Progress report for GW24-011
Project Information
Cheatgrass/downy brome (Bromus tectorum) and ventenata (Ventenata dubia) are a large concern for producers in rangelands across the West. These species can reduce perennial forage grasses, negatively impacting ecosystem services and the sustainability of cattle operations. Managing these species is difficult, and many producers are interested in new viable weed management tools. One potential is the micronutrient soil amendment Nutrafix, designed to improve soil health and perennial forage. A potential side effect is the reduction in several weedy species, including cheatgrass and ventenata. However, damage to mature perennial grasses has been reported. Our goals are to improve our understanding of this soil amendment through its impacts on seed germination and establishment of native and non-native species, and its impacts on forage quality and soil health. We will address these goals through four studies. In a controlled environment we will assess the impact of Nutrafix on 1) germination and 2) seedling emergence of three native and two non-native grasses; and 3) on biomass and forage quality of mature native grasses. Our field study 4) will assess forage and soil quality in previously established plots assessing the impact of Nutrafix on cheatgrass management. We will share the outcomes of this research with producers through extension publications, peer reviewed publications, and scientific presentations. The findings from these studies will allow producers to make more informed decisions when considering using Nutrafix to improve their soil health and their native perennial forage quality, both of which can help improve the sustainability of their land.
The research goals of this project are to improve our understanding of how the soil amendment Nutrafix impacts seed germination and establishment of native and non-native grasses, as well as how it impacts forage quality of mature forage grasses. To achieve our goals we have four objectives.
Objective 1:
Determine the impact of different rates of Nutrafix on seed germination and dormancy of three native species (bluebunch wheatgrass (Pseudoroegneria spicata), Idaho fescue (Festuca idahoensis), and western wheatgrass (Pascopyrum smithii)), and two non-native species (cheatgrass and ventenata) in non-soil media, in a growth chamber. (Fall 2024)
Objective 2:
Determine the impact of different rates of Nutrafix on seedling establishment of the same five native and non-native species in soil media, in a greenhouse. (Fall 2024)
Objective 3:
Determine the impact of the recommended rate of Nutrafix on mature native plant species biomass and forage quality in soil media, in a greenhouse. (Winter 2024/2025)
Objective 4:
Determine the impact of Nutrafix on a) forage quality of the native species and b) soil nutrient availability, four years post application in a field setting. (Summer 2024)
The educational goals of this project are to further educate Montana producers and managers about the specific impacts of Nutrafix on native and non-native species germination and emergence, as well as its impacts on the quality of native forage species and soil nutrient availability. To assess these goals we have one objective, with three sub-objectives.
Objective 5: Share our results about the impact of Nutrafix on native and non-native grass germination and establishment, as well as native forage and soil quality.
a) Supply condensed highlights of these results to producers and managers through extension fact sheets and online resources. (Winter-Fall 2025)
b) Present our results to producers and managers through local scientific meetings and field days. (Spring-Summer 2025)
c) Publish these results through peer-reviewed publications in research journals. (Fall 2025)
Cooperators
- - Producer
- - Producer
- - Producer
Research
Objective 2: We will assess emergence of the native and non-native species using three different rates of aqueous boron in a soil media. However, given the issues we have had with the effect of similar aqueous boron rates in different media and conditions, we are currently performing a small preliminary trial before setting up the main experiment. The aim is to test the same five species at three aqueous boron rates (likely 0, 2.1, and 11.3 ppm), replicated five times, in two trials (n=120). Seeds will be planted in 12.5 cm round pots (10 seeds/pot). Soil will be an unpasteurized 1:2 loam:sand mix from the Plant Growth Center at Montana State University (Primer 2023). The greenhouse will be maintained at 23/6°C with 14/10 light/dark hours. The recommended rate of NutraFix (boron) or water (control) will be applied to the soil surface after planting. Pots will be watered from below as needed to prevent excessive leaching. Aboveground biomass will be harvested 30 days after emergence, (estimated to take 10-14 days) and dried at 43°C for three days before dry weight is obtained. At the time of harvest plant tissue will be visually assessed for evidence of chlorosis or necrosis and rated on a scale from 1-5 (1: not damaged– 5: very damaged). The soil will be analyzed for boron, other micronutrients, nitrogen, phosphorus, and potassium (NPK), soil organic matter (SOM), pH, and conductivity after harvest.
Objective 3: We assessed the impact of the recommended aqueous rate of NutraFix (boron, 10 ppm) on mature individuals of the native species (bluebunch wheatgrass, Idaho fescue, and western wheatgrass) in a greenhouse. Four replications and two trials will be completed (n=48), currently one trial has been completed and the second was started in April. For trial 1, plants were grown from seeds in tall, round pots (18 cm across and 40 cm tall), one plant per pot, using same soil, and greenhouse conditions as in Objective 2. Only six of the eight western wheatgrass individuals emerged, so there were only three replicates per treatment for that species in the first trial. Our native species were grown in individual pots for 20 weeks. Aboveground biomass was removed at weeks 10 and 20 to encourage growth. At the time of the second harvest, the 50 ml of a 10 ppm boron solution (or water) was applied and plants were placed in a cold storage growth chamber (4 °C /dark) for six weeks to simulate a winter dormancy period. Plants were then returned to the normal greenhouse and were allowed to grow for eight weeks before harvesting. Plant height (cm) was measured weekly during this last section to assess changes in growth. The level of damage was also assessed visually prior to harvesting. Plants were rated on a scale of 1-5 (1: not damaged – 5: very damaged). Plants were then harvested, split into above and belowground biomass, and dried at 43°C for three days before dry weight is obtained. Three replicates of tissue samples (per species and treatment) were analyzed by Cumberland Valley Analytical Services (CVAS) for boron presence and crude protein content (n=18). Upon receival, CVAS determined there was not enough biomass in each sample for analysis, so two reps of the same treatment/species combination were combined where possible. This limitation of replication will limit our analysis of boron and crude protein content.
High levels of damage in treated plants lead to reevaluation of the treatment concentration. After considering the volume and area of soil in our pots, the volume of solution we applied, and talking with Dr. Jones, we determined that our application rate was higher than intended. The study will be rerun, with a true application rate of 10 ppm. Due to time constraints, subsequent trials will be shorter than the initial trial. Plants will be allowed to grow for 15 weeks before treatment application occurs, 4 weeks in cold storage, and 6 weeks after removal from cold storage. All other factors will remain the same.
Objective 4: We assessed the lasting impact of NutraFix on native perennial forage grasses four-years post application using two previously established field sites (WSARE SW 20-915). A full factorial randomized study was established over two years at three sites. Two trials were established in the fall of 2020 (Red Bluff Research Ranch (Collaborator, Davis; Norris, MT) and the Highland ranch (Collaborator, Fleming; Livingston, MT)) – and we used these trials. (Three additional trials were established in the fall of 2021 (Red Bluff Research Ranch, Highland ranch, and the Emigrant ranch (Emigrant, MT; collaborator Pierce)). All sites are semi-arid grasslands in southwestern Montana. Each trial tested five replicates of seven treatments. For this proposal we assessed the first two trials established in 2020, and the treatments important to this proposal are the non-treated control and the recommended rate of NutraFix (417 kg/ha). The low and high NutraFix plots were not assessed due to the high cost of forage analysis. Individual plots were 1.25 x 2.5 m. Aboveground biomass of western wheatgrass and bluebunch wheatgrass were harvested from five replicates in each of the control and recommended NutraFix treatments in July 2024 (n=12). However, at the time of sampling there was not abundant levels of western wheatgrass and bluebunch wheatgrass in all plots. A total of 13 western wheatgrass forage samples were collected (7 control, 6 NutraFix) and 3 bluebunch wheatgrass samples (2 control, 1 NutraFix). The aboveground plant tissue was assessed for boron presence and crude protein content by CVAS. Similarly to Objective 3, several samples did not have enough biomass for analysis and some replications were combined, limiting our analysis. Soil samples assessing boron, other micronutrients, NPK, SOM, pH, and conductivity were collected in the summer of 2024 (n=12) and analyzed by Agvise laboratories. To strengthen these results, we will collect more field samples this coming summer. This time from the plots established in 2021, again giving us data on plots four years post treatment.
Analysis
Objective 1: Dose response curve analyses were performed in R using the drc package to quantify the rate of boron that reduced germination (ED50 and ED90) and performed linear mixed effects models to test for any significant reductions in radical and cotyledon lengths of the different species (Ritz and Strebig 2016). Linearity and equal variance assumptions were not met for cotyledon and radical models, so the response was log transformed. All results are presented on the original scale.
Objective 2: Impact of boron on seedling emergence, final aboveground biomass/pot, tissue damage, and soil metrics will be assessed with generalized linear mixed effect model (binomial distribution) (emergence) and linear mixed effect models (other responses), all with random variables to account for trial design.
Objective 3: Impact of boron on above and belowground biomass, visible damage, boron presence in tissues, and forage quality were assessed with linear models. The belowground biomass model violated the linearity and equal variance assumptions, so the response was log transformed. All results are presented on the original scale. Data on boron quantity and forage quality were limited, so full statistical analyses were not possible, but t-tests were performed where possible, and the data are graphed.
Objective 4: There were not enough replications in our data to fully statistically assess the impact of NutraFix 4 years post application on boron presence in aboveground tissues and forage quality, but t-tests were performed where possible, data were graphed, and loose observations were drawn. The soil metrics were assessed with linear mixed effect models with random variables to account for trial design.
Objective 1: Dose response analysis showed that bluebunch wheatgrass was the least impacted by boron application, followed by cheatgrass, then ventenata and Idaho fescue which did not differ from each other (Figure 1). It took 0.26 ppm of boron to reduce the germination of bluebunch wheatgrass by 50% and 0.81 ppm to reduce germination by 90% (Figure 1). It took 0.11 ppm of boron to reduce the germination of cheatgrass by 50% and 0.43 ppm to reduce germination by 90% (Figure 1). Germination of ventenata and Idaho fescue were reduced by 50% at 0.08 ppm and by 90% at 0.20 ppm (Figure 1).
Increasing rates of boron impacted both radical (p<0.001) and cotyledon length (p<0.001), and some of those impacts varied by species (p = 0.025). Increasing the boron application by 0.1 ppm resulted in a 9% decrease in radical length for all species (p<0.001; Figure 2). The same increase reduced cotyledon length by 5% for Idaho fescue, bluebunch wheatgrass, and ventenata (p<0.001; Figure 3). Cheatgrass cotyledon length was more impacted and had a 10% reduction (p = 0.003; Figure 3).
Objective 2: Experiment has yet to be performed. Timing was delayed due to limitations in available greenhouse space but is schedule to start in early summer 2025.
Objective 3: Preliminary analysis was performed on the first trial. We aimed to evaluate boron and crude protein content from individual plants, to understand variability between species and treatments. Unfortunately, the amount of biomass collected from individual plants was insufficient to perform the analyses, so replicates were combined. This greatly limited our ability to make statistical conclusions, but in all species, boron levels appear to be thousands of ppm higher in the plants treated with boron (Figure 4). More samples were able to be assessed for crude protein content (% dry matter), but still statistical analysis was limited. The mean crude protein in control Idaho fescue individuals was 13.7% and decreased to 11.7% in treated individuals (p = 0.648; Figure 5). For western wheatgrass, crude protein was 8.1% in control plants and 17.0% in treated plants (Figure 5). For bluebunch wheatgrass, protein was 7.9% in control plant and 13.5% in treated plants (p = 0.021; Figure 5).
Preliminary analysis of aboveground biomass revealed that plants treated with boron were on average 1.4 g smaller than non-treated control plants (p = 0.005; Figure 6), and there was no difference among the three species (p = 0.324; Figure 6). Boron application also had an impact on belowground biomass, with treated plants having an average of 60% less biomass accumulation than non-treated controls (p = 0.042; Figure 7). Again, species did not differ in their responses (p = 0.244; Figure 7). Visual observations revealed that plants treated with boron often appeared more damaged, with leaves often displayed chlorosis or senescence (Figure 8).
Objective 4: A total of 13 western wheatgrass forage samples were collected (7 control, 6 NutraFix) and 3 bluebunch wheatgrass samples (2 control, 1 NutraFix). The aboveground plant tissue was assessed for boron presence and crude protein content. However, several samples did not have enough biomass for analysis and again some replications were combined, limiting our analysis. The mean boron content of control western wheatgrass plants was 24.6 ppm (n = 7), and did not differ for western wheatgrass plants treated with NutraFix which was 80.9 ppm (n = 6) (p = 0.194; Fig. 9). The mean boron content of control bluebunch wheatgrass plants was 10.9 ppm (n = 2), and for bluebunch wheatgrass plants treated with NutraFix was 31.2 ppm (n = 1) (Fig. 9). The mean crude protein content of control western wheatgrass plants did not differ (p = 0.397), with a mean of was 8.4 (Fig. 10). The mean crude protein content of control bluebunch wheatgrass plants was 6.5%, and for bluebunch wheatgrass plants treated with NutraFix was 4.9% (Fig. 10). The only soil characteristic that differed between the non-treated control and NutraFix treatments was an increased boron content, by 0.5 ppm, in the NutraFix plots (Table 1).
Research Outcomes
Our preliminary findings suggest that boron (NutraFix) could be reducing seed germination of both non-native and native grass species at low concentrations. This phytotoxic activity could be contributing to NutraFix’s ability to reduce annual grass cover over time. We also found that perennial grasses treated with NutraFix or boron were accumulating boron in their aboveground tissues, however, not at a rate likely dangerous to cattle or other ruminants. NutraFix appeared to increase crude protein content in perennial grasses in our controlled setting, but not four years post application in the field. Boron also reduced above and belowground biomass of perennial grasses in a controlled setting and also caused chlorosis of leaf tissues.
While we continue our research, we are especially focusing on the logistics of converting application rates between field and controlled settings and how soil characteristics may be influencing the impacts of NutraFix/boron.
We believe having more information about how this product is working in controlled settings will aid producers and land managers when contemplating the use of this product in their integrated weed management approaches. Having a well-diversified approach to weed management helps increase the sustainability of agricultural productions, but it is important to have a strong understanding of how each potential tool is impacting both the target weed and desired vegetation.
Education and Outreach
Participation Summary:
Objective 5a: Addressing this objective will include summarizing the outcomes and implications of our studies into extension fact sheets and short videos (1-3 minutes). These fact sheets and videos will highlight results from our research and translate those results into management implications. Fact sheets will be shared in-person through events like scientific meetings and field days. Videos will be published on research websites, MSU extension pages, and social media in an attempt to reach a wider audience. We plan to post updates and outcomes as part of Dr. Mangold’s Monthly Weed Post (https://www.montana.edu/extension/invasiveplants/extension/monthly-weed-posts/) and Dr. Rew’s research website (https://www.montana.edu/plantinvasions/).
Objective 5b: Addressing this objective will include interactions with cooperating land managers and producers along with other interested individuals attending scientific meetings and field days organized by extension agents at Montana State University. Presentations at local (Montana Weed Control Association) and regional (Society of Range Management, Western Society of Weed Management) scientific meetings will allow us to reach a diverse audience. These conferences each draw 200 to 1600 attendees including producers, educators, public land managers, policy makers, and researchers. Research addressing the management and impacts on invasive annual grasses has been of great interest to these audiences in recent years. All the co-PIs have presented at these meetings in the past, and we believe that they would be a good opportunity to present these findings and to build relationships with influential figures in the field and extend our outreach. These meetings also serve as a venue for me, as the graduate student, to present my research, gaining important science communication skills for advancing my career in invasive plant research and management. These meetings are typically held in February and March, so we plan to present the findings of this research in the spring of 2025.
Field days at our research sites will be held after the research has been conducted in the summer of 2025. We will work closely with Dr. Mangold, an extension specialist in rangeland invasive plant management to organize these events and facilitate meetings with managers and producers. These meetings will allow for visualization of the impacts NutraFix is having on native and non-native range species along with the opportunity to disseminate handouts with summarized results and for producers to ask questions.
Objective 5c: Addressing this objective will include the preparation of one to two papers for peer-reviewed publication. We believe the information we find about how NutraFix impacts seed germination and seedling establishment would be suited to the audiences of a journal like Weed Science. Where the second portion of our project focusing on how NutraFix impacts soil properties and forage quality may be best suited for a journal like Rangeland Ecology and Management. Publishing the research in these journals will help interested scientists, managers, and producers learn more about the impacts of NutraFix on native and non-native range species, soil health, and the potential it has for weed management. Manuscripts will be submitted in the second year of the project.
Objective 5a: Due to the unfortunate circumstances of requiring high amounts of biomass for forage analyses we will try again this summer, and the delay in the greenhouse rental is also being addressed. We will produce educational products in the fall of 2025.
Objective 5b: A field day is planned for June 4th, 2025, at the Red Bluff Research Ranch, where I along with other researchers from MSU will share their results on a variety of annual grass research topics. Producers and land managers from the surrounding counties are expected to attend. Data from this project was not available to be presented at scientific conferences this spring (2025), but an application has been submitted to present this data at the Montana Weed Control Annual conference in 2026.
Objective 5c: Not enough data has been collected to start preparing a manuscript, but we plan to address this deficit this summer.