Presentations 2016

The Central Valley Dairy Representative Monitoring Program – Insight from 4 Years of Monitoring and Special Studies

LSCE

https://www.youtube.com/watch?v=gIeTgBx9ToM&list=PLZC-5vj9_JAYJ9uI2abX-KQy56Nl6HTmI&index=1

Since 2012, the Central Valley Dairy Representative Monitoring Program (CVDRMP) has been implementing a regulatory compliance groundwater monitoring program in the Central Valley of California spanning over 600 kilometers from north to south. The climate is semi-arid with hot, dry summers and cool winters with the majority of precipitation occurring between November and March. CVDRMP represents over 1,100 dairies, diverse soil and farming conditions, and collects data in over 430 dedicated monitoring wells adjacent to animal housing, earthen liquid manure storage lagoons, and fields where both liquid and solid manure is applied to fertilize forage crops. The program is tasked to identify farming practices that are protective of groundwater quality and formulate recommendations in 2019.Four years of groundwater monitoring have confirmed impacts to shallow groundwater quality associated with dairy operations. Elevated nitrate concentrations and salinity are ubiquitous and impart a trademark on groundwater similar to other, non-dairy agricultural operations. However, the overall utility of groundwater monitoring has been found to be limited.Regulatory attention was initially focused on lagoons. The program found that groundwater monitoring is not an effective means of investigation in the context of lagoons. Groundwater constituent concentrations do not yield information on concentrations in the leachate, the seepage rate, the overall mass loading rate, or the duration of the loading. To address this issue, CVDRMP conducted a comprehensive field investigation quantifying whole lagoon seepage rates. Seepage rates were small, ranging from zero to 2.2 mm d-1, with a mean and median of 1.0 and 0.7 mm d-1, respectively (n=16). Lagoons ranged in age from less than 10 to over 50 years, i.e., many of them predated regulations or guidance for lagoon liner design. Subsurface soil textures ranged from sand to silty clay, but seepage rates did not correlate well to soil texture. One lagoon, where exposed gravel strata are suspected, had a seepage rate of 3.9 mm d-1 when at full capacity. Seepage rates and the mean nitrogen mass loading rate of 1,172 kg ha-1 y-1 were consistent with findings of other research efforts. Complementary soil borings and geophysical methods documented that effects of lagoon seepage on groundwater quality are generally small and remain localized. Based on preliminary land base and unit loading rate estimates from 41 dairies, lagoon contributions were estimated to be 2.3-3.5 percent on a farm scale compared to 96.5-97.7 percent from crop fields (animal housing including corrals not included)The program identified groundwater monitoring as similarly ineffective in the context of assessing farming practices on the crop fields. Improvements in agricultural practices, including improved nutrient use efficiencies, manifest themselves in reduced subsurface nitrogen and salt mass emissions; this reduction is not necessarily observed in concentration decreases at the water table. To address this issue, CVDRMP is carrying out several research studies tackling the difficult task of nutrient management in full-scale production systems that heavily rely on organic sources (i.e., manure) for fertilization.

What Will It Take To Protect Groundwater Quality Under California Central Valley Dairies?

University of California Cooperative Extension

https://www.youtube.com/watch?v=HjLepIlrC8I&index=2&list=PLZC-5vj9_JAYJ9uI2abX-KQy56Nl6HTmI

There is ample evidence of elevated nitrate concentrations in groundwater under dairies in the Central Valley of California, however solutions to this issue have been elusive. Regulations put in place may have raised awareness among dairy operators, and may have resulted in improved nutrient management, but have not resulted in the level of improvement necessary to protect groundwater quality. Work done in a 10-year study showed that while decreasing the amount of manure applied did result in a decrease in shallow groundwater nitrate concentrations, yields could not be maintained unless the amount of manure and other nitrogen applied exceeded what is now the regulatory limit of 1.4 times crop removal. Many dairy producers now find themselves in the position of being unable to maintain their production levels and still stay within the regulatory limits. Without access to improved nutrient management techniques and technologies, additional education and potentially changes in the regulatory system, dairy operators face the real possibility of being forced to move their dairies out of state or leave the dairy business.Many factors limit a dairy operator’s ability to maintain production using only manure nitrogen forms. They include sandy soils with poor ability to retain nutrients, irrigation systems that cannot apply water at rates that minimize leaching of nitrates, fluctuating lagoon nitrogen concentrations, difficulty and complexity of measuring, recording and calculating application rates, uncertainties in predicting and accounting for manure and soil organic nitrogen availability, inadequate land base for the amount of manure generated, and limited economic resources to implement improvements even where proven technology exists.Solutions to these issues will be different for different regions and dairies within regions; there is no one approach that will fit all situations. However, in general, an effective nutrient management system on a dairy would include these essential components: • Reasonable irrigation efficiency and uniformity to prevent excessive leaching. • Accurate measurements of irrigation water and nutrient inputs, and nutrient harvest removal• Ability to apply specific amounts of manure nutrients at the target rates and times they are needed• On-farm record keeping which provides timely in-season computation of application amounts • Decision support for estimating organic N release, expected leaching losses and other dynamic nitrogen processes throughout the year both to make an application plan and to identify the need for in-season adjustments.Implementation of each of these components has significant challenges, and in many cases the technology and science are currently inadequate or nonexistent. In addition, our experience is that there are many additional unforeseen issues that will need to be addressed on an individual basis for each dairy. Even when the best technology is implemented to minimize leaching through irrigation improvements, groundwater quality may not improve enough to meet regulatory expectations because some leaching is unavoidable and necessary to prevent salt buildup in the soil, and the nitrate and salt concentration in the reduced amount of leachate would be expected to be high.

Evaluating the influence of tile drainage management on shallow groundwater resources

Aquanty

https://www.youtube.com/watch?v=tIVsKm_HMJ8&index=3&list=PLZC-5vj9_JAYJ9uI2abX-KQy56Nl6HTmI

Picture Not Available

Tile drainage management is considered a beneficial management practice (BMP) for reducing nutrient loads in surface water. Previous research has shown that controlling tile discharge via control structures with adjustable stop gates can be very effective for reducing tile discharge volume, and that on an annualized basis there is often a reduction in nitrate loads that is proportional to the reduction in discharge. However, the influence of controlled drainage on groundwater resources is rarely considered. In this presentation we will discuss tile drainage experiments that were conducted in Ontario, Canada, that were designed to assess the influence of drainage management on the movement of nutrients and rhodamine WT to surface water and groundwater under controlled (CD) and free drainage (FD) tile management. We will also present results from 2-dimensional dual permeability modeling that was conducted to help develop a better understanding of the flow and transport processes within the soil profile and shallow groundwater system under different drainage management scenarios. Results from the modeling demonstrate that dominant flow and transport characteristics at the field site were successfully replicated, including higher, more continuous tile discharge and lower peak rhodamine concentrations in FD tile effluent; as compared to CD, where discharge was intermittent, peak rhodamine concentrations higher, and mass exchange from macropores into the soil matrix greater. Explicit representation of preferential flow in the modeling framework was essential, as macropores were shown to transmit > 98 % of surface infiltration, tile flow, and tile solute loads for both FD and CD. Incorporating an active 3rd type boundary across the bottom of the model domain in order to facilitate shallow groundwater outflow was imperative for simulating CD, as the higher (relative to FD) water table facilitated greater water and soluble nutrient movement from the soil profile into deeper groundwater. Scenario analysis revealed that in conditions where slight upwards hydraulic gradients exist in tile drained settings, groundwater upwelling can dilute the concentration of surface derived solutes under FD conditions; whereas the higher and flatter water table associated with CD can act to reduce groundwater upwelling. Results show that while CD can reduce tile discharge, and soluble nutrient loads and concentrations in tile effluent and hence surface water receptors, it can promote NO3 loading into groundwater.

Investigating Livestock Manure Storage Facility Impacts on Groundwater in Alberta, Canada

Natural Resources Conservation Board

https://www.youtube.com/watch?v=jqou347kZeQ&list=PLZC-5vj9_JAYJ9uI2abX-KQy56Nl6HTmI&index=4

In January 2002, the Alberta Government assumed responsibility for the regulation of confined feeding operations (CFOs) when the Agricultural Operation Practices Act (AOPA) was amended. The Natural Resources Conservation Board (NRCB), the Provincial agency responsible for the administration of the AOPA, and Alberta Agriculture and Forestry (AF) are concerned that some manure storage facilities and associated activities, such as land application of manure, may be releasing manure constituents into shallow groundwater resources. An integral part of the administration of the AOPA is determining environmental risk, as outlined in a provincially adopted Risk Management Framework policy. This has lead to the development and use of a risk screening tool and risk based compliance initiative, both currently focused towards groundwater. Although the environmental risk based policy being implemented utilizes the best available, current, and relevant science, limited Alberta-specific information exists on the impacts of manure storage and handling on groundwater quality, leading to uncertainty in the actual extent and risk that these activities pose to groundwater. As Alberta is home to almost 50% of Canada’s beef cattle population, as well as a significant proportion of the national dairy, pork, and poultry populations, Alberta-specific understanding is important to the overall knowledge base.A multi-year groundwater research program was conducted through the establishment and instrumentation of field-scale CFO pilot study sites to improve the understanding of impacts from manure handling and storage on groundwater quality in Alberta and the fate and transport of various manure constituents in groundwater beneath CFOs. Long-term study sites were identified through site characterization, geological investigations, and monitoring well installation, and represent the primary typical hydrogeological conditions in Alberta affected by manure storage and handling activities. Activities were focused at specific earthen manure storage (EMS) facilities at site specific CFOs, and were also designed to examine the effects of manure land application and on a regional scale on Alberta’s groundwater.Research program activities included characterization of the contaminant (i.e., aqueous) source, characterization of the hydrogeological and physical controls on the transport of contaminants, characterization of the background aqueous and solids chemistry, characterization of aqueous and solids chemistry within the contaminant plume, and quantification of the geochemical controls on the fate of contaminants. Results and findings will be presented. By improving the scientific and practical understanding of the fate and transport of manure constituents in the groundwater in typical Alberta CFO settings, improved management, policy, regulation, and protection of the groundwater and environment can be achieved. The results also provide insights and understanding into the impacts of other point- and non-point-sources of manure associated contamination, particularly land application of inorganic and organic fertilizers and disposal of human waste, on Alberta groundwater. Instrumentation installed may also provide the opportunity to investigate the fate and transport of other emerging contaminants (e.g., pharmaceuticals, viruses, etc.) and thus assess their impact on groundwater.

Stable isotopes as indicators of sources and processes influencing nitrate distributions in groundwater beneath dairy farms in California

United States Geological Survey

https://www.youtube.com/watch?v=vLMllROO9NQ&list=PLZC-5vj9_JAYJ9uI2abX-KQy56Nl6HTmI&index=5

Dairies represent the majority of animal feeding operations in California, and have been shown to be potential sources of nitrate and salinity, dissolved organic carbon, and pathogens to groundwater. In California’s Central Valley, nitrate contamination of drinking water wells is a significant concern, and there are multiple sources of nitrate including septic discharge, synthetic and manure fertilizers, and concentrated animal feeding operations. In order to better understand the potential contributions of dairy manure derived nitrate to both shallow and deep groundwater, we used a combined geochemical and stable isotope approach for water samples collected from a network of shallow groundwater monitoring wells on several California dairies located in two distinct geographic regions. In the northern region, the lower San Joaquin Valley, the water table is shallow (2- 5 m below surface) and therefore considered highly vulnerable to contamination, while in the southern region, the Tulare Lake Basin, the water table is much deeper (20 - 30 m).In each dairy, nitrate isotopes, water isotopes, nutrient concentrations, and other chemical and physical parameters were measured in monitoring wells located within different land use areas of the dairies. Monitoring wells were classified by the dairy-related land uses of corrals, fields receiving manure, waste lagoons, and mixed land use (undetermined). Across all sampled dairy monitoring wells, d15N-NO3 ranged from +2.9 to +49.4‰, and d18O-NO3 ranged from -3.3 to +19.2‰. Mean nitrate concentrations, nitrogen isotopic composition, and oxygen isotopic composition were significantly higher in the northern (Stanislaus County) dairy wells in comparison to the southern (Kings and Tulare Counties) dairy wells. Nitrate isotope measurements indicated that many of the northern monitoring wells had consistently high contributions of manure-derived nitrate to the shallow groundwater during the 16 month study. Monitoring wells located in relatively new dairies in the south region showed little evidence of manure-derived nitrate, while those located in much older dairies in the south region showed a very wide range of nitrate isotope values, indicating significant nitrate contributions from multiple sources including manure and industrial fertilizer and biological processing effects. Combined nitrate concentration and isotopic data from all the monitoring wells showed very little evidence of significant saturated-zone denitrification. Monitoring well networks within individual dairies showed wide ranges of nitrate concentrations, nitrate isotopic compositions, and geochemical compositions, confirming the heterogeneity of the nitrate loading across dairy facilities and indicating that measurements from any single monitoring well may not be representative of general groundwater quality downgradient of an individual dairy.