Flint Hills Research Articles

Sunset Over Flint Hill, 2023 by Hong Chun Zhang

Art is integrated into the Mayo Clinic environment. Since the original Mayo Clinic Building was finished in 1914, many pieces have been donated or commissioned for patients and staff to enjoy. Each issue of Mayo Clinic Proceedings features a work of art (as interpreted by the author) that is displayed in a building or on the grounds of Mayo Clinic campuses.

Assessment of Oklahoma Phlox (Phlox oklahomensis: Polemoniaceae) in the Gypsum Hills of Northwestern Oklahoma and Southern Kansas

Phlox oklahomensis Wherry, Oklahoma phlox, occurs within the tall grass prairie of the southern Flint Hills of Kansas, and other populations occur within the southern mixed grass prairie of the Gypsum Hills of northwestern Oklahoma and southern Kansas. The first census of Oklahoma phlox in northwestern Oklahoma and southern Kansas was conducted over a three-year period (1980-1982). The second and third censuses occurred approximately 20 years after the first census, in 2002 and 2003. Since the 1980s two major wildfires and several droughts have occurred throughout its distribution range. The goals of this research were to compare the 1980-1982 census and the 2002 and 2003 censuses of Oklahoma phlox to censuses conducted in 2020 and 2021 and assess the current status of the species. In addition, we used a geographic information system (GIS) to identify factors that influence the likelihood of finding Oklahoma phlox in the region. The final census found that the occurrence of Oklahoma phlox has not changed significantly over the last 40 years. Populations thrive in areas where the fire interval is >5 years, and it commonly occurs on the upper elevations of the landscape on hilltops and/or ridges where the slope is > 7%. Although plants were observed on all landscape exposures, populations occur more frequently on west and northwest facing slopes. The authors recommend an S3 ranking for Oklahoma phlox.

Spatial and physical characteristics of bison wallows in the Flint Hills of Kansas

AbstractBison have long been considered a keystone species of North American prairies, increasing plant and animal diversity through a number of unique behaviors. One such behavior is wallowing, in which the repeated rolling of bison in the same spot leads to the formation of small, shallow, oval depressions called wallows. The objective of this study was to characterize spatial and physical attributes of bison wallows at the Konza Prairie Biological Station, a tallgrass prairie preserve in northeastern Kansas. We used aerial imagery from two different years (2011 and 2019) to assess the abundance and spatial distribution of these wallows in relation to fire frequency, elevation, and slope. We also recorded physical characteristics (2020) for a randomly selected subset of wallows and analyzed these data in relation to the same landscape features. Results from the analysis of the aerial images indicated that wallows were more abundant in areas characterized by combinations of more frequent burning, higher elevations, and little or no slope. In the 2020 physical measurements, we found that wallows were smaller in areas burned more often and shallower at higher elevations, particularly when located on grazing lawns. Terrestrial plants were found in approximately 72.1% of the wallows that were physically sampled, and their prevalence increased with increasing slope. We found some quantity of aquatic plants in approximately 7.1% of the sampled wallows. The probability of finding aquatic vegetation in wallows was higher on grazing lawns and in areas burned less frequently, particularly every 20 years. This study enhances the understanding of the distribution of wallows and their physical characteristics as a type of disturbance that could alter relationships within grassland communities.

Quantifying Prescribed-Fire Smoke Exposure Using Low-Cost Sensors and Satellites: Springtime Burning in Eastern Kansas.

Prescribed fires (fires intentionally set for mitigation purposes) produce pollutants, which have negative effects on human and animal health. One of the pollutants produced from fires is fine particulate matter (PM2.5). The Flint Hills (FH) region of Kansas experiences extensive prescribed burning each spring (March-May). Smoke from prescribed fires is often understudied due to a lack of monitoring in the rural regions where prescribed burning occurs, as well as the short duration and small size of the fires. Our goal was to attribute PM2.5 concentrations to the prescribed burning in the FH. To determine PM2.5 increases from local burning, we used low-cost PM2.5 sensors (PurpleAir) and satellite observations. The FH were also affected by smoke transported from fires in other regions during 2022. We separated the transported smoke from smoke from fires in eastern Kansas. Based on data from the PurpleAir sensors, we found the 24-hr median PM2.5 to increase by 3.0-5.3μgm-3 (based on different estimates) on days impacted by smoke from fires in the eastern Kansas region compared to days unimpacted by smoke. The FH region was the most impacted by smoke PM2.5 compared to other regions of Kansas, as observed in satellite products and in situ measurements. Additionally, our study found that hourly PM2.5 estimates from a satellite-derived product aligned with our ground-based measurements. Satellite-derived products are useful in rural areas like the FH, where monitors are scarce, providing important PM2.5 estimates.

Investigating the Climate Mitigation Performance of A Green Roof System in the Flint Hills Ecoregion, USA

Rooftop green infrastructure enhances sustainable urban development by reducing atmospheric CO2 as carbon is sequestered in plants and substrates. However, it is uncertain what substrate types, depths, and plant combinations sequester the greatest amounts of carbon in green roofs across different ecoregions, including the U.S. Great Plains. This research sought to evaluate carbon sequestration potential of two experimental green roof beds of 10 cm (4 in) and 20 cm (8 in) and two substrate types in Manhattan, Kansas, USA. Microbial and root biomass and their interactions were measured as early indicators of changes in soil organic carbon (SOC). Soil and root biomass samples were taken from beds of two depths with two substrates (K and R) and three plant communities (all sedum, sedum and grass, and native grasses and forbs) for a total of 48 plots. Microbial biomass was measured by phospholipid fatty acids (PLFA) analysis in 2019 and root biomass in 2020. Root biomass and microbial biomass was greater in native grass in shallower beds. Shallower beds can partially offset the need for deeper beds and should perform well in mitigating climate change if beds are irrigated during very dry periods.

The Effects of Seasonal Prescribed Burning on Flint Hills Dung Beetle (Scarabaeinae) Populations

The Effects of Seasonal Prescribed Burning on Flint Hills Dung Beetle (Scarabaeinae) Populations

Long-Term Effects of April, August, or October Prescribed Fire on Yearling Stocker Cattle Performance and Native Rangeland Plant Composition in the Kansas Flint Hills

Long-Term Effects of April, August, or October Prescribed Fire on Yearling Stocker Cattle Performance and Native Rangeland Plant Composition in the Kansas Flint Hills

Consequences of drought for grassland songbird reproduction

AbstractAbiotic stressors can be major sources of selection, resulting in diverse demographic responses operating via multiple direct and indirect mechanisms. However, unusual weather events are notoriously difficult to study due to their spatial and temporal unpredictability. A severe drought affected the Flint Hills of Kansas in 2018, occurring during the ongoing population‐level studies of three species of declining grassland songbirds: Eastern Meadowlarks (Sturnella magna), Grasshopper Sparrows (Ammodramus savannarum), and Dickcissels (Spiza americana). We compared nest survival, nest initiation date, and potential behavioral drivers of reproductive differences (i.e., nest orientation, investment) between the 2018 drought year and 2–6 years of average‐to‐wet years. Nest initiation in the drought year was concentrated early in the season, suggesting that birds did not renest or attempt second broods. The two species that build domed nests shifted the orientation of nest entrances away from early morning sun and toward the direction of prevailing winds in the drought year. Multiple nest‐level metrics of investment and success were similar in drought and nondrought years. These results suggest that demographic changes during droughts can reflect both direct responses and may also involve biotically mediated trophic consequences.

The lasting legacy of glacial landscape dynamics: Capturing the transport of boulder armor and hillslope retreat with geochronology in the Flint Hills of Kansas

We present new geochronological data derived from hillslope boulder armor in the Flint Hills in northeastern KS, United States, that provides insights into the rates and timing of lateral retreat in this landscape. Our results show that the surfaces of these limestone boulders date back to the Pleistocene era, well within the last glacial period. We also found that there is a significant increase in the ages of hillslope armor with increasing distance downslope from the modern limestone bench, the source of the boulders. Based on the age-distance relationship of the boulders, we estimate the rate of lateral retreat in this landscape to be 0.02 mm/yr, which falls between the geometrically estimated retreat rates based on calculated denudation rates of the Flint Hills region. We propose that the cooler temperatures and higher effective moisture due to less efficient evapotranspiration during the late Pleistocene period resulted in more effective freeze-thaw and transport processes, such as creep due to soil expansion and contraction. The production and transport of new boulder armor would then have effectively ceased once the climate transitioned to warmer conditions during the Holocene. Our findings suggest that the boulder armor we observe on the soil mantled hillslopes today are relict features from before the LGM-Holocene transition. These results provide important insights into the long-term evolution of these ubiquitous layered sedimentary landscapes.

423 Effects of Prescribed Fire Timing on Stocker Cattle Performance and Native Plant Species Composition in the Kansas Flint Hills

Abstract Ranchers in the Kansas Flint Hills apply spring-season prescribed fire to improve growth performance of yearling stocker calves, increase native warm-season grass production, and reduce encroachment of woody and invasive plant species. Shifting prescribed fire application from spring (i.e., April) to late summer (i.e., August) or early fall (i.e., September) can reduce Sericea lespedeza infestation, increase native forb diversity, and improve air quality by distributing smoke produced from burning the Flint Hills throughout the year. Effects of late-summer or early-fall prescribed fire on yearling grazing cattle performance is unknown; therefore, our objective was to determine the impact of prescribed-fire timing on growth performance of yearling grazing cattle and plant community characteristics in the Kansas Flint Hills. Over a four-year period, 18 pastures were grouped by watershed and each watershed was assigned to one of three prescribed-fire treatments (24 pastures/treatment): spring (9 April ± 5.1 d), summer (23 August ± 4.9 d), or fall (29 September ± 8.7 d). Burn treatments were applied in years 1, 2, and 3 but were not applied in year 4 due to unfavorable burn conditions. Over 4 consecutive grazing seasons, 1,416 yearling calves (initial BW = 304 ± 49.6 kg) were grazed from May to August following prescribed fire application. Calves were grazed for 90 d at a targeted stocking density of 280 kg live-weight· ha-1. A permanent 100 m transect was established in each pasture and was used to determine plant species composition and soil cover using a modified step-point method. Plant species composition was determined annually in June. Data were analyzed as a completely random design using a mixed model. The final model contained treatment as a fixed effect and year and pasture within treatment as random effects. Average daily gain (ADG) tended to be greater (P = 0.06) for spring-burned pastures compared with fall-burned pastures, whereas ADG for summer-burned pastures were intermediate. Proportions of bare soil were greater (P < 0.01) in spring-burned pastures compared with summer- and fall-burned pastures. Conversely, proportions of litter on the soil surface were greatest (P < 0.05) in summer, intermediate (P < 0.05) in fall, and least (P < 0.01) in spring-burned pastures. Total grass, native grass, total forb, and native forb basal cover did not differ (P ≥ 0.13) among treatments. Conversely, basal cover of nectar-producing forbs was greater (P < 0.01) in fall-burned pastures compared with spring- and summer-burned pastures. Overall, fall prescribed-fire tended to reduce ADG; however, stocker cattle growth performance and native rangeland plant composition was similar between spring- and summer-burned pastures.

Simulation of the Impact of Rangeland Management Strategies on Soil Health, Environmental Footprint, Economic Impact, and Human-Edible Nutrient Conversion from Grasslands in the Central and Northern Great Plains of the United States

The objective of this study was to determine the impact of combinations of management practices on the sustainability of rangelands in different ecoregions across the Great Plains. Six study sites were selected in Kansas, Nebraska, Wyoming, Montana, and South Dakota, encompassing the Flint Hills, High Plains, and Sandhills ecoregions. Twelve rangeland management scenarios were developed from combinations of stocking density (light, moderate, heavy), grazing management (continuous, rotational), and fire regime (no burn, spring burn) along with a no-management scenario. Each scenario was simulated at each site using established computer models: Agricultural Policy/Environmental eXtender model, Integrated Farm System Model, and Impact Analysis for Planning. Additionally, human-edible nutrient conversion was computed. A sustainability index was developed to encompass the three sustainability pillars (i.e., environmental, economic, and social) into a single value. Unmanaged rangelands generally had less soil (20%), nitrogen (30%), and phosphorus (50%) losses, although this was not consistent across ecoregions, and similar or greater soil carbon deposition than grazed rangelands. There was an interaction among stocking density, grazing management, fire regime, and ecoregion for many indicators of soil health, greenhouse gas emissions, economic activity, and human-edible nutrient conversion. The scenarios with the greatest overall sustainability index value had moderate to high index values for each of the three pillars (people, planet, profit). In conclusion, the ranking of rangeland management practices based on sustainability indicators was inconsistent across ecoregions, indicating that the optimal management system to improve sustainability of rangelands is not the same for all ecoregions.

Finding on Convergence of the Flint Hills and Cookson Hills Series based on a Summation Formula of Adamchik and Srivastava involving the Riemann Zeta Function

This article showcases significant progress in solving two renowned problems in the calculus of series: the Flint Hills and Cookson Hills series. For almost twenty years, a long-standing question has remained unanswered in regard to their convergence. Mainly, proving the convergence of the Flint Hills series would significantly impact the redefinition of the upper bound for the irrationality measure of the number π. One of the results presented in this article is that the Flint Hills series converges to 30.3144... which leads to a redefinition of the upper bound for the irrationality measure of π, specifically μ(π)≤ 2.5. This work proposes a transformation that solves the mystery of the Flint Hills and Cookson Hills series. It is based on a summation formula developed by mathematicians Adamchik and Srivastava. By leveraging a specialized series supported by the Riemann zeta function, this approach successfully transforms the original Flint Hills and Cookson Hills series into novel convergent versions with unique significance. The resulting sequences linked to these series are positive and bounded and satisfy convergence. Moreover, this article extends the Flint Hills series when the cosecant function has an arbitrary complex argument n+iβ, with i=√(-1), establishing a new series representation based on the polylogarithm 〖Li〗_3 (e^i2k), with k=1,2,3,…, e the Euler’s number, which bears resemblance to the famous integral of the Bose-Einstein distribution as a relevant finding. This is a never-seen-before link between the Flint Hills series and polylogarithms. Furthermore, a relationship between the Apéry constant and the Flint Hills and Cookson Hills series has been established. This article presents a significant breakthrough in the calculus of series by introducing a new method based on the Riemann Zeta function and logarithmical expressions derived from the Adamchik and Srivastava summation formula. The novel approach extends the analysis of convergence criteria for series, addressing ambiguous cases characterized by abrupt jumps. Thus, the Flint Hills series converges to 30.3144... and the Cookson Hills series to 42.9949... as proved in this article.

Seasonal emission factors from rangeland prescribed burns in the Kansas Flint Hills grasslands

Operational-sized prescribed grassland burns at three mid-West U.S. locations and ten 1-ha-sized prescribed grassland burns were conducted in the Flint Hills of Kansas to determine emission factors and their potential seasonal effects. Ground-, aerostat-, and unmanned aircraft system-based platforms were used to sample plume emissions for a range of gaseous and particulate pollutants. The ten co-located, 1-ha-sized plots allowed for testing five plots in the spring and five in the late summer, allowing for control of vegetation type, biomass loading, climate history, and land use. The operational-sized burns provided a range of conditions under which to determine emission factors relevant to the Flint Hills grasslands. The 1-ha plots showed that emission factors for pollutants such as PM2.5 and BTEX (benzene, toluene, ethylbenzene, and xylene) were higher during the late summer than during the traditional spring burn season. This is likely due to increased biomass density and fuel moisture in the growing season biomass resulting in reduced combustion efficiency.

A Culture of Fire: Identifying Community Risk Perceptions Surrounding Prescribed Burning in the Flint Hills, Kansas

In the Flint Hills region of eastern Kansas, there is a long tradition of spring prescribed burns. However, air quality concerns in downwind communities have sparked conversation regarding the environmental and social impacts of these burns. This study aimed to identify the risk perceptions associated with prescribed burns using two theoretical frameworks: the social amplification of risk framework and the protective action decision model. In April 2022, we conducted 18 in-depth, semi-structured interviews with Flint Hills community members from different social stations. Participants identified several benefits of prescribed burns: cattle production gains, invasive species management, prairie ecological health maintenance, and wildfire prevention. Some participants viewed prescribed burning as a protective response. However, risk perceptions differed between rural and urban participants: rural community members were primarily concerned with prescribed fires that went out of control, while those in downwind cities were primarily concerned with smoke exposure. Participants sometimes used protective actions to mitigate their risks, but also explained the complexities of changing burn practices that are integral to the local culture, economies, and greater society. Additionally, formal communication of health and safety risks from prescribed burns is not uniform across Kansas counties. We therefore recommend systematic county and statewide communication of burn practices and protective behaviors. Understanding community perceptions of the risks and effects of prescribed burns, and any protective actions taken, can inform how professional communicators approach burning in similar agricultural and ranching communities.

Effects of Prescribed-Fire Timing on Stocker Cattle Performance, Forage Biomass Accumulation, and Native Plant Species Composition

Objective: The objective of this experiment was to document the effects of prescribed-fire timing on stocker cattle performance, forage biomass accumulation, soil cover, and plant species composition in the Kansas Flint Hills. Study Description: A total of 1,416 yearling stocker cattle were assigned to one of three prescribed-burn treatments: spring (April 9 ± 5.1 days), summer (August 23 ± 4.9 days), or fall (September 29 ± 8.7 days) over a 4-year period. Calves were grazed from May to August for 90 days. Individual body weights were recorded at the beginning and end of the grazing season. Native plant composition and soil cover were evaluated annually using a modified step-point method, and forage biomass was measured biannually. The Bottom Line: Flint Hills ranchers can employ late-summer prescribed fires to manage sericea lespedeza (Lespedeza cuneata) infestations without negatively impacting stocker cattle growth performance, forage biomass accumulation, or native rangeland plant species composition.

Measuring Smoke Emissions from Prescribed Rangeland Burning in the Flint Hills Region Using Unmanned Aircraft Systems

Highlights Smoke samples collected with UAS during rangeland prescribed burns were used to develop representative smoke emission factors for rangeland fires. The head fire emission factors of PM2.5 and NOx were consistent with the low end of the range of flaming emission factors in the literature. The combination of high air temperatures and high absolute humidity resulted in higher levels of PM2.5 and O3 in smoke. Abstract.Prescribed burning is an ecological process critical to maintaining and improving rangeland ecosystems. Smoke impacts related to prescribed burning have been the subject of intense discussion and public debate. The objectives of this study were to collect accurate smoke emissions data using unmanned aircraft systems (UAS) and use the data to develop smoke emission factors representative of prescribed rangeland fires in the tallgrass prairie Flint Hills region of Kansas and Oklahoma. The emission factors will be used to improve the input parameters used in smoke modeling tools. Four prescribed burns on unique burn units were sampled for this study. Smoke emission factors were determined using the carbon mass balance method. Average emission factors for head fires were: PM2.5, 11.3±10.8g/kg fuel; NOx as NO, 1.4±0.9 g/kg fuel; CO2, 1569±28 g/kg fuel; CH4, 6.8±4.3 g/kg fuel; NMHC as propane, 3.3±2.5 g/kg fuel; and VOC as propane, 4.5±3.5 g/kg fuel. Compared with head fires, back fires tended to produce lower emissions of PM2.5 but higher emissions of NOx and VOC. Green, high-moisture vegetation present during the growing season fires in September resulted in a larger head fire PM2.5 emission factor compared to April fires. Generally, the combination of high air temperature and high absolute humidity resulted in high PM2.5 and O3 in smoke. Conducting prescribed fires under conditions of cool air temperature and low absolute humidity can reduce the generation of PM2.5 and O3 in smoke, as long as these conditions fall within the prescribed range for the burn. Keywords: Carbon mass balance, Drone, Fire, Grass, Ozone, Pasture, Prescribed burning, Rangeland management, Rangelands, Smoke emission factor, Tallgrass prairie, Unmanned aircraft system.

Effects of late-season sheep grazing following early-season steer grazing on population dynamics of sericea lespedeza in the Kansas Flint Hills

Mature ewes were used in a 4-yr study to evaluate effects of intensive late-season sheep grazing on vigor of sericea lespedeza in native tallgrass prairie. Pastures (N = 8; 31 ± 3.6 ha) infested with sericea lespedeza (initial basal frequency = 1.4%) were assigned randomly to one of two treatments: early-season beef steer grazing (1.1 ha/steer; initial BW = 258 ± 34 kg) from April 15 to July 15 followed by no grazing for the rest of the year (control; STR) or steer grazing from April 15 to July 15 followed by intensive grazing by mature ewes (0.2 ha/ewe; SHP) from August 1 to October 1. Ewes (initial BW = 65 ± 3.1 kg) were assigned randomly to graze four of eight pastures; remaining pastures were not grazed from August 1 to October 1. Vegetation responses to treatment were measured along four permanent 100-m transects in each pasture. Herbivory on sericea lespedeza was monitored weekly in each pasture from July 21 to October 7. Herbivory on sericea lespedeza in SHP and STR after steer grazing and before sheep grazing was not different (P = 0.51). In contrast, sericea lespedeza herbivory following sheep grazing was greater (P < 0.01) in SHP than in STR. Herbivory of individual sericea plants was greater (P < 0.01) in SHP than in STR by the end of week 1 of the sheep-grazing period (10.6% vs. 0.5%); moreover, herbivory on sericea lespedeza steadily increased (P ≤ 0.01) such that 92.1% of sericea lespedeza plants were grazed in SHP compared to 1.4% in STR by week 8 of the sheep-grazing period. Whole-plant DM weight of sericea lespedeza at dormancy was less (P < 0.01) in SHP than in STR. Additionally, annual seed production by sericea lespedeza was less (P < 0.01) in SHP than in STR (114 vs. 864 seeds/plant). Pasture forage biomass was not different (P = 0.76) between SHP and STR after the steer-grazing period. Conversely, STR had more (P < 0.01) residual forage biomass than SHP at the end of the sheep-grazing period. Growth performance of beef steers grazing from April 15 to July 15 annually was not different (P ≥ 0.59) between treatments. Our results were interpreted to suggest that intensive late-season grazing by sheep decreased vigor of sericea lespedeza. Late-season sheep grazing decreased forage biomass by 904 kg DM/ha compared with late-season rest; however, residual biomass was adequate to prevent soil-moisture loss and erosion during the dormant season.

Optimum Weather Conditions for Prescribed Burning in the Flint Hills Region

Highlights The subjectivity of landowner decisions in prescribed burning was influenced by solar radiation and relative humidity. Landowners preferred to burn when there was less cloud cover, which promoted O3 generation. Proposed optimum weather conditions will reduce the smoke impact on O3. Abstract. Land managers use weather conditions to determine when meteorological and fuel conditions are suitable for prescribed burning. The objectives of this study were: 1) to characterize meteorological parameters’ sensitivities and identify the influential weather parameters connected to daily fire activities; and 2) to identify optimum weather conditions that are practical for mitigating the smoke impact associated with prescribed fires in the Flint Hills region. Machine learning techniques using random forest (RF) with Shapley additive explanation (SHAP) values and Pearson correlation were used to identify the relative importance of weather variables and their impact on landowner burn decisions in the Flint Hills region based on historic data from 2003-2019. Results showed that less cloud cover demonstrated superior predictive power in landowner decisions for prescribed burning and largely resulted in elevated ambient ozone (O3). We found out that six days per burning season on average provided the proposed optimum weather conditions, where cloud cover ranged from 10+ to 55%. However, 62% of the total burned area occurred when the cloud cover was less than 10+% during 2003-2019. By changing the current burning occurrence to the proposed optimum weather conditions in our study, the probability of 70+ ppb O3 occurrence could be reduced from 35% to 9% on heavy fire days. Keywords: Cloud cover, Optimum weather conditions, Ozone, Prescribed burning.

A 6-yr evaluation of prescribed-fire timing on yearling cattle growth performance and plant community dynamics on native tallgrass prairie in the Kansas Flint Hills

Abstract A 6-yr experiment was conducted to determine the effects of prescribed-fire season on stocker cattle growth performance and rangeland plant community characteristics in the Kansas Flint Hills. Eighteen pastures were grouped by watershed and each watershed was randomly assigned to 1 of 3 prescribed-fire treatments: spring (11 April ± 5.7 d), summer (25 August ± 6.2 d), or autumn (2 October ± 9.0 d). All burns were applied prior to grazing in years 1, 2, 3, and 5; however, no burns were applied in year 4 because of unfavorable burn conditions. Over 5 consecutive grazing seasons, 1,939 yearling stocker calves (initial BW = 281 ± 58.9 kg) were grazed from May to August at a targeted stocking density of 280 kg live-weight + ha−1. Beginning in June of 2018 (pretreatment), a permanent 100-m transect was established in each pasture and was used to determine plant-species composition using a modified step-point method. Forage biomass accumulation and root carbohydrate concentrations of 4 native tallgrass plant species were also measured. All data were analyzed as a completely randomized design using a mixed model. Average daily gain (ADG) was 0.05 to 0.07 kg greater (P = 0.02) for calves grazing spring-burned pastures compared with calves grazing summer- or autumn-burned pastures; however, ADG did not differ (P ≥ 0.55) between calves assigned to the summer or autumn prescribed-fire treatments. Basal cover of all graminoids and all forbs did not differ (P ≥ 0.30) among prescribed-fire treatments; however, basal cover of C3 grasses tended (P = 0.06) to be greater while basal cover of C4 grasses tended (P = 0.08) to be less in autumn-burned pastures compared with spring-burned pastures. Forage biomass accumulation did not differ (P = 0.58) among treatments. In addition, root starch or root water-soluble carbohydrate concentrations in big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), Indiangrass (Sorghastrum nutans), or purple prairieclover (Dalea purpurea) did not differ (P ≥ 0.26) among prescribed-fire treatments. Overall, we interpreted these data to suggest that prescribed-fire timing had small influences on yearling stocker cattle growth performance and rangeland plant composition but did not influence forage biomass accumulation or root carbohydrate concentrations of key native tallgrass plant species in the Kansas Flint Hills.

Effects of Biuret and Lasalocid (Bovatec) Inclusion into a Commercial Mineral Supplement on Growth Performance of Yearling Calves Grazing in the Kansas Flint Hills

Objective: The objective of this experiment was to measure the effects of non-protein nitrogen (NPN; i.e., biuret) or NPN + ruminal modifier (i.e., biuret + lasalocid) inclusion in a commercial mineral mix on growth performance of yearling beef calves grazing in the Kansas Flint Hills.