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Goals: The first long-term goal of the proposed study is a multi-disciplinary investigation into the use of biosolids as a fertilizer in a sustainable agroecosystem management setting. <P>The supporting objectives (OBJ) of this goal are to quantify the impact of biosolid fertilization on: OBJ 1: Beef production and overall economic viability, OBJ 2: Meat quality and safety, and OBJ 3: The natural ecosystem.<P> The second long-term goal of the proposed study is fundamental research evaluating the use of biomarkers in sustainable agroecosystem management research. The supporting objective of this second goal is to evaluate if stable isotope biomarkers, which are commonly used in natural systems, can be effectively used to understand the agricultural food chain and linkages between the managed agricultural system and a native ecosystem. <P>Target dates: Fertilization of experimental field plots: Spring 08/09 Soil sampling: - before sludge application: Spring 08/09 - before seeding: Spring 08/09 - before haying: Summer 08/09 Plant sampling: - young: Summer 08/09 - medium: Summer 08/09 - mature: Summer 08/09 Insect sampling: Spring/Summer 08/09 Haying: Fall 08/09 Cattle feeding period: Summer to Fall 08/09 Body weight, condition score: Bi-weekly Summer to Fall 08/09 Ultra-sound: Fall 08/09 Slaughter of animals, Meat sampling: Winter 2010.<P> Expected outputs: We expect that the results of the present proposal will allow for making recommendations for accommodating the use of biosolids as an alternative to the use of commercial fertilizer which will result in the long-range improvement of sustainable US agriculture and food systems. The research proposed in this project will serve as a foundation for more detailed research on the sustainable use of biosolids in agriculture. The results of the present proposal will show if the current experimental set-up needs to be optimized by including more animals per treatment.<P> If the results of the study indicate that biosolid fertilization will influence animal production, product quality and safety, and the natural ecosystem in a negative way, a follow up study will include different treatments of biosolids before application as a fertilizer. The approach developed in this proposal with regard to the natural ecosystem will be developed in future work to more generally address the interconnectivity between managed and natural ecosystems (and will be extended to other taxa, including birds and mammals). The proximity of cultivated fields to native habitat may have a negative impact on surrounding ecosystems if, for example, predatory species (insects or vertebrates) associated with fertilized crops move into native habitats and prey on native species. <P>On the other hand, many native birds and mammals in the Great Basin depend on insects as food. For example, sage grouse, an important game bird whose populations are in decline, depend on an abundance of insect prey during breeding season. If energy flows from cultivated fields into the native environment, then proximity to farms could benefit native birds and mammals, even if they don't forage directly in the fields.
Non-Technical Summary: Nutrient cycling is an important part of sustainable agricultural systems. Biosolids are the by-product of waste water treatment plants, and are normally disposed of via surface disposal routes. Recycling of nutrients in municipal biosolids to agricultural fields improves sustainable US agriculture and food systems. However, consumers may express concern about the inclusion of municipal waste in the food production process. The long-term goal of this study is a multi-disciplinary investigation into the use of biosolid fertilizer in a sustainable agroecosystem management setting. Supporting objectives of this goal are to quantify the impact of biosolid fertilization on: 1) beef production and overall economic viability, 2) meat quality and safety, and 3) the natural ecosystem. The second long-term goal of this study is fundamental research evaluating the efficacy of stable isotope biomarkers to tract nutrient flow in an agroecosystem. Fifty Angus yearling heifers will be fed for two consecutive years either on crops originating from biosolid fertilized plots or non-fertilized plots. Animal production (growth and body condition) will be included in a calculation of overall economic viability for the management system. Meat quality (marbling, tenderness, sensory characteristics) will be compared between the treatments as well as product safety (amount of heavy metals in the meat product). Carbon and nitrogen stable isotopes will be used to evaluate the traceability of biosolid fertilizer into plant crops and meat products, and to evaluate if energy derived from crops that are fertilized with biosolids is traveling into the native habitat via the movement of insects from cultivated fields into adjacent rangelands. This proposal develops an interdisciplinary approach to monitoring an agroecosystem system by quantifying product quality and safety and monitoring ecosystem changes resulting from the implementation of this system. <P> Approach: We will measure stable isotopes (carbon and nitrogen) in soil, forage, and cattle across treatments and into the native habitat. We will utilize a duel source mixing model for 13C and 15N to determine the consumers resource use derived from biosolids additions and natural background variation. The impact of the use of sewage sludge fertilization on beef production will be evaluated by comparing growth, body condition, and carcass characteristics at slaughter between cattle fed on biosolid fertilized crops and those fed on non-fertilized crops. All cattle will be weighed once weekly and body condition will be scored according to a subjective visual scoring system. In addition, ultra-sound backfat measurements will be collected. At slaughter, carcass measurements will be taken of rib eye area, back fat and kidney heart pelvic fat. A cost-benefit analysis will be calculated from available data, including the benefit of using biosolids to the producer, recycling by-products by waste-water plants, and the positive/negative effect of biosolid fertilization on beef production. We will use the biomarker method to evaluate if an isotopic signature derived from biosolids can be detected in crops and subsequently in beef products. Secondly, we will evaluate if the use of biosolids as a fertilizer has a negative impact on product quality by comparing meat quality traits of cattle fed on biosolid fertilized crops, and those that were fed on non-fertilized crops. At slaughter, in each individual, meat samples will be evaluated for marbling scores, tenderness, consumer acceptance, and chemical fatty acid analysis. Thirdly, we will evaluate if the use of biosolids as a fertilizer has a negative impact on product safety by comparing meat samples of cattle fed on biosolid fertilized crops and on non-fertilized crops that will be analyzed for the presence of metals. These values will be compared with the values derived from soil samples in order to evaluate if chemical elements in biosolids end up in the meat product. We will use the biomarker method to evaluate if energy derived from crops that are fertilized with biosolids is traveling into the native sagebrush habitat via the movement of insects from cultivated fields into adjacent wildlands. We will sample insects across habitats and look for the presence of biosolid-derived biomarkers in both habitats. We will use a two-source mixing model to determine the energetic contribution of biosolid derived nutrients versus the natural background concentrations of plant material. The model will account for sources and variability within those sources. We will sample insects in transects through the following communities: biosolid-treated grass fields, control grass fields, neighboring alfalfa fields, and sagebrush habitat. Each community type will be represented by two fields or areas, and each area will be visited every two weeks, with two transects walked per field per visit. We will focus on two trophic levels: predatory beetles, and herbivorous as well as granivorous beetles and leafhoppers. For chemical analyses, we will focus on 4 species: two predatory coccinellids and two herbivores.