Recipient Organization
UNIV OF WISCONSIN
21 N PARK ST STE 6401
MADISON,WI 53715-1218
Performing Department
Biological Systems Engineering
Non Technical Summary
Tile drainage is an effective agricultural field management technique to reduce subsurface water to optimize crop growth and yield. Dairy operations in Wisconsin (WI) produce tens of millions of gallons of manure each year - part of which requires application on fields with subsurface drainage. Manure contains essential crop nutrients which can be used as fertilizer for crop production. Land application of manure is an effective way to return nutrients to agricultural land and increase overall soil health to maintain sustainable food production. However, application of manure on tile drained fields increases the transfer of nutrients, sediments and other pollutants to surface water at the discharge of the tile line. Management of tiles lines and treatment of effluent is critical to limiting the transfer of pollutants from manure applications to surface water. Research has shown that field scale management practices have not contributed to watershed scale reductions in nutrients. Treatment strategies which can further reduce nitrogen and phosphorus are needed to reduce the impact to waterways. Previously developed treatment systems require extensive land base to remove nitrogen and phosphorus making implementation not practical. In addition, the systems developed have focused on reductions in only one nutrient whereas tile drains are known to contribute excessive nitrogen and phosphorus, thereby requiring attention to both for overall environmental health. This study will evaluate the potential of an in-line treatment system to reduce nitrogen and phosphorus in laboratory and field scale implementations in order to reduce nutrient loading to waterways. A cost work-up will also be conducted on the final field scale system to determine the overall implementation costs for this type of installation as economic constraints have been a leading cause of systems not being installed or maintained in the past. This data will be used to develop a treatment design for producers with tile drainage systems and to leverage additional funding for continued research in the area (incorporating field and treatment practices and evaluation on a watershed scale).
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The overall goal of this project is to develop a novel low cost, inline tile treatment system to reduce nutrient loads from the outlet of tile drained agricultural fields in order to reduce the impact on surface water quality. Research objectives: Finalize the design of an inline low cost tile drain treatment system to reduce N and P effluent concentrations Assess treatment media efficiency in reducing N and P concentrations in a laboratory setting Collect and assess field level N and P fluxes before and after the treatment system at two sites Analyze data and develop educational materials including treatment design (this includes a spreadsheet development for designers to size systems accurately), installation, and management plans for small economical treatment systems
Project Methods
An inline treatment system has been designed to improve water quality of tile drainage systems without impacting available field area, Figure 2. The treatment system consists of linked cartridges containing media to increase denitrification and to capture TDP. The treatment system is designed to be installed within the lower portion of the main drainage line (segments nearest the outlet) using a chain and hoist that is pulled into the tile line through a riser. The treatment system is intended to treat low flows within the system as these have been shown to represent the highest N & P concentrations from tile drainage effluent data collected from Discovery Farms in WI. Therefore the treatment cartridges shown in Figure 2 will be positioned in the lower half of the tile line to provide N & P removal from low flow and to limit the restrictions on high flows, thereby not impeding the purpose of the drainage system. The treatment system will focus primarily on N & P removal using materials ideal for phosphorus sorption and on nitrate removal by denitrification. Many different media have been used to attempt to remove N & P from agricultural and urban runoff. A variety of low cost media have been shown to effect removal of N and P. For N removal sawdust is a low cost media with low retention times necessary to achieve nitrogen removal through denitrification as compared to alternative media examined. This is evidenced by Van Driel et al. (2006) who were able to remove 4.5 ± 2.5 mg/L-day NO3-N from a low concentrated wastewater with a hydraulic retention time of only 1.0 ± 0.7 days. Phosphorus removal is generally achieved through adsorption processes and can be related to iron content which binds P. Cucarella & Renman (2008) compared the phosphorus adsorption capacity for a variety of materials. Many of the media examined showed the potential for a significant amount of phosphorus removal, but Utelite was relatively low cost and did not exhibit the potential to leach other environmental contaminants (such as steel slag). Zhu (1997) found the adsorption capacity of Utelite to be 3.46 mg P g-1. For treatment of tile drainage it is critical for the treatment media to be low cost, readily available, and disposable using land application techniques. The primary media to be studied will be sawdust for N removal and Utelite, an iron coated soil, for P removal due to their low cost and past success in nutrient removal. In addition, biochar will also be added to determine additional removal capacities with this added amendment. In the event that the media cannot remove 50% of the influent N or P, additional media will be examined in the laboratory study portion. One treatment segment (or cartridge) will be constructed and fed tile drainage runoff for analysis of removal performance. Samples will be collected before and after the cartridge and analyzed for total N, ammonia-N, nitrate/nitrite, TP, & TDP to determine removal efficiency. Trials will be conducted in triplicate with a minimum of 10 data points for each. Two field-scale monitoring sites will be installed to characterize the performance of the tile drainage treatment system under typical management conditions at the participating farm. N and P concentrations will be quantified at the inlet to the treatment system and at the outlet using refrigerated samplers. The small low cost treatment system designed to fit within the pipe outlet of the tile drainage pipe discussed above will be installed at the end of year 1 for assessment of fall, winter and the following spring. This will allow researchers to assess the treatment capability of a field scale tile drainage N and P treatment system. Refrigerated samplers will collect discrete, time-based samples during natural rainfall- and/or snowmelt-induced runoff events at two field locations. Water-quantity and water-quality data will be collected to determine loading rates and nutrient removal. A rain gage will also be established within the field to monitor precipitation. The tile drainage pipe will be fitted with a mounting ring that will hold a non-submersible pressure transducer coupled with a nitrogen bubbler to measure flow depth, which can be converted to discharge by standard discharge relations. Data will be recorded at variable time intervals (smaller intervals during a storm event, 1-5 min; or 15-60 min otherwise) using a datalogger housed in a shelter at the site. Flow data will allow determination of loading and overall loading reductions from the treatment system. Sampling throughout each flow event will be controlled by a datalogger; when a specified flow is exceeded time-based samples are collected throughout the storm (14 in total) by pumping from the collection line at the tile outlet to a refrigerated ISCO 6712 avalanche sampler. Samples are then collected by researchers within a 24 hour period for transport to the laboratory for analysis. Laboratory analyses will be conducted on all 14 samples from each event to quantify the nutrient concentration throughout the hydrograph of each storm event which will then be used to calculate loading in combination with flow data. The field sites will be sampled during precipitation and snowmelt events with a minimum of 10 events over the research period. The tile drainage site will be characterized for farmstead information, land use, crop rotation, soil characteristics including hydraulic conductivity, texture, soil nutrient status, water holding capacity, manure/fertilizer management, and other planting characteristics. Water samples collected in the field will be analyzed for TN, ammonia, nitrate/nitrite, TP, TDP, total solids (TS), and total suspended solids (TSS) at the Biological Systems Engineering water/wastewater laboratory at the University of Wisconsin-Madison using USEPA approved methods on a SEAL AQ2 Discrete Analyzer for nutrient analysis and the gravimetric method for solids. An important goal of this project is to accurately quantify the nutrient loads to examine trends on an event, daily and seasonal basis. To evaluate the effect of drainage discharge rates on N and P losses, regression analysis will be conducted between log-transformed values of daily flow rates and daily N and P losses. If the discharge rate has no effect on P concentrations, then the slope of the linear regression would be 1. A slope greater than 1 indicates a "flushing" effect (higher discharge rates cause higher P concentrations) and a slope less than 1 indicates a "dilution" effect (higher discharge rates cause lower P concentrations). To evaluate the effect of time between manure application and N and P loss, regression analysis will be conducted on a daily and per event basis. Event fluxes and flow-weighted concentrations of N and P (dependent variable) will be plotted against the time (days) between manure application and the discharge event. The same analysis will be conducted on a daily time scale (daily N and P loss and daily flow-weighted N and P concentration). Materials will be developed with details on treatment design based on flow conditions from tile drains (which can typically be based on the tile line size) as well as installation and maintenance recommendations determined in the field trial. The documents developed will also include system performance as measured from laboratory media evaluations (removal base on grams of nutrient removal per gram of media) and overall performance in the field. Detailed design data and videos showing construction, maintenance, and operation will also be developed to aide in technology adoption.