1. Evaluate plant through micro-patch scale responses of new and existing lines of forage species for enhanced climate resilience and positive responses to management. • Sub-objective 1.A: Evaluate frequency and level of dihaploid production in meadow fescue, creeping fescue, and Festuloliums. • Sub-objective 1.B: Generate and evaluate a perennial Lolium inducer line with the ability to produce dihaploids. • Sub-objective 1.C: Generate and evaluate apomictic, hexaploid F1 hybrid eastern gamagrass (Tripsacum dactyloides) germplasm. 2. Define responses of patch-scale attributes at the soil-plant-animal interface to environment and management to improve nutrient-use and production efficiency in forages and animals. • Sub-objective 2.A: Define the longer-term capacity of annual cool- and warm-season legumes as sources of green nitrogen (N) for production of cool- and warm-season forages. • Sub-objective 2.B: Identify and evaluate forage resources for efficacy at critical times in the production cycle of farm-finished beef, and their relationships with frame score, calf growth rate, carcass quality, and economic returns. 3. Examine paddock-scale responses of the soil-plant-animal complex in response to applied management using multi-scale data to assess the potential of diverse ranges of forage and grain crops for function as multi-use crops. • Sub-objective 3.A: Measure responses, and model, novel warm-season annual pulses for their use in grazing and cropping agroecosystems of the SGP. • Sub-objective 3.B: Define carbon (C), N, and microbial fluxes in row crop, wheat-based, and native agroecosystems under different forms of management: green manures, fertilizer inputs, prescribed fire, and grazing. 4. Measure and model landscape-scale responses of soil-plant-animal-atmosphere complexes to identify improved and innovative management strategies that enhance ecological function of grazing lands and increase resilience of production systems. • Sub-Objective 4.A: Establish a network of integrated flux measurement systems (“GRL-FLUXNET”. • Sub-objective 4.B: Characterize the impacts of climate variability and management on different forages at local and regional scales in the SGP. • Sub-objective 4.C: Quantify dynamics of C and water (H2O) balances of native prairie, tame pastures and croplands in response to management practices and biophysical factors. • Sub-objective 4.D: Upscale paddock-level fluxes of C and H2O to regional scales using remote sensing approaches. • Sub-objective 4.E: Improve water management practices and water productivity by reducing non-productive water loss.
Limited and uncertain forage supply, increased climatic variability, and environmental degradation impact livestock and crop production systems in the Southern Great Plains (SGP) and threaten agroecosystem viability and sustainability. This project will develop management practices and identify crop and forage genotypes that are resilient under variable climate and will increase forage productivity and resource use-efficiency on mixed-agriculture farms across a range of scales. Increased forage productivity from native prairie and tame pasturelands will be achieved through use of practices that enhance ecological condition of grazing lands and minimize or reverse on-farm and downstream environmental damage. New decision-support tools will assist producers in timing and choice of management practices that maximize resource use efficiency under variable climatic conditions. Improved resource use efficiency will reduce unit cost of forage and crop production, and contribute to sustainability of forage-based livestock production. Enhancement of on-farm capacity for forage production is important because increased forage supplies can substitute for feed resources lost to competing enterprises such as grain crops and bioenergy production. Forage-based livestock production that uses improved management practices to enhance ecological function of prairie and pastureland will increase resilience of production systems, increase food security, add value to farming operations, and mitigate greenhouse gas emissions. The end-result will be improved efficiencies of beef production with less grain and fossil fuel inputs, less need for capital through increased use of on-farm products, and increased competitiveness and profitability for producers. To accomplish this goal, understanding interactions between different factors of the soil-plant-animal-atmosphere interface is required to match input resources to desired useful products and ecological benefits.
Research within each of sub-objective is proceeding to schedules in milestones. An ARS researcher at El Reno, Oklahoma, continued developing germplasms of different introduced and native grass species within Sub-Objectives 1.A, 1.B, and 1.C. Within Sub-Objective 1.A, suitable F1 (first generation) hybrids were evaluated for dihaploid generation in Oregon by cooperator. Dihaploids were retained and placed under agronomic evaluations for phenotype, maturity, fertility, and persistence. In Sub-Objective 1.B, potential perennial inducer lines were identified. A patent application for a technique that induces rhizome (underground stems that produces shoots) formation in fescue species was initiated. In Sub-Objective 1.C, 600 offspring from pentaploid eastern gamagrass x diploid eastern gamagrass individuals were generated and germinated, and the first 100 samples were examined to identify 6n (hexaploid) offspring by flow cytometry analysis. Plant materials under the three Sub-Objectives are being developed to provide agricultural producers with perennial forages capable of rapidly developing viable stands, and of being productive in drought-affected areas and under low levels of fertilization. A team of ARS researchers at El Reno, Oklahoma, in collaboration with Oklahoma State University and Kansas State University, expanded efforts within Sub-Objectives 2.A.1, and 2.A.2. ARS researchers at El Reno, Oklahoma, and collaborators at Kansas State University described 5 years of precipitation storage and use efficiencies of intensive winter wheat – summer green nitrogen (N) systems in Sub-Objective 2.A.1. Ancillary research by ARS researchers at El Reno, Oklahoma, and collaborators at Oklahoma State University reported on water use and water use efficiencies of grain and forage production by winter wheat double-cropped with soybean. Within Sub-Objective 2.A.2, ARS researchers and collaborators at Kansas State University, analyzed the first four years data on responses of forage production in response to green N treatments. Ancillary research reported on the effects of cool-season grass and legume-based organic N on nitrous oxide emissions in a system of forage production by a warm-season grass. Results identified a series of issues to be addressed in future research, to improve the transfer of N in legume biomass to following cash crops, and new experiments were initiated to test other potential forage and grain systems. Based on results from studies in Sub-Objectives 2.A.1, and 2.A.2, a team of ARS researchers, in collaboration with scientists at the Oklahoma State University and Kansas State University, expanded research in a new series of experiments to test a broader range of cool-season and warm-season crop rotations within the National Institute of Food and Agriculture Project ‘Increasing Water Productivity, Nutrient Use Efficiency, and Soil Health in Rainfed Agricultural Systems of Semi-Arid Southern Great Plains’. A team of ARS researchers at El Reno, Oklahoma, have continued and expanded studies in Sub-Objective 2.B that will aid in defining how different forage sequences affect growth by yearling cattle that are entirely, or largely, finished on pasture. Results of studies within Objective 2 will allow the development of new tools and techniques that agricultural producers in the Southern Great Plains can apply to improve forage production in response to the variable climate of the region. ARS scientists at El Reno, Oklahoma, in collaboration with researchers at Oklahoma State University, completed an experiment in Sub-Objective 3.A to model the performance of continuous forage soybean-winter wheat rotations in rainfed environments of the southern Great Plains. Other work defined the effect of a novel grain legume grown for green N on subsequent cotton crops. Ancillary studies produced a remote sensing tool to predict forage quality of a novel grain-type cereal grass – common to India and Africa – that is being tested in the southern Great Plains. ARS Researchers at El Reno, Oklahoma collected data during the fifth year of a long-term experiment in Sub-Objective 3.B that will develop databases that describe how soils and plant communities of southern tallgrass prairie respond to combinations of annual prescribed spring burns and intensive grazing at different times during the early growing season. Progress was hampered by recent restrictions related to requirements of laboratory staff receiving permission from first nations groups to apply prescribed burns, which prevented application of prescribed burns in 2021. This resulted in the loss of one years’ treatment application and collected data, and interruption of accumulated treatment effects over the previous 4 years. In response, pastures were grazed without burning, to compare carbon, energy, and water fluxes of southern tallgrass prairie between no burning and grazing (2021) and burning and grazing (2020). Results of studies within Objective 3 provide agricultural producers in the Southern Great Plains, and other regions with similar environments, with new information and tools to enhance sustainable management of croplands and native rangelands. ARS researchers met requirements of Sub-Objective 4.A by applying eddy covariance (EC) systems to 16 different types of annual and perennial pastures and croplands that were part of the Grazinglands Research Laboratory Flux Network (GRL-FLUXNET). Data from pastures of winter wheat, alfalfa, native prairie, and other perennial and annual forage and grain crops within the network are collected on a yearlong basis to develop databases that are mined to answer research questions and inform land managers. Under Sub-Objective 4.B, ARS scientists at El Reno, Oklahoma, in collaboration with university researchers, continue to integrate data collected from remotely sensed observations and EC measurements of carbon, water, and energy fluxes from pasture and cropland under different systems of management, to investigate their interactions with climate variability. Evapotranspiration products at different scales of time and space for native prairie and managed pastures were compared. A team of ARS Scientists at El Reno, Oklahoma undertook studies under Sub-Objective 4.C, to describe the dynamics that exist in the carbon and water balance of different grassland and cropland systems in response to applied management from data collected by subsets of EC systems within the “GRL-FLUXNET’ system. These efforts resulted in predictions of evapotranspiration by winter wheat using pixel-based models of energy balance, and simulated evapotranspiration and biomass production by winter wheat under contrasting tillage systems with the Agricultural Policy/Environmental eXtender (APEX) model. A series of new studies were initiated to examine pasture-scale carbon dioxide dynamics, evapotranspiration, and resource use efficiencies of a subset of crop rotations being tested in the National Institute of Food and Agriculture Project ‘Increasing Water Productivity, Nutrient Use Efficiency, and Soil Health in Rainfed Agricultural Systems of Semi-Arid Southern Great Plains’ within Sub-Objectives 2.A.1 and 2.A.2. ARS Researchers at El Reno, Oklahoma continued the collection of regional-scale data related to evapotranspiration and biomass production of native grasslands under Sub-Objective 4.D. This collected data will be used to develop regional-scale maps to help describe how climate affects grassland productivity at multi-state scales. Under Sub-Objective 4.E, ARS scientists undertook studies to provide information to improve water management in the southern Great Plains. Two journal papers reported techniques that separate the two parts of evapotranspiration (evaporation of water from soils; transpiration of water by plants through photosynthesis) for a series of grain crops. Results of studies within Objective 4 provide researchers, extension personnel, and land managers in the Southern Great Plains with information on carbon, energy, and water dynamics for a range of crop and forage systems, and low-cost tools to more accurately describe water use by crops.
1. Modelling water use in intensive, continuous forage soybean – winter wheat crop rotations. ARS researchers at El Reno, Oklahoma, in collaboration with scientists at Oklahoma State University, modelled the performance of continuous rotations of winter wheat that was double-cropped with forage soybean during the summers between wheat crops. The study used different sub-systems of the Decision Support System for Agrotechnology Transfer-Cropping System (DSSAT) Model to assess: yield and water use of forage soybeans belonging to different maturity groups; how they affected production and water use by following crops of winter wheat; and overall function of double-cropped systems compared to summer fallow-winter wheat systems. Modelling outputs provide producers in the Southern Great Plains (SGP) with information and management guidelines that will help improve the function of intensive forage soybean - winter wheat rotations and provide producers guidance on areas within the SGP where such rotations will be most effective.
2. Partitioning evaporation and transpiration for grain and forage crops from measures of evapotranspiration. ARS researchers at El Reno, Oklahoma, in collaboration with university collaborators, reported on a series of research projects that developed tools which allowed the partition of evapotranspiration into separate estimates of evaporation (water lost from the soil surface) and transpiration (water used by plants when growing) for different grain and forage crops, and perennial pastures. These tools will allow outreach and extension personnel to provide producers with more accurate definitions of how efficient different grain and forage crops are in using water and precipitation in biomass production and help identify unproductive losses of soil water that can be reduced by changes in management.
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