Location: Forage and Livestock Production Research2018 Annual Report
1a. Objectives (from AD-416):
The long-term objectives of this project are to develop improved techniques that will enhance ecological function and efficiency of resource use in prairie and pastureland, increase forage productivity, and promote sustainability of livestock production systems in the Southern Great Plains. Specifically, during the next five years we will focus on the following: Objective 1: Enhance productivity and ecological function of native tall-grass prairies by development of management practices, including management-intensive grazing, and restoration strategies to follow invasive brush and tree species removal. Sub-objective 1A: Compare the effects of different systems of intensive grazing on plant communities and soil properties of over-utilized tallgrass ecological sites, and define shifts in responses to applied management regimes. Sub-objective 1B: Determine greenhouse gas emissions from soil, plant, and animal components of diverse grazing systems. Sub-objective 1C: Define the influence of eastern redcedar trees on local soil conditions of abandoned cropland (old fields), and identify restoration practices that enhance conversion of retrogressed old fields to native prairie. Objective 2: Increase sustainability in grazing systems and improve year-round availability of forages for grazing through: improved pasture establishment and persistence, use of multipurpose legume crops, reduced need for purchased inputs in crop and forage production systems, and increased efficiency of water and nitrogen use. Sub-objective 2A: Assess effect of tissue damage on grass growth, development, and persistence characteristics. Sub-objective 2B: Identify forage species and management practices, including use of legume crops for green manure, that promote efficiency of resource use, especially N and water use, to increase year-round availability of forage for grazing. Objective 3: Increase marketing options, including providing high-quality farm-finished beef, through development of management systems that optimize on-farm feed resources and minimize the need for external inputs. Sub-objective 3A: Identify and evaluate forage resources for efficacy at critical times in the production cycle for farm-finished beef of different genetic types. Objective 4: Provide decision-support tools to aid land managers in evaluating climatic risks and ecologic and economic outcomes in selecting production and conservation practices and strategies for grazingland ecosystems. Objective 5: Develop improved cool-season grasses and legumes to improve productivity and sustainability of grazing and crop lands in the Southern Great Plains. Sub-objective 5A: Develop tools to support selection of improved cultivars. Sub-objective 5B: Identify germplasm of perennial cool-season grass forages adapted to heat, drought, and nutrient stresses of the Southern Great Plains.
1b. Approach (from AD-416):
Livestock production systems in the Southern Great Plains are confronted with problems of limited and uncertain forage supply, increased climatic variability, and environmental degradation that threaten economic viability and system sustainability. This project will develop management practices and identify forage genotypes that are resilient under variable climate and will increase forage productivity and input use-efficiency on livestock farms at a range of scales. Commensurate with the scope of the location as a Long-Term Agroecosystem Research network site, we will initiate assessments of greenhouse gas (GHG) emissions and agricultural production under different livestock systems of the Southern Great Plains, including both native prairie and wheat pasture. Data from this study will be pooled with results from similar flux studies in the region to evaluate climate and environmental impacts on system response. To evaluate system resilience, over-utilized prairie ecological sites with a mix of native and introduced species indicative of good and poor condition mixed grass prairie will be used to evaluate the use of infrequent, high-intensity grazing on succession and diversity of forage species at the sites. The impact of prior encroachment of redcedar on old-field nutrient and seedbank reserves and consequent recovery of understory and grass species following removal of redcedar will be assessed. The use of legumes and grasses as green manure sources will be researched for summer (sorghum) and winter (wheat) grain crops to promote efficiency of N and water use. Nitrogen turnover and utilization by the subsequent crop will be assessed. Also, N-uptake and efficiency of utilization of cool-season annual and perennial species will be measured in greenhouse experiments to develop screening methods for plant germplasm. Improved management methods will be developed to fully utilize the genetic potential of new cultivars by enhancing establishment, yields, and utilization by livestock. To increase marketing options of livestock producers, we will determine appropriate forage resources for production of farm-finished beef, either on all forage or with limited grain inputs. Interactions of animal genetic type (frame score) and finishing system (forage or grain) will be assessed. Time-series data from ryegrass trials in four southern states in the last decade will serve as the basis for examining the possible importance of 5-day and 7-day summary weather statistics of the near-surface environment, and the variations of those statistics around decade-long averages, as a predictor for seasonal production. Plant breeding technologies will be used to develop improved cultivars of perennial C3 grasses, particularly fescue, that are more persistent under the regional climatic conditions, and are more water-use efficient. Basic molecular biology and biochemistry/physiology information will be developed that will improve plant breeding techniques and products.
3. Progress Report:
This report documents progress for parent Project Number 3070-21610-002-00D, which started in December 2017 and continues research from Project Number 3070-21610-001-00D, entitled “Integrated Forage Systems for Food and Energy Production in the Southern Great Plains. Accomplishments and outreach activities are reported earlier in the 3070-21610-001-00D project. A series of pilot studies were undertaken to help develop new experiments for the succeeding project plan. Staffing levels of research scientists through the reporting period was 3.75 SY, or 62%, of the staffing level required to execute continuation of the project plan. In consequence, progress in most components during the project was hindered. In those areas where staffing and resources were adequate, implementation of the project proceeded as limited available resources allowed. ARS researchers at the Grazinglands Research Laboratory, in El Reno, Oklahoma and university collaborators began investigating the capacity of a range of underutilized grain crops from India, the Middle East, Africa, Central and South America for their capacity to grow in the southern Great Plains. To date, this research has generated an in-depth review of scientific literature related to underutilized grain-type cereal and legumes, and initial field trials of potential forage candidates, resulting in two papers on underutilized legumes; one published and one in press. ARS researchers and university collaborators also reported on studies that defined how different fertilizer (amount and type) and management (tillage systems) combinations of continuous winter wheat-summer cover crop rotations affected soil microbial communities. They found tillage systems (no-till and conventional tillage) that used best management practices had little effect on microbial communities, while type and amount of N supply had great importance. These results will help producers determine the potential value of including cover crops in cropping rotations, to improve the soil biological properties of continuous wheat agroecosystems. A study was also initiated that established eddy covariance towers in a series of paired wheat pastures to help identify potential effects of combinations of tillage systems and management for grazing of grain production. Researchers reported large variations in amounts of carbon dioxide (CO2) released among pairs of paddocks managed for grazing or grain, and that differences in plant attributes related to paddock management must be accounted for to explain effects of tillage and pasture management on CO2 flux between the atmosphere, plants, animals and soil.
Baath, G.S., Northup, B.K., Gowda, P., Turner, K.E., Rocateli, A.S. 2018. Mothbean: A potential summer crop for the Southern Great Plains. American Journal of Plant Sciences. 9(7):1391-1402. https://doi.org/10.4236/ajps.2018.97101.
Wagle, P., Gowda, P., Northup, B.K., Turner, K.E., Neel, J.P., Manjunatha, P., Zhou, Y. 2018. Variability in carbon dioxide fluxes among six winter wheat paddocks managed under different tillage and grazing practices. Atmospheric Environment. 185:100-108. https://doi.org/10.1016/j.atmosenv.2018.05.003.