Location: Soil and Water Management Research2013 Annual Report
1a. Objectives (from AD-416):
1. Develop irrigation and drainage strategies for emerging cropping systems in the North Central United States to protect water and soil resources. a. Develop methods to facilitate the success of living mulch systems through the use of supplemental irrigation, and evaluate their environmental impact. b. Develop N management strategies for large dairy operations to reduce nutrient losses through artificial subsurface drainage. 2. Reduce the potential adverse impacts of agronomic and horticultural practices on water quality: a) Identify and test innovative management practices; b) Determine factors that control the fate and transport of agrochemicals and contaminants of emerging concern. a. Identify and differentiate contaminants in surface water systems associated with the agriculture-urban interface in order to delineate contaminant sources and develop mitigation strategies. b. Compare water use requirements and characterize persistence, transport and loss pathways of contaminants with runoff from traditional and low-input turf managed with conventional or innovative practices. c. Develop management strategies to reduce nitrate-N leaching losses using fall-applied anhydrous ammonia. d. Determine factors controlling the fate and transport of agrochemicals and contaminants of emerging concern.
1b. Approach (from AD-416):
Development of agricultural management strategies and basic research on fate and behavior of agrochemicals are integral parts of both objectives. Research will be designed to maximize the information that can be used to attain multiple objectives. For instance, the research in Objective 1a and 1b will include development of irrigation and drainage strategies for emerging cropping systems that will require less N and reduce losses of nitrate-N to water bodies from agrochemicals, while Objective 2a will identify production management systems that minimize offsite transport of agrochemicals to surface water. Objective 2b will determine factors that control the fate and transport of agrochemicals and contaminants of emerging concern in the cropping systems with the irrigation and drainage strategies identified in Objective 1a and 1b, and in the production management systems identified in Objective 2a. The complementarity in fundamental processes studied, sample and data collection methods, and analytical methods across objectives will facilitate integration of results and provide important operational efficiencies. A cohesive, multidisciplinary team is needed to accomplish the presented range of research objectives.
3. Progress Report:
Objective 1a: Field plots were established in an irrigated field at the Rosemount Research and Outreach Center. Suction cup samplers were installed in all plots, as were soil moisture and temperature sensors. A fertigation system was also installed. A hydraulic device was obtained from DuPont for removing large intact cores to be used as lysimeters, and it was tested onsite. Lysimeters will be installed in fall 2013. 1b: We completed monitoring drainage flow and water quality for a three-year comparison of dairy slurry application methods – injection versus center pivot irrigation – in a large-field scale (65 ha) experiment. One field has been converted to alfalfa. Changes to water sampling and analysis methods have been initiated per the finalized research project protocols. 2a: We instrumented four sub-watersheds, collected water and sediment samples, and extracted samples by solid phase or accelerated solvent extraction. Currently we are analyzing the extracts for veterinary pharmaceuticals, hormones, and pesticides using liquid chromatography tandem-mass spectrometry. Our results will provide tools to identify sources of surface water contaminants, providing insight for targeting mitigation approaches. 2b: Research was initiated on amending soils with activated charcoal or biochar to reduce off-site transport of aminocyclopyrachlor, a herbicide with high potential mobility in some soils. Studies on aminocyclopyrachlor adsorption to biochar and biochar-amended soils have been completed. Turf plots were seeded with traditional creeping bentgrass or low-input fine fescue. Runoff gutters, trapezoidal flumes, rain gages, flow meters and automated samplers were installed. The turf is being maintained as a golf course fairway. Fertilizer and an insecticide have been applied and runoff, resulting from a natural rain event, has been collected. Additional applications of fertilizer and pesticides, collection of runoff, analysis of runoff and evaluation of turf health will be performed to determine which turf system is most effective at reducing the off-site transport of contaminants with runoff. 2c: Lab incubation experiments examining effects of biochar on soil nitrification have been partially completed and are continuing. Some of these experiments were conducted using soils from New Zealand as part of an international research exchange program. Plot-scale field experiments have been established utilizing newly developed techniques and equipment for injecting nitrapyrin in the spring in the same location within each corn row where anhydrous ammonia was applied the previous fall. The effects of spring nitrapyrin application on soil nitrate and grain yield are being measured; 2d: Laboratory incubations are also being continued on the impact of strobilurin fungicides on soybean residue mineralization as well as the impact of tillage management on soil quality and microbial corn stover mineralization. Laboratory sorption experiments are being conducted on a recently registered herbicide, indaziflam, and three major metabolites to characterize potential movement in soil.
1. Developed and demonstrated a method for field-scale vegetative propagation of kura clover. Kura clover is a potentially valuable tool for reducing erosion and nitrogen fertilizer use because it is a rhizomatous perennial legume, which means it can serve as a living mulch and N source for corn and other row crops. However, its use has been limited, in part because it is difficult to establish from seed. We showed that it can be readily established vegetatively, by harvesting crowns from an existing field with a potato digger, then spreading them into a newly plowed field, disking them in, and packing them with a roller. This practice will reduce erosion and nitrogen fertilizer use.
2. Management practices to reduce offsite transport of oxyfluofen in olive crops. To reduce potential offsite transport of the herbicide oxyfluofen in olive crops, the influence of soil components and olive-oil mill waste (OOMW) amendment on the fate of oxyfluorfen in two olive cropped soils was determined. Soil adsorption, which is affected mainly by soil clay and organic components, and amendment with OOMW, was the most important process related to oxyflurofen dissipation. Persistence was directly related to sorption and the half-lives increased upon OOMW amendment. Leaching through the soil profile depended on soil composition, temperature and soil porosity. At low temperature, oxyfluorfen accumulated in the top 5 cm of soils, and this behavior was enhanced by OOMW-amendment. In contrast, at higher temperatures oxyfluorfen moved through the soil profile, as a result of association with DOM soil particles. Based on these results, farmers should use oxyfluorfen with caution in Winter because of the high risk of runoff losses; in Spring, it should be used with caution in soils with high OM content. OOMW soil amendment is not a recommended practice when using oxyfluorfen. Following these general rules, potential off site transport of oxyfluorfen will be reduced.
3. Greenhouse gas production in soil with composted and non-composted biochars. Biomass feed stocks can be used to generate a more stable carbon form (biochar) that is returned to the soil sequestering atmospheric carbon into a slower cycling pool, resulting in alterations in plant growth/yield and microbial soil processes. However, the mechanisms behind the “biochar effect” have not been fully elucidated. In the present work, ARS scientists at St. Paul, MN have examined the impacts of pre-composting the biochar prior to soil application, specifically in regards to the sorbed volatile organic compound fingerprints and the results impact on greenhouse gas emissions. These findings could provide additional insight and direction in the focus of the benefits of biochar additions on plant and soil microbial communities. These results are significant to farmers and policy makers and will assist scientists and engineers in developing improved biochars based on properties to minimize greenhouse gas implications and improve soil carbon management.
4. Nitrogen and phosphorus transport in runoff from fairway turf. Enrichment of surface waters with excess nutrients is associated with increased algal blooms, euthrophication and hypoxic zones, as reported in the northern Gulf of Mexico. A source of nutrients to surface waters results from fertilizer runoff. Management strategies used to maintain turf on golf courses and recreational fields often includes aerification and application of fertilizer. Although research exists on benefits of core cultivation and verticutting (VC) to reduce thatch and the transport of applied chemicals with runoff, there are no studies reporting the effect of coupling these management practices with the goal of further reduction of off-site transport of fertilizer with runoff. Research conducted by ARS scientists in St. Paul, MN showed no reduction or enhancement of risk associated with surface water concentrations of phosphorus or nitrogen, resulting from runoff from creeping bentgrass turf that was managed with HTCC+VC compared to HTCC. Data obtained in this research will be useful to grounds superintendents when selecting best management practices and to scientists seeking data relating runoff to land management for watershed-scale modeling.
Suddaby, L.A., Beulke, S., van Beinum, W., Celis, R., Koskinen, W.C., Brown, C.D. 2013. Re-analysis of experiments to quantify irreversibility of pesticide sorption-desorption in soil. Journal of Agricultural and Food Chemistry. 61(9):2033-2038.