2013 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.
This is the first report of progress in project 6218-21610-001-00D, which started in December 2012 and replaced projects 6218-12210-003-00D and 6218-21410-003-00D. Some planting was undertaken in fall of 2012, to enable some crop establishment and production during the first cropping season of the new project. Two eddy flux towers were installed on native range and on improved pasture in preparation for measurement of carbon dioxide and methane emissions from grazing livestock beginning in fall of 2013. Sites and experimental units for redcedar studies have been identified in preparation for application of experimental treatments, beginning in FY14. Greenhouse studies of variability in response to applied nitrogen in annual ryegrass were started in early spring 2013 and continued to the end of the cool season. Seed multiplication has been undertaken for big leaf vetch that is designated, with other legume species, for evaluation in field experiments scheduled to begin in late FY13 or early FY14. Seed increase of bushy-type long-duration pigeon pea is also in progress (off-site). An experiment was initiated to study warm-season annual legumes as a source of N for winter wheat under till and no-till systems, and a study of cool-season annual legumes as a source of N to forage sorghum is in progress. Widespread industry interest in canola as a break crop in continuous wheat systems prompted investigation of the possibility of using canola as an alternative cool-season forage crop. Preliminary studies have shown acceptable livestock performance (mean daily gains of 0.7 kg for heifers during 49 days of grazing). The impact of grazing on subsequent canola grain yield could not be measured, however, due to severe storm damage shortly before the planned harvest. Time-series data for annual ryegrass production were collated during the previous project, and corresponding short-period (5- or 7-day means) climatic data are being generated, prior to analysis to evaluate possible climate x productivity linkages. Two tall fescue synthetics (Syn1, Syn1RR) generated by the inducer line technology were submitted to OTT for licensing. First year PVP data was obtained on each synthetic and a check in June 2013. Seed obtained from tall fescue F1 hybrids exhibiting greater tolerance to stress, drought, and other agronomic factors were harvested in June and July 2013. Seed will be germinated in the fall of 2013 to determine type and frequency of tall fescue dihaploid generation. First cycle selections were performed on smooth bromegrass and orchardgrass populations, and seed increase is underway. A South American bromegrass (Bromus auleticus) was identified and confirmed to have resistance to 41% glyphosate herbicide applications in the spring and fall. Seed from the material was harvested for future line increase. The identification of a glyphosate-tolerant bromegrass was reported to OTT and ONP for input on the future licensing and marketability of a herbicide-tolerant grass forage product. Seed increase was made for a drought- and stress-tolerant "perfect flower" Texas bluegrass selection.