Location: Forage and Livestock Production Research2011 Annual Report
1a. Objectives (from AD-416)
The primary goal is to develop a knowledge base and guidelines that will enable producers in the southern Great Plains to diversify forage-based systems, to enhance flexibility and efficiency, and to reduce economic and environmental risks under variable climate, market and policy conditions. The approach is to develop sustainable systems that integrate a diversity of plant species including forages for livestock, multi-purpose crops, and biomass production. Specific objectives include: Objective 1: Provide perennial grasses to regional livestock producers that are adapted, productive, persistent, exhibit desired agronomic characteristics, and can be included in year-round forage based production systems. Sub-objective 1.A. Develop and evaluate germplasm resources of perennial cool-season grass forages that exhibit favorable agronomic characteristics and are adapted to the climate of the southern Great Plains. Sub-objective 1.B. Develop PCR-based molecular markers to assist perennial cool-season grass breeding, with emphasis on bluegrasses. Sub-objective 1.C. Evaluate smooth bromegrass, wheatgrasses, and tall fescues under intensive, short-duration grazing during spring and fall in near year-long forage production systems. Objective 2: Evaluate quality and anti-quality factors in existing forage based livestock production systems that limit animal performance. Sub-objective 2.A. Evaluate adapted winter wheat cultivars and breeding lines for variation in concentrations of secondary metabolites that may limit the incidence of frothy bloat, and for accumulation of nitrate that may limit performance of cattle grazing wheat forage. Sub-objective 2.B. Provide a real-time, remote-sensing based approach for estimating forage quality in the field. Objective 3: Incorporate multipurpose legume and grass forage, grain, and biomass crops into integrated and diversified systems that provide a range of agricultural opportunities. Sub-objective 3.A. Assess the feasibility of integrating multipurpose forage and grain crops into diversified forage and livestock production systems. Sub-objective 3.B. Provide the knowledge and guidelines required to integrate biomass/bioenergy crops into agricultural land management systems of the southern Great Plains. Sub-objective 3.C. Assess amounts of nitrogen contributed to subsequent forage, grain and biomass crops by annual and perennial legumes. Objective 4: Provide the knowledge and guidelines required to implement and manage year-long forage based livestock production systems. Sub-objective 4.A. Design, install, and evaluate farm-scale, year-long forage production systems that include multiple forage species to fill gaps in spring and fall when high-quality forage is not available. Sub-objective 4.B. Determine whether fast-growing annual legumes and grasses have potential as gap-filling forages for use in near year-long forage production systems in the southern Great Plains.
1b. Approach (from AD-416)
Germplasm with potential for use in the region will be obtained from a variety of sources and evaluated in the field for adaptation, productivity, forage quality, and other traits. Persistence, productivity, and quality of selected perennial cool-season grasses will be genetically improved through traditional and marker assisted breeding methods and interspecific hybridization. Forage crop sequences, including grass, legumes, and legume/grass mixtures will be evaluated in the field under varying levels of fertilization, grazing pressure, and abiotic stress. Hyperspectral reflectance data will be compared to laboratory analyses and bench top near-infrared spectroscopy as an approach to monitoring in-field forage quality and biomass production. Productive and adapted bioenergy feedstock crops will be identified and efficient feedstock production systems developed. Approaches to incorporate feedstock production into existing forage and livestock production systems will be investigated. All proposed research will be in collaboration with ARS, university and private cooperators where appropriate and mutually beneficial.
3. Progress Report
Progress was made for all objectives. To develop new germplasm that contributes to year-round grassland systems, populations of smooth bromegrass, orchardgrass, and tall fescue were entered into national forage production performance trials. Small-scale seed production plots of tall fescue, an interspecies hybrid - festlolium, and smooth bromegrass were seeded and are maintained at three locations, and tall fescue dihaploid recoveries were seeded at Mound Valley, KS, for evaluations regarding inheritance of forage quality attributes. Seed increase and genetic distance determinations were made utilizing 40 Simple Sequence Repeat (SSR) Poa markers on a series of Poa sp. and a perfect flowered Poa arachnifera (Texas bluegrass) genetic stock and other P. arachnifera x P. secunda hybrid populations. Seed increases of all will proceed in 2012. Selection within a P. arachnifera x P. secunda (perfect-flowered) population were maintained and allowed to produce cross-hybrid seed that will be harvested in July 2011 for increase in 2012. A perfect flowered Texas bluegrass population was generated, and SY seeks collaboration for seed increase and potential release. A line that stimulates dihaploid production, IL1, was released publically to the ATCC and as a genetic stock release (PI660129). Subobjective 2A is complete and the PI has retired. Subobjective 2B has been completed ahead of schedule and the work published. Additional research opportunities presented themselves, and remotely sensed data are being collected on alfalfa cultivars and clones to determine if remotely sensed data can be used for plant screening. Studies with the forage legumes guar, lablab, and soybean will be completed at the end of the wheat growing season 2012. The pigeon pea grazing study was completed and reported. A pigeon pea hybrid study was terminated because the maturity was long, and the varieties did not flower under SGP environmental conditions. Seed from an early maturing pigeon pea was obtained from ICRISAT for evaluation. Seeds of drought resistant, early maturing cow peas developed in Nigeria were obtained from Texas A&M Univ. for evaluation in SGP. Studies on high intensity grazing tall wheatgrass with stocker cattle for 35 to 40 days before and after wheat pasture (October and May) will continue. However, severe drought during FY 2011 caused complete stand failure of paddocks of experimental cultivars of non-toxic endophyte-infected, and non-infected tall fescues that were part of the experiment. Various combinations of forage types including annuals and perennials, cool- and warm-season grasses, and legumes continue to be used to extend grazing season with the ultimate goal of forage-finished beef, and show promise to that goal. This year has provided acute notice of the risks involved in these intensive systems as a drought severely limited grazing during the winter and has curtailed most plant growth during the summer so that some grazing plans were not completed.
1. Grass pea is marginal as an N contributor to wheat systems. Rising costs of inorganic fertilizers has renewed interest in legumes for cropping systems in the Southern Great Plains of USA. ARS scientists at El Reno, OK, examined Grass pea, a cool-season legume, for its potential to supply nitrogen for the subsequent wheat crop under both conventional and no-till. Grass pea grown as a cover crop supplied a significant but small amount of N to subsequent wheat crops because high temperatures and limited soil water resulted in low biomass production and low N fixation of the Grass pea during the short summer growth period between wheat harvest and wheat planting. We concluded that Grass pea was only marginally effective as a pre-plant source of nitrogen for wheat under both continuous no-till and conventional tillage, primarily due to high temperatures in the late summer and limited availability of soil moisture.
2. High spatial resolution satellite data can be used to measure above-ground mass of redcedar. There is a need to quantify the amount of Eastern redcedar above-ground mass over large land areas to support rangeland conservation efforts and to support commercial and Federal biofuel initiatives. However, large-area measurements of above-ground mass are only feasible using remote sensing methods. ARS scientists at El Reno, OK, demonstrated that QuickBird high spatial resolution satellite imagery can be used to measure above-ground mass. From the study, an equation relating canopy surface area to above-ground dry mass was produced and successfully tested on an independent study site. The equation was then used to estimate above-ground mass for 17 counties in Oklahoma. The equation is being used by personnel from the Bureau of Indian Affairs to estimate redcedar mass on selected land allotments and will be useful to other agencies and businesses trying to assess redcedar mass for commercial use.Rao, S.C., Northup, B.K. 2011. Grass pea (Lathyrus Sativus L.) as a pre-plant N source for continuous conventionally tilled winter wheat. Crop Science. 51:1-9.