Beef production in the Southern Great Plains (SGP) has always been a challenge. Periods of extreme heat and drought, changing markets, etc. have always challenged beef producers in the SGP. In the future, higher temperatures and greater frequency of drought are predicted and for beef production to continue to survive and thrive in the SGP new technologies must be developed and adopted. In 2013, research and extension faculty from Kansas State University, Oklahoma State University, University of Oklahoma, USDA-ARS, Tarleton State University and the Noble Foundation teamed together and received the USDA-NIFA Coordinated Agricultural Project Grant, “Resilience and vulnerability of beef cattle production in the Southern Great Plains under changing climate, land use and markets.” Our Great Plains Grazing team’s overall mission is to answer research questions and deliver extension programming about the impacts of climate variability and climate change on the grazing portion of the beef industry. Our project goals are to: (1) better understand vulnerability and enhance resilience of beef-grazing systems in a world of increased climate variability, dynamic land-use, and fluctuating markets, and (2) safeguard regional production while mitigating the environmental footprint of agriculture. Our overall hope is to increase resilience to climate variability and climate change and sustain the productivity of beef grazing systems in the Southern Great Plains. The research presented below is a summary of results of research that has been conducted.
Cosmic-ray Soil Moisture Observing Systems (COSMOS) in Grazing-CAP fields at El Reno, Oklahoma
Patrick J. Starks, Rajen Bajgain, Jeffrey Basara, Jean L. Steiner, and Xiangming Xao
Soil water content (SWC), especially over large areas, is an important variable needed by hydrological, meteorological, climatological, agricultural, and environmental scientists. Point measurements of SWC are impractical to obtain over extensive areas; thus, methods that provide real-time, hectare-scale measurements are needed. The COSmic-ray Soil Moisture Observing System (COSMOS) is such a method. Three of these systems were deployed within fields at the USDA-ARS Grazinglands Research Laboratory (GRL), in El Reno, OK. Two were located in Grazing-CAP fields and the other in a winter wheat field. The objectives of this report are to describe the field settings in which the COSMOS sensors are deployed and to provide a first-look at the soil moisture time series data from the COSMOS sensors. Comparison of the data from the three sites showed similar wetting and drying cycles among the fields. Comparison of measured in situ and COSMOS SWC verified that other environmental factors (e.g., atmospheric humidity) influence the COSMOS values. Once calibrated and fully vetted, the COSMOS data from the Grazing-CAP sites will provide useful input to the CAP lifecycle analysis as well as input to other CAP projects.
Hyperspectral Canopy Reflectance as a Predictor for Root Concentrations of Nitrogen and Carbon in Native and Non-native Grass Species
Trey Scott, Brekke L. Peterson and Patrick Starks
Land managers, scientists, and crop professionals need real-time, inexpensive, and labor-saving methods to determine below-ground biomass and potential carbon (C) and nitrogen (N) inputs of that biomass. Remote sensing is a non-destructive tool that monitors vigor of vegetation and has been used to assess forage quality. A study was conducted at the USDA-ARS Grazinglands Research Laboratory, El Reno, OK in non-native, Old World Bluestem (Bothriochloa sp.) and native, tallgrass prairie to: 1) determine N and C concentrations of roots of non-native and native pasture, 2) determine if canopy hyperspectral reflectance data can produce a usable equation for non-destructive determination of total root C and N. Hyperspectral canopy reflectance was measured bi-weekly using an ASD FieldSpec FR radiometer. Destructive canopy and root samples were acquired immediately after the hyperspectral data were collected. Sampling occurred at toe-, mid- and upper-slope positions along four parallel and widely-spaced transects. Canopy and roots were separated, oven-dried at 65oC for 48 hr, ground and total C and N concentrations determined. Canopy reflectance and root concentrations of C and N were statistically analyzed using partial least square. Initial results indicate that prediction of root C and N from hyperspectral canopy reflectance is moderate (R2=0.65). However, further study is needed to determine if this is an appropriate non-destructive method. Implications of this research could lead to quicker determination of belowground inputs to soil carbon and nitrogen cycles and provide a better understanding of perennial ecosystem services.
Assessment of Microbial Biomass Carbon and Nitrogen of Native and Non-Native Perennial Pasture Soil using Hyperspectral Data
Keira Auld, Brekke L. Peterson and Patrick J. Starks
Soil microbial biomass carbon and nitrogen (MBC/MBN) are integral parts of soil organic matter, and if left out of nutrient calculations may suggest increased need of fertilizer resulting in increased production costs and chemical runoff. Timely and cost-effective methods are needed to assess MBC and MBN, and remote sensing techniques may provide such a solution. A study was conducted at the USDA-ARS Grazinglands Research Laboratory Old World Bluestem (Bothriochloa sp.) and native, tallgrass pastures to: 1) determine MBC/MBN content of native and non-native perennial pasture soils, and 2) correlate MBC/MBN values with hyperspectral reflectance data of dried, ground soils to determine if reflectance data can be used to determine MBC/MBN content of soil. Bi-weekly soil sampling (0-15cm) occurred at toe-, mid- and upper-slope positions along four parallel and widely-spaced transects. Each soil sample was processed for MBC/MBN using standard techniques. Bulk unfumigated and fumigated soils were dried at 65°C for 24 hr, ground to pass a 2mm sieve and hyperspectral reflectance data were obtained using an ASD FieldSpec FR radiometer. Soil reflectance and MBC/MBN concentrations were statistically analyzed to determine if soil reflectance could be used for predicting MBC/MBN. Initial results indicate that hyperspectral soil scanning is a promising method for determining soil MBC and MBN concentrations (R2=0.65). Further study is needed to determine if this will be a suitable tool to determine MBC/MBN with the precision needed for management. Implications of this research could lead to real time soil fertility decision making reducing input cost and loss of C and N to the environment.
Seasonal Greenhouse Gas Emissions and Soil Nutrient Cycling in Semi-Arid Native and Non-Native Perennial Grass Pastures
Brekke L. Peterson, Miguel Andres Arango Argoti, Charles Rice and Jean Steiner
Previous research indicates that there is a difference btween native and non-native grass species concerning greenhouse gas [GHG, (carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O))] emissions from soil. This information could help establish best management practices to mitigate GHGs and store soil C and N. We hypothesized that the magnitude of labile soil carbon (C) and nitrogen (N) would increase with soil moisture followed by an increase in GHG emissions, and that this increase would be greater in non-native pasture soils as compared to native pasture soils. A study at the USDA-ARS Grazinglands Research Laboratory, El Reno, OK was conducted to: 1) determine seasonal soil C and N content and 2) obtain seasonal GHG emissions of soils under native and non-native perennial grasses. Bi-weekly sampling of GHG emissions from stationary static chambers and soil C and N (0-15cm) occurred in native and non-native perennial pastures in replicates of five. Greenhouse gas samples were analyzed for CO2, CH4 and N2O on a gas chromatograph. Soil water content (SWC), physical properties and labile C and N were determined using standard methods. Initial results indicate that the magnitude of CO2 and N2O were proportional to SWC, and CH4 assimilation was lower in semi-arid soils under native perennial grasses compared to soils under non-native grasses. Soils under non-native grasses had higher magnitudes of CO2 and N2O, while CH4 assimilation was similar to soil under native grasses during warmer seasonal trends where moisture was limited. The implication of this research indicates that GHG fluxes from soils in semi-arid environments are likely altered by abiotic drivers.
Daily Time Series Evapotranspiration Maps for Oklahoma and Texas Panhandle
P.H. Gowda, G. Paul, T.H. Marek, J. Basara, J.L. Steiner, Y. Zhou, and X. Xiao
Evapotranspiration (ET) is an important process in ecosystems’ water budget and closely linked to its productivity. Therefore, regional scale daily time series ET maps developed at high and medium resolutions have large utility in studying the food-energy-water nexus and managing water resources. There are efforts to develop such datasets on a regional to global scale but often faced with the limitations of spatial-temporal resolution tradeoffs in satellite remote sensing technology. In this study, we developed frameworks for generating high and medium resolution daily ET maps from Landsat and Moderate Resolution Imaging Spectroradiometer (MODIS) data, respectively. For developing high resolution (30-m) daily time series ET maps with Landsat TM data, the Two Source Energy Balance (TSEB) model was used to compute sensible and latent heat fluxes of soil and canopy separately. Landsat 5 (2000-2011) and Landsat 8 (2013-2014) imageries for path/row 28/35 and 27/36 covering central Oklahoma was used. MODIS data (2001-2014) covering Oklahoma and Texas Panhandle was used to develop medium resolution (250-m), time series daily ET maps with Surface Energy Balance System (SEBS). An extensive network of weather stations managed by Texas High Plains ET Network and Oklahoma Mesonet was used to generate spatially interpolated inputs of air temperature, relative humidity, wind speed, solar radiation, pressure, and reference ET. A linear interpolation sub-model was used to estimate the daily ET between the image acquisition days. Accuracy assessment of daily ET maps were done against eddy covariance data from two grassland sites at El Reno, OK. Statistical results indicated good performance by modeling frameworks developed for deriving time series ET maps. Results indicated that the proposed ET mapping framework is suitable for deriving daily time series ET maps at regional scale with Landsat and MODIS data.
Eddy covariance measurements of methane fluxes over grazed native and improved prairies in Oklahoma
P. Wagle, P. H. Gowda, J. L. Steiner2, X. Xiao1, J. Basara, J. Neel2, and B. Northup2
Although several studies have reported eddy covariance (EC) measurements at several tallgrass prairie sites to investigate the dynamics of carbon and water vapor fluxes, the EC measurements of methane (CH4) fluxes over grazed tallgrass prairie sites are lacking. CH4 fluxes were measured during the 2014 growing season over co-located native and improved tallgrass prairie sites in El Reno, Oklahoma. The major objective of this study was to quantify and compare the diel patterns and magnitudes of CH4 fluxes across the growing season between two prairie sites with periodic grazing by mobile cattle. The native prairie site behaved as a sink of CH4 over most diel time scales, with peak CH4 assimilation (approximately -0.15 µmol m-2 s-1) at around noon, from May to July and neutral in August in absence of grazed cattle. However, the site was a source of CH4 over most diel time scales during the grazing period (June 27-July11). Mean diel patterns of CH4 fluxes were not clearly different among months within the growing season at the improved prairie site during both grazing and non-grazing periods. The improved prairie site behaved as both sink and source of CH4 over diel time scales during grazing and non-grazing periods. However, the magnitudes of CH4 fluxes were higher during the grazing period (mostly ±0.10 µmol m-2 s-1 vs. ±0.02 µmol m-2 s-1). Major controlling factors of CH4 emissions or assimilations and the role of grazing cattle on the observed CH4 fluxes will be further investigated.
Forage Nutritive Value of Plant Samples Collected by Clipping or Rumen Evacuation
K.E. Turner, J.P.S. Neel, B.P. Munks, R.W. Todd, C.A. Moffet, P.H. Gowda, and J.L. Steiner
Knowing nutritive value and intake of forage by an animal is important to understand methane production data from individual animals in a grazed environment. Digestibility of forages is typically evaluated as the in vitro dry matter disappearance (IVDMD) using a clipped forage sample; however, beef cattle are selective grazers and do not consume the same plants as are obtained from clipping. The overall objective was to compare nutritive value, including IVDMD, of forage samples collected from a mixed native warm-season grass pasture by clipping or using a rumen-evacuation technique. There was a Month x Sample Method interaction (P < 0.001) for IVDMD, crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) and was dependent on the growth stage of the plants during the growing season. Overall when averaged over all sampling dates, forage samples collected from the rumen compared to clipping were higher (P < 0.001) in IVDMD % (59.8 ± 1.3 vs. 53.8 ± 0.7) and CP % (10.1 ± 0.3 vs. 5.7 ± 0.2), but lower in NDF % (72.4 ± 0.5 vs 77.7 ± 0.3) and ADF % (38.2 ± 0.6 vs.43.8 ± 0.4). Forage IVDMD data derived from rumen samples can better account for selectivity by grazing cows. This data will be coupled with data on fecal output to better predict forage intake by beef cows grazing native warm-season pastures in the southern Great Plains. In addition, this information will help in the understanding of methane inventories related to beef cattle production.
Pasture-scale methane emissions of grazing cattle
Richard W. Todd, Corey Moffet, James Neel, Kenneth E. Turner, Jean L. Steiner, and N. Andy Cole
Grazing cattle are mobile point sources of methane (CH4) and present challenges to quantify emissions using noninterfering micrometeorological methods (MM). Stocking density is low and cattle can bunch up or disperse over a wide area, so knowing cattle locations is critical. The CH4 concentration downwind of a herd may only increase slightly above upwind concentration, so that careful concentration measurements are needed. The objective during the intensive field campaign of summer 2014 was to use a MM to quantify pasture-scale CH4 emissions from grazing cattle and compare results to two other methods. Study pasture was a 26.4-ha tallgrass prairie at El Reno, Oklahoma grazed by 50 cow-calf pairs (CCP). Each beef cow was fitted with a satellite tracking unit. Three open path CH4 lasers on motorized positioners scanned 16 paths that crisscrossed the pasture. Sonic anemometers measured wind speed and direction and variances of wind components. We used dispersion analysis to model CH4 dispersion from the cattle. After quality control filtering, retention of quarter-hour emission data was 24% during five days. Best quality data were acquired when cows were least active. Most per capita emission rates (PCER) ranged from 100 to 600 g CH4 d-1 CCP-1. Mean PCER for five days during the campaign was 359±61 g CH4 d-1 CCP-1, which included a negligible soil source/sink. Independent, concurrent measurements from two GreenFeed systems and an Intergovernmental Panel on Climate Change Tier 2 estimate of enteric CH4 emission were 385±57 and 340±57 g CH4 d-1 CCP-1, respectively. Methane emission of the CCP as a fraction of body weight (BW) for the three methods ranged from 0.49 to 0.56 g CH4 d-1 kg-1 BW. The enteric CH4 emission factor for a cow with calf grazing early season tallgrass prairie was 306±72 g d-1 AU-1 (animal unit).
Greenhouse gas emissions from beef-cattle grazing systems on temperate grasslands
Johanie Rivera-Zayas, Miguel Arango, Noortje Notenbaert, Charles W. Rice
The agricultural sector contributes about 10% of total greenhouse gas (GHG) emissions in the United States. During the last 15 yrs methane (CH4) and nitrous oxide (N2O) emissions from agricultural activities have increased by 12% and 6%, respectively. At a global scale, cattle production is responsible for 65% of GHG emissions. During 2014 cattle management was the largest emitters of CH4 representing a 23.2% of the total CH4 from anthropogenic activities. Gas samples were gathered from three grazing areas under three different burning regimes at the temperate grassland Konza Prairie Biological Station (KPBS). Burning regimes included one site in annually burned, and patch burning with two sites burned every three years on offset years. Data gathered at KPBS since 2014 implies CH4 and N2O are consumed on grazed grassland; with an increase in consumption with patch burning. Burning regimes had no effect in N2O emissions. Annual burning lowered CO2 emissions relative to patch burned. There was a significant difference with the interaction of emissions and season. Maximum CO2 and CH4 fluxes coincided with high biomass during summer and fall. Weather and edaphological conditions during fall and winter increase N2O emissions. A decrease in CO2 and CH4 fluxes, and N2O and CH4 soil uptake occurred during winter. These results quantify the role of temperate grasslands as a sink of CH4 and N2O and to understand best practices for beef cattle management.
Comparison of Tillage Treatments on Greenhouse Gas Fluxes in Established Winter Wheat Production.
Brekke L. Peterson and Jean L. Steiner
Tillage is commonly used to control weeds and prepare fields for planting. Repeated tillage can result in soil drying, sudden bursts carbon and nitrogen mineralized from soil organic matter, and alterations in soil microbial communities. The effects of tillage on winter wheat cropping systems and parameters listed above is not well understood in the Southern Plains. This study was conducted in July, 2015 at the USDA-ARS Grazinglands Research Laboratory, El Reno, Oklahoma on winter wheat sites where chisel plow, vertical tillage tool and no-till were compared. The main objective was to determine the impact of chisel plow and vertical tillage tool use on soil cycling of carbon and nitrogen cycling and greenhouse gas (GHG) flux in winter wheat production. Soil and GHG samples were measured using stationary chamber methods, over 196 hours post plowing. Results indicate that carbon dioxide and nitrous oxide emissions are greatest from chisel plow use, followed by vertical tillage tool. A pulse of soil labile carbon and nitrogen can be seen as early as 3 hours post tillage in both chisel and vertical tillage tool treatments. Both treatments had greater GHG flux compared to the no-till control. Knowledge of how different tillage practices alter soil priming and GHG emissions will help to establish sustainable management practices and improve ecosystem services, while reducing input cost.
Effect of corn-based supplementation on gas emissions, performance, and energetic losses of steers grazing wheat pasture,,
P. J. Ebert, J. S. Jennings, A. L. Shreck, N. A. Cole, and E. A. Bailey
Providing an energy supplement to cattle grazing high-quality wheat pasture can increase daily gain by 0.1 to 0.5 kg/d; however, the effects on greenhouse gas emissions is not known. Therefore we used 13 Angus-cross steers (initial body weight = 436 + 24 kg) in a crossover design to evaluate the effects of corn supplementation on gas emissions, and energy losses of steers grazing wheat pasture. Steers were allowed ad libitum access to wheat pasture (1.2 steers/ha), and were individually supplemented with one of two treatments for two, 30-day periods. Treatments were either 0.2 kg of pelleted wheat middlings (CON), or 0.2 kg of wheat middlings plus a corn supplement fed at 0.5% of body weight (SUPP). Fecal output was determined with titanium dioxide as an external marker. Methane and carbon dioxide fluxes were measured using a GreenFeed (C-Lock Inc., Rapid City, SD). Forage intake, as percent of BW, did not differ (P = 0.15) between CON (3.22%) and SUPP (3.61%). There were no differences (P > 0.47) between treatments for digestibility of organic matter or fiber. Carbon dioxide emitted tended to be less (P = 0.08) for CON (9.8 kg/d) than SUPP (10.5 kg/d). No differences (P = 0.43) were observed in methane emissions between CON and the SUPP supplement (334 and 351 g/d, respectively). However, corn supplementation decreased (P = 0.02) methane/kg of dry matter intake and methane as percent of energy intake by 20.5% and 21.6%, respectively. Under the conditions of this experiment, cereal grain supplementation decreased methane emissions per unit of feed intake by cattle grazing wheat pasture.
Effects of supplementation to steers consuming green chopped wheat forage on energy losses and nitrogen balance
A.L. Shreck, P.J. Ebert, E.A. Bailey, J.S. Jennings, K.D. Casey, B.E. Meyer, and N.A. Cole
Providing an energy supplement to cattle grazing on high-quality wheat pasture can increase average daily gain by 0.1 to 0.5 kg/day; however, its effects on greenhouse gas emissions are not known. Therefore we used 8 cross-bred steers (initial weight: 206 ± 10.7 kg) in a respiration calorimetry study to evaluate the effects of energy supplementation on energy losses and nutrient digestibility of steers fed wheat forage. The study was a 2 x 2 factorial arrangement of treatments with dietary factors consisting of either green-chop wheat forage with no supplementation (CON) or with a corn-based energy supplement fed at 0.5% of body weight daily (SUP) and intake levels of 1-times (1x) or 1.5-times (1.5x) maintenance energy requirements. Wheat forage was harvested daily and fed as green-chop to steers continuously during the 56 day study. Supplementation did not affect digestibility of organic matter, gross energy, or fiber, or heat production. The CON steers had greater (P = 0.01) oxygen consumption and tended to have (P = 0.06) greater enteric methane production than SUP steers. Carbon dioxide production was similar for CON and SUP steers. Methane production, as a proportion of gross energy intake, was 6.87% and 6.07%, for CON and SUP, respectively (P = 0.27). No difference (P = 0.39) in retained energy as a proportion of gross energy intake was noted (18.14% vs. 21.26%) between treatments. Based on this and other performance studies, energy supplementation to steers fed green-chopped wheat forage may decrease methane and carbon dioxide emissions per unit of weight gain.
Influence of protein supplementation on enteric methane production of cattle fed low-quality grass hay
A.L. Shreck, E.A. Bailey, J.S. Jennings, and N.A. Cole
Typically in the Southern Great Plains the quality of native range is lowest in the winter; therefore, cattle are frequently supplemented with protein to increase digestible forage intake and weight gain. The effects of supplementation strategies on enteric methane and carbon dioxide production are not known. Twenty-three cross-bred steer calves were individually given ad libitum access to a chopped grass hay (3.9% crude protein: CP) in Calan head gates over three 28-day periods. The calves were supplemented with: 1) no protein supplement (control CON), 2) cottonseed meal (CSM: 40% CP, 3% fat) at 0.29% of body weight daily or 3) dried distillers grains (DDG: 30% CP, 10% fat) at 0.41% of body weight daily. Treatments were rotated among steers so that each steer was on each treatment during one period of the study. Methane and carbon dioxide production were measured using a GreenFeed system (C-Lock, Inc, Rapid City, SD). Grass hay intake was greater (P < 0.01) in steers fed protein supplement (3.7, 5.8, and 5.5 kg/head (+ 0.35) daily for CON, CSM, and DDG, respectively). This led to greater (P < 0.01) total daily carbon dioxide (4.89, 5.52 and 5.45 kg/day, respectively) and methane 173, 211, and 196 g/day respectively) emissions. However, methane emissions as a % of gross energy intake were lower (P < 0.01) in supplemented steers (10.9, 8.8, and 7.9%, respectively), leading to greater energy balance for CSM (0.58 Mcal/d) and DDGS (2.38 Mcal/d) than for CON (-2.54 Mcal/d). Results indicate that the routine procedure of providing a protein supplement to cattle on poor quality pastures may decrease methane emissions per unit of dry matter intake and probably per unit of weight gain.
Intensified cow/calf production in the Southern Great Plains
Adam McGee, Jarrod Cole, Corbit Baylif, Miles Redden, Courtney Spencer, Jason Warren, Damona Doye, Ryan Reuter, Gerald Horn, and David Lalman
As competition from alternative uses for grazing land increases, enhancing productivity per acre is important to maintain and increase beef production. This multi-year study evaluates whether restricted grazing of small grains and summer annuals (INT) can reduce total land required for cow-calf production compared with an extensive production system using only native range (EXT). Cows in the EXT treatment had continuous access to native range stocked at 13.3 acres/cow-calf pair/year. Cows in the INT treatment grazed annual forages during strategic periods to reduce total land usage to 8.8 acres/cow-calf pair/year. During the winter (Dec-Mar), INT had access to wheat pasture for an average of 8 hours per week, continuous access for graze out (Mar-May), then had continuous access to native range during early summer (May-Jul) and fall (Aug-Dec); and 4 hours restricted grazing per day on summer annuals during Late Summer (Jul-Aug). The INT cow BW and body conditions score (BCS) were greater at all time points (P < 0.01) except late summer in year one (P > 0.06). During year two, BW and BCS were not different for all grazing periods (P > 0.06) except winter BCS (P = 0.02). The INT calf ADG was greater throughout year one (P < 0.05) and not different in year two (P > 0.08) between groups. Utilizing partial confinement during strategic periods of the year calf gains were increased and total land area for beef production was decreased.
Stocker cattle performance is greater when grazing patch-burned rather than unburned Cross Timbers rangeland
Corey A. Moffet and R. Ryan Reuter
Land treatments such as prescribed burning alter forage quality in a pasture. Typically, recently-burned areas have greater crude protein and total digestible nutrients than unburned areas. Improved forage quality may reduce enteric methane emissions, improve animal performance, and increase beef production per hectare, but for life-cycle analysis these effects need to be quantified. The objective of this study was to quantify the effect of a 3-yr patch-burn rotation on cattle performance and gain per hectare in the Cross Timbers ecoregion. In 2011, a study was begun on 6 pastures (192 to 309 ha) with similar ecological site composition, typical of the Cross Timbers ecoregion in south-central Oklahoma. Three pastures received the patch-burn treatment, where approximately 1/3 of the pasture is burned in late winter each year on a 3-yr rotation (burned areas are not fenced separately). The other 3 pastures were not burned. Beginning in April each year, steers (approximately 250 kg) grazed for 3 months. Stocking was targeted to remove 40% of expected annual forage production from the grazeable area (approximately 2/3 of the total area). Steers were weighed individually on and off pastures following a 16-h drylot shrink. Over a 5-year period from 2011 through 2015, steers grazing unburned pasture gained 0.35 kg/d while steers grazing patch-burned pasture gained 0.45 kg/d. These average daily gains translate into gains per hectare (grazeable area) of 14.4 kg/ha for the unburned pastures and 18.5 kg/ha for the patch-burned pastures. Beef cattle performance and beef production were increased by nearly 30% with patch-burning compared to not burning in this 5 year study.
Cattle Performance on Patch-Burned Vs. Yearly-Burned Native Tallgrass
Jaymelynn Farney, Doug Shoup, and Walt Fick
Prescribed burning of native pasture is a management practice that has been implemented in tallgrass native ranges in the Southern Great Plains for control of undesirable brush/weeds, parasites for cattle, and to improve cattle gains. Evaluation of stocker cattle performance in a patch-burning management system versus an annually burned pasture was the objective of this project. The study was conducted at the Bressner Research Center near Yates Center, Kansas from 2006-2012. Over the seven years a total of 1497 stocker steers (average initial weight 255.9 ± 1.73 kgs) were placed on 8 paddocks in April and removed in July (common ¾ season stocking rates for the area). Four pastures each were burned yearly (CON) or patch-burned (PB) where 1/3rd of each pasture was burned in a rotating schedule every three years. Individual weights were recorded at the beginning and end of grazing. Average daily gain (ADG) was determined for all animals within treatment and by year. Overall ADG was not different (P = 0.42) between CON and PB treatments. Differences were observed in ADG by year (P < 0.001) and an interaction effect (P < 0.01); however the only difference observed was a tendency (P = 0.09) for the cattle on the PB treatment in the 7th year to have a higher ADG. Patch-burning does not result in different average daily gains of stocker cattle, however in severe drought years PB might be a valuable management option for cattle performance. Yearly variability can be observed in cattle gains, primarily explained by differences in weather and pasture growing conditions.