day 0, the 15 mg/g SFN and BFT treatments yielded significantly more ACEP than all treatments. By day 84, the 15 mg/g BFT treatment only yielded more ACEP than the 3 mg/g SAP and control treatments. This indicates that protein generally decreased through time, but decreased significantly more for the 15 mg/g BFT and SFN treatments. Past studies have used now outdated measures of soil protein such as Bradford reactive soil protein, and our data will need to be compared against future studies. The apparent dose-dependent increase in ACEP would suggest that the assay is either extracting proteins contained in the treatments, or that high doses of CTs make soil protein more available since reduction in soluble C was not dose dependent.
Soil N cycling results for ammonium, nitrate, and N2O production were unexpectedly high for the 15 mg/g SFN treatment and caused concerns of possible N contamination in that treatment. Upon further analysis, the 15 mg/g SFN treatment was the only treatment with detectable amounts of total N. Since the basic catechin and epicatechin building blocks of condensed tannins do not contain N, it is suspicious that the SFN, but not the BFT treatments, would add such a considerable amount of N. Statistical analysis was run with and without the 15 mg/g SFN treatment included. The removal of the 15 mg/g SFN treatment did not generally alter the results of the experiment or our conclusions. Despite the results of the 15 mg/g SFN treatment, low doses of saponins and high doses of BFT-derived condensed tannins did appear to increase soil N retention in a pasture soil.
Adamczyk, B., J.P. Salminen, A. Smolander, and V. Kitunen. 2012. Precipitation of proteins by tannins: Effects of concentration, protein/tannin ratio and pH. Int. J. Food Sci. Technol. 47(4): 875–878. doi: 10.1111/j.1365-2621.2011.02911.x.
Crush, J.R. 1993. EFFECT OF TANNIN IN ANIMAL DIET ON NITRIFICATION RATE OF PASTURE SOIL UNDER DUNG PATCHES. AgResearch Session 8(ID No. 576): 1991–1992.
Crush, J.R., and R.G. Keogh. 1998. A comparison of the effects of Lotus and white clover on some nutrient cycling factors. Proc. New Zeal. Grassl. Assoc. 60: 83–87. https://www.grassland.org.nz/publications/nzgrassland_publication_220.pdf (accessed 25 July 2017).
Halvorson, J.J., M.A. Schmidt, A.E. Hagerman, J.M. Gonzalez, and M.A. Liebig. 2016. Reduction of soluble nitrogen and mobilization of plant nutrients in soils from U . S northern Great Plains agroecosystems by phenolic compounds. Soil Biol. Biochem. 94: 211–221. doi: 10.1016/j.soilbio.2015.11.022.
Kraus, T.E.C., R.A. Dahlgren, and R.J. Zasoski. 2003. Tannins in nutrient dynamics of forest ecosystems-a review. Plant Soil 256: 41–66. doi: Doi 10.1023/A:1026206511084.
Nierop, K.G.J., C.M. Preston, and J.M. Verstraten. 2006a. Linking the B ring hydroxylation pattern of condensed tannins to C, N and P mineralization. A case study using four tannins. Soil Biol. Biochem. 38: 2794–2802. doi: 10.1016/j.soilbio.2006.04.049.
Nierop, K.G.J., J.M. Verstraten, A. Tietema, J.W. Westerveld, and P.E. Wartenbergh. 2006b. Short- and long-term tannin induced carbon, nitrogen and phosphorus dynamics in Corsican pine litter. Biogeochemistry 79(3): 275–296. doi: 10.1007/s10533-005-5274-0.
Northup, R.R., Z. Yu, R.A. Dahlgren, and K.A. Vogt. 1995. Polyphenol control of nitrogen release from pine litter. Nature 377: 227–229.
Schmidt, E.L., and L.W. Belser. 1994. Autotrophic nitrifying bacteria. p. 159–177. In Methods of Soil Analysis, Part 2. Microbiological and Biochemical Properties – SSSA Book Series, no. 5. Soil Science Society of America, Madison, WI.
Smolander, A., S. Kanerva, B. Adamczyk, and V. Kitunen. 2012. Nitrogen transformations in boreal forest soils — does composition of plant secondary compounds give any explanations ? Plant Soil 350: 1–26. doi: 10.1007/s11104-011-0895-7.
Holos Greenhouse Gas Emission Modeling:
Results and Discussion
Holos software scenarios for all beef-finishing scenarios are currently in the final stages of preparation. Preliminary results suggest that legumes may decrease total greenhouse gas emissions when expressed per kg of live weight gain. In a direct comparison of birdsfoot trefoil, meadow bromegrass, and cicer milkvetch finishing systems, the grass-finished system appeared to have the highest total greenhouse gas emissions due to N fertilizer use and low feed quality. The use of both tannin- and non-tannin-containing legumes lowered enteric methane production, N fertilizer use, and overall greenhouse gas emissions compared to a grass system. In a separate comparison of alfalfa, birdsfoot trefoil, and sainfoin finishing systems, all three systems minimized external N inputs due to the use of legumes. Although further adjustments are being made to these scenarios, forage yield and amount of residue left on the field appear to be important determinants of total greenhouse gas production in legume finishing systems. At this time, the Holos greenhouse gas models may not be sensitive enough to distinguish the effects of tannin- vs. non-tannin-containing legume finishing systems on whole-farm greenhouse gas emissions.
Educational & Outreach Activities
1) Preliminary data from the in vitro incubation experiment was presented as a poster at the Soil Science Society of America 2018-2019 International Soils Conference in San Diego, CA on January 7th, 2019 by graduate student Kathryn Slebodnik.
2) A Holos informational presentation was presented at the 2019 Urban and Small Farms Conference in West Valley City, UT on February 21st, 2019. Co-presenters included graduate student Kathryn Slebodnik and collaborator Dr. Roland Kroebel from Agriculture and Agri-Food Canada. The presentation was attended by ~30 participants which included local producers as well as Utah State research and extension faculty.
3) A Holos training workshop was presented by Dr. Roland Kroebel, Dr. Sarah Pogue, and Aaron McPherson from Agriculture and Agri-Food Canada with assistance from graduate students Kathryn Slebodnik and Anthony Whaley immediately after the Urban and Small Farms Conference at the Utah Cultural Celebration Center in West Valley City, UT on February 21, 2019. Unfortunately, there were no attendees.
4) A second Holos training workshop, hosted by the same presenters as above, was held at Utah State University on February 22, 2019. The workshop was attended by 7 participants, including 2 research faculty, 4 graduate students, and 1 producer from a local dairy operation. The workshop trained attendees to use Holos software by walking them through a hands-on demonstration where they modeled a typical beef production operation. Participants practiced modeling alternative management strategies and analyzing their impact on the GHG intensity of the beef produced. All participants completed a pre- and post-workshop survey. This survey assessed how participants’ thoughts and attitudes towards Holos software and on-farm environmental and economic planning had changed over the course of the presentations and workshops. Attendees were provided with an instructional handout to follow and take home for future reference.
4) Preliminary data from the in vitro incubation experiment was presented as a poster at the Intermountain Sustainability Summit at Weber State University in Ogden, UT on March 21, 2019 by graduate student Kathryn Slebodnik. Poster from event #1 was presented.
5) Preliminary data from the in vitro incubation experiment was presented during an oral presentation at the Utah State University Dept. Plants, Soils and Climate Seminar Series in Logan, UT in March 18, 2019 by graduate student Kathryn Slebodnik.
6) Preliminary data from the in vitro incubation experiment was presented as a poster at the Utah State University Department of Plants, Soils and Climate Department Showcase in Logan, UT on March 25, 2019 by graduate student Kathryn Slebodnik.
7) Preliminary data from the in vitro incubation experiment was presented as a poster at the Utah State University Student Research Symposium in Logan, UT on April 10-11, 2019 by graduate student Kathryn Slebodnik. Poster from event #6 was presented.
8) Final data from the in vitro incubation experiment was presented as a poster at the American Society of Agronomy Annual Meeting in San Antonio, TX on November 13, 2019 by principal investigator Dr. Jennifer Reeve.
9) Final data from the in vitro incubation experiment has been included in graduate student Kathryn Slebodnik’s masters thesis. Kathryn’s thesis was successfully defended on December 3, 2019 and is in the final stages of revision and review by the academic committee and Utah State University’s office of graduate studies. Data from the in vitro incubation experiment will be submitted to peer review journals such as Soil Biology and Biochemistry or Agriculture, Ecosystems & Environment in 2020.
This project will contribute to future economic, environmental, and social sustainability of beef production in the Intermountain West. By finishing beef on tannin- and saponin-containing legume forages, producers will likely be able to increase the productivity of pasture-finished beef by increasing forage quality and increasing the average daily gains of cattle. This will allow them to produce higher quantities of high-quality beef over the course of the growing season. The use of nitrogen (N)-fixing legumes will further increase the profitability of pasture-finished beef by reducing the amount of N fertilizer and additional feed required. The use of these tannin- and saponin-containing perennial legumes further increase profits by reducing annual seeding costs.
The adaptation of these tannin- and saponin-containing legumes will also increase environmental sustainability. Based on nitrogen cycling results, low doses of tannins and saponins may be able to inhibit N mineralization. This may decrease the amount of N leached in local surface runoff as well as N lost as greenhouse gases such as nitrous oxide. The results of this study demonstrate that low concentrations of tannins and saponins may inhibit soil N mineralization without increasing greenhouse gas production. This will improve local water quality and potentially reduce greenhouse gas emissions on a whole-farm, life cycle basis.
This project will produce social benefits for producers and the greater community. The outreach portion of this project will give producers the skills they need to use Holos software for their own operations. This will allow producers to evaluate and share the impact that management changes have on the environmental and economic sustainability of their farm. The adaptation of tannin- and saponin-containing legumes will increase the availability of more sustainably-finished beef products to the local community, as well as improve local environmental quality.
Based on the results of the pre- and post- workshop survey (7 participants), the session was rated “very effective” by 83% and “moderately effective” by 17% of respondents at demonstrating the capabilities of Holos software as an economic and environmental decision-making tool. All respondents reported a gain or increase in knowledge, awareness, and skills about sustainable agriculture topics, practices, strategies, and approaches. 67% of respondents anticipated using knowledge they gained from the workshop in new or existing educational programs. Respondents were also asked about the effort they anticipated putting into future economic decision making. Of those who responded, 79% reported that their effort would “increase a little” to “a lot” after the session, while 17% reported no anticipated change. When asked about the effort they anticipated putting into future environmental decision making, 80% reported that their effort would “increase a little” to “a lot” after the session, while 17% reported no anticipated change.
My attitude and awareness of sustainable agriculture has increased because of this project. The development and preparation of this WSARE project has allowed me to improve my field and laboratory skills, improve my ability to draw conclusions based on several data sets, facilitate new connections with researchers and outreach coordinators, and gain experience preparing outreach activities. This WSARE project experience has highlighted the importance of being able to perform specific, mechanism-driven scientific experiment, and transform the results into concise conclusions and management recommendations that will benefit scientists, producers, and the general public. The outreach portion of this project has reinforced the importance of sharing the results of scientific activities not only with other scientists, but with producers and land managers who can put these sustainable practices into action. Planning outreach workshops has supported my enthusiasm for sustainable agriculture-based extension activities which I hope to pursue in my future career. This project has also allowed me to attend conferences where I made connections with other scientists conducting sustainability research and learned about other novel sustainable agriculture research.