Limiting nutrient contaminants from agricultural non-point sources: Nutrient monitoring at EKU’s Meadowbrook Farm, Madison County, Kentucky

Sources of contamination to U.S. waterways have largely shifted from industrial, point sources to agricultural and other non-point sources associated with common human activities. EKU’s Meadowbrook Farm explores best-practices in agriculture and animal husbandry that not only act to increase the efficiency of farm operations, but also to limit environmental effects such as the eutrophification of its neighboring watershed. We recently started a collaboration with the Farm and the EKU Department of Agriculture, which are developing methods to sequester phosphorus and thus limit nutrient export to the adjacent Muddy Creek watershed. Our task is to quantify the amount of phosphorus (mainly as orthophosphate, PO43-) and other nutrients (ammonium, NH4+; nitrate, NO3-) leaving the Farm at key points of egress both before and after sequestration efforts begin. We will then compare initial phosphorus export estimates to those obtained after sequestration begins in order to characterize its utility and effectiveness. Phosphorus export will be directly related to runoff and rainfall events that vary considerably from season-to-season and from year-to-year. We aim to monitor phosphorus (and nitrogen) concentrations over a period of 2-3 years both before and after phosphorus sequestration begins, establishing a monitoring period of 4 to 6 years total. Some preliminary results are given by Buskirk et al., Evans et al., and Kelley et al. at this conference

Mediation of eutrophication of surface and subsurface water from non-point sources: Nutrient monitoring at Meadowbrook Farm (Madison County, Kentucky)

Non-point sources from various human activities such as farming have replaced industrial point sources as contributors of many contaminants in surface and subsurface waters of the United States. Eastern Kentucky University’s Meadowbrook Farm (720 acres, ~2.9 km2; Madison County, Kentucky) is a teaching facility dedicated to improving farming techniques and discovering best practices for farm operations that include minimizing environmental impacts. Agricultural activities on the Farm contribute nutrients to the Muddy Creek (Kentucky River) watershed that promote eutrophication and degrade water quality. Farm management already uses protocols to mediate drainage of dissolved nitrogen off the Farm, but also wants to limit phosphorus contributions by developing a phosphorus sequestration program. To correctly access the success of sequestration, phosphorus export from the farm must be quantified before sequestration efforts begin and then after implementation. For the next several years before phosphorus sequestration begins, we will quantify nutrient export of a representative portion of the farm acreage by measuring stream discharge and nutrients (orthophosphate, PO43-; total phosphorous; nitrate, NO3-; and ammonium, NH4+) over a constructed weir. Once sequestration begins we will continue to monitor nutrient export and compare before-and-after results to test the efficacy of phosphorus sequestration efforts. Our team initiated work to characterize nutrient drainage from the Farm in summer 2016. Geology and farming combine to control runoff and the nutrient content of Meadowbrook Farm waters. Two main overland drainages are developed on the Farm and a series of 10 springs drain into Muddy Creek on the Farm’s southern and eastern borders. Springs emanate from the Boyle Dolomite (Silurian) and often connect to surface drainage, which can then run for as little as 10 m or up to 100’s of meters before entering Muddy Creek. Crop area of the Farm is underlain by a network of tile drains, some of which discharge directly into Muddy Creek whereas others discharge into channels that feed overland drainage. Our team sampled waters from all 3 major sources and from Muddy Creek to assess dissolved nutrient levels with results given as a series of student poster presentations presented at this conference

Characterization of groundwater and surface water geochemistry in an agricultural setting at EKU Meadowbrook Farm, Madison County, Kentucky

Agricultural activities often contaminate watersheds with excess nutrients leading to poor water quality and eutrophication. Eastern Kentucky University (EKU) Meadowbrook Farm raises crops and livestock, which contribute dissolved nutrients to the neighboring Muddy Creek watershed. Consequently, the Farm is developing methods to sequester phosphorous and limit nutrient contamination. Before phosphorous sequestration methods can be tested, Farm surface water and groundwater geochemistry must be better understood to determine hydrological pathways for nutrients. We use naturally-occurring dissolved cations, pH, oxidation-reduction potential (ORP), specific conductivity (SC), dissolved oxygen (DO%), total hardness, and alkalinity as chemical tracers to parse the contribution of dissolved ions from different water sources, to recognize different water source chemistries, and to interpret storm events. To measure discharge from a proximal, intermittent stream that drains a representative and critical portion of the Farm, we used an instrumented, V-notch weir to examine storm-water flow during Tropical Storm Cindy (June 22-25, 2017). Water samples taken from springs (groundwater), surface water, and storm water on the Farm were analyzed for various dissolved constituents. Dissolved cations were measured via ICP-OES (ACT Labs) for sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+). pH, ORP, SC, and DO% were determined with YSI and Vernier probes. Alkalinity and total hardness were measured via the bromocresol green - methyl red and the EDTA digital titration methods, respectively. Dissolved ammonium (NH4+), nitrate (NO3-), and phosphate (PO43-) concentrations were determined by colorimetry with a UV-VIS spectrophotometer via the sodium hypochlorite, cadmium reduction, and ascorbic acid methods, respectively. Both groundwater and surface water sources exhibit similar ranges of pH (neutral to basic), ORP (oxidizing), alkalinity, total hardness, DO%, and SC. Source waters generally have high Ca2+ and Mg2+, and low K+, Na+, PO43-, and NH4+ concentrations. This strongly suggests that background chemistries of source groundwater and surface water are controlled by local limestone bedrock dissolution. Groundwater is further characterized by relatively high NO3- concentrations and low temperatures; in contrast, surface waters exhibit higher temperatures and lower NO3- concentrations. During the Cindy event, concentration of Ca2+, Mg2+, and Na+ within baseline source waters decreased with increasing discharge through the weir (Fig. 1), along with SPC, pH, and alkalinity. This behavior represents dilution of Farm groundwater by storm precipitation and subsequent overland flow. However, K+ increased from baseline concentrations, spiking concurrently with increased discharge through the weir, and then progressively decreased in magnitude over the duration of the storm (Fig. 2). These data suggest that K+ was flushed from soil by rain waters. Nutrient concentrations increase with increased discharge indicating transport by surface runoff. For example, PO43- concentrations closely track and are proportional to discharge, which suggests PO43- transport from the surficial soil substrate via flushing by precipitation (Fig. 3). NO3- exhibited nearly identical transport behavior as K+; concentration spikes occur simultaneously with K+ and discharge. However, NO3- levels reached a higher baseline concentration than pre-storm levels. The Cindy event suggests infiltration and retention of NO3- within soil and groundwater during fair weather, initial flushing during the rain event, and then prolonged NO3- release from Farm soil and groundwater. Background concentration of NH4+ is generally 0.0 to 0.2 mg/L. Immediately prior to water flow over the weir during the Cindy event, concentrations were unusually high (~1.7 mg/L). During the first storm pulse, these high concentrations decreased significantly to \u3c0.4 mg/L. Later in the main storm event, NH4+ tracked discharge from the weir and afterward returned to typical background concentrations. This behavior suggests rapid release of NH4+ from soil followed by accumulation within the weir pool and then subsequent flushing during the precipitation event

Geochemical Characteristics and Storm Dynamics of Surface Waters and Groundwater at Eastern Kentucky University’s Meadowbrook Farm, Madison County, Kentucky

Agricultural activities often contaminate watersheds with excess nutrients leading to poor water quality and eutrophication. Eastern Kentucky University’s Meadowbrook Farm raises crops and livestock, contributing dissolved nutrients to the neighboring Muddy Creek watershed. Consequently, the Farm is developing methods to sequester and limit nutrient contamination. Before phosphorous sequestration methods can be tested, the geochemistry of surface water and groundwater on the Farm need to be better understood to determine hydrological pathways. We use naturally-occurring, dissolved cations as tracers to identify the contribution of different water sources and interpret storm events. Water samples taken from springs (groundwater), surface water, and storm water on the Farm were analyzed for dissolved cations via ICP-OES for sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+). A V-notch weir was used to quantify volumetric flow for a rain event during tropical storm Cindy. Ca2+ and Mg2+ concentrations (55.5-80.0 mg/L and 21.7-32.5 mg/L, respectively) and lower Na+ and K+ concentrations (9.6-14.8 mg/L and 1.7-18.3 mg/L, respectively) seem to predominantly characterize source groundwater. During Cindy, Ca2+, Mg2+, and Na+ decreased with increasing volumetric flow rate, likely indicating dilution of groundwater. However, K+ exhibited elevated concentrations that spike concurrently with initial discharge peaks and then progressively decrease over the duration of the storm event. We hypothesize that initial K+ increases represent significant overland flow followed by dilution with groundwater and/or continued runoff. If nutrient runoff behavior is similar to potassium, those nutrients should exhibit peak export with initial runoff

Patterns of nutrient export for a typical non-point source, Meadowbrook Farm, Madison County, Kentucky

Excess nutrients are found in watersheds originating from active farmland often causing poor water quality and eutrophication in natural waters. Use of fertilizer and animal husbandry can contaminate both surface water and groundwater. Eastern Kentucky University’s Meadowbrook Farm raises crops and livestock and is typical of farms that contribute excess nutrient contaminants to watersheds as non-point sources. An instrumented weir is positioned within a key sub-watershed of the Farm that empties into Muddy Creek, a tributary of the Kentucky River. This drainage is the largest outlet from the Farm that is representative of the Farm’s collective activities. We measured flow and nutrient concentration (orthophosphate, PO43-; nitrate, NO3-; and ammonium, NH4+) over the weir to ascertain flow rates, nutrient export rates, and overall nutrient export. We concentrate on patterns of nutrient export during a single rainy period from 22 to 25 June 2017, which encompasses the passage of the remnants of tropical storm Cindy. In addition, baseline samples were obtained during drier periods throughout that summer. Various nutrients respond differently to storm flow. Dissolved phosphate mirrors the flow hydrograph showing peak concentrations of 0.5, 0.8, 1.2, and 1.0 mg/L correlative with 4 distinct instances of peak flow. Nitrate concentration spikes sharply to ~3.0 mg/L during initial runoff but then quickly decreases and maintains constant values between 1.0 and 1.5 mg/L. Ammonium values are highest, just under 2 mg/L, before initial flow over the weir and then decrease to show sporadic values between 0.1 and 0.6 mg/L, apparently independent of discharge

Nutrient export from a proximal intermittent stream draining EKU Meadowbrook Farm, Madison County, Kentucky

Agricultural activities contribute significant amounts of nutrients that contaminate surface and subsurface water. Eastern Kentucky University (EKU) Meadowbrook Farm (Madison County, Kentucky) seeks to decrease its export of nutrients to Muddy Creek using sequestration techniques. The first step in the overall process is to determine nutrient export at present, before sequestration efforts take place. Here we estimate the export of phosphate, nitrate, and ammonium during Tropical Storm Cindy (July 22 to 24, 2017) from a proximal, intermittent stream, named the BRC. This stream drains a representative portion the Farm, receiving water from a dairy complex, pasture, and cropland. To estimate nutrient export, both discharge and nutrient concentration must be determined. We have built a V-notched weir across the BRC drainage equipped with a datalogger that measures water elevation behind the dam, and an autosampler that captures water samples during rain events. Water level and discharge over the dam are proportional, so that discharge can be calculated during rain events. Nutrient concentration is measured for each water sample using accepted colorimetric methods: ascorbic acid (phosphate), cadmium reduction (nitrate), and sodium hypochlorite (ammonium). Once discharge and nutrient concentrations are measured for the rain event, total nutrient mass can be calculated from the resultant curves (Fig. 1). Discharge and concentration data were parsed into 30-second time steps over the course of the entire, 72-hour rain event, and we used a cubic spline application (grafted into MS Excel) to produce a continuous function for each parameter. The area under the discharge and concentration curves yielded total solute mass for the Cindy event. Based on these data and using the cubic spline technique, we estimate that the export of phosphorus was 3.1 kg P occurring as dissolved orthophosphate, and 6.3 kg N occurring as dissolved nitrate (5.3 kg) and ammonium (1.0 kg) during Cindy. We also intend to determine the amount of total phosphorus (orthophosphate, other forms of dissolved phosphorus, P contained within dissolved organics, and P adsorbed onto fine particulates) exported during Cindy, as well as estimating nutrient export for five other rain events captured during 2017

Nutrient contamination from non-point sources: Dissolved nitrate and ammonium in surface and subsurface waters at EKU Meadowbrook Farm, Madison County, Kentucky

Agricultural activities often contaminate watersheds with excess nutrients leading to poor water quality and eutrophication. We assayed dissolved nutrient levels in surface and subsurface waters of Eastern Kentucky University’s Meadowbrook Farm in order to assess levels of dissolved nutrients leaving its farmland and draining into the Muddy Creek watershed. The Farm raises both crops and livestock so that nutrient sources include fertilizer and manure. We sampled springs, runoff, and subsurface pipe drainage as well as Muddy Creek on six days from May to August 2016 under a variety of weather conditions. Using established, standard colorimetric methods, we measured nitrate (NO3-; cadmium reduction method) and ammonium (NH4+; sodium hypochlorate method) via spectrophotometry with a precision and accuracy of ~0.1 mg/L. Nitrate was the dominant dissolved nitrogen species whereas ammonium was often absent in water samples. Nitrate levels were typically \u3c2 mg/L N- N- NO3 with the largest values between 7.0 and 14.3 mg/L. Springs and some runoff samples had higher nitrate values. Ammonium generally ranged between 0.0 and 0.5 mg/L N- NH4 with concentration spikes between 2.0 and 4.3 mg/L, but from no consistent source. Dissolved nitrogen concentration values responded to rainfall. Generally, nitrate concentrations increased more than ammonium concentrations during wetter periods. Spring samples maintained higher nitrogen concentrations regardless of different rainfall conditions. Lastly, nitrate contamination was significantly lower than composite national values from streams draining agricultural lands, whereas ammonium was about equal to the median national average. Median nitrate concentration was ~1.8 mg/L N- NO3 compared to the national value of ~2.8 mg/L, whereas the value for pristine streams is 0.24 mg/L N- NO3 (Dubrovsky et al., 2010). Median ammonium values from both data sets are ~0.1 mg/L N- NH4; the national value from pristine streams is ~0.025 mg/L N

Dissolved nitrogen (nitrate and ammonium) in surface and groundwater at EKU Meadowbrook Farm, Madison County, Kentucky

Agricultural activities often contaminate watersheds with excess nutrients, leading to poor water quality and eutrophication. Eastern Kentucky University’s Meadowbrook Farm is no exception, and contributes dissolved nitrogen into the Muddy Creek watershed. To assess concentrations of dissolved nitrogen compounds, we sampled waters draining from the farm: springs, runoff, and subsurface pipe drainage as well as Muddy Creek. These water samples were collected on eight days from May through August 2016 under a variety of weather conditions. We measured dissolved nitrate and ammonium using the standard cadmium reduction and sodium hypochlorite methods via colorimetric spectrophotometry with an accuracy and precision ~0.1 mg/L. Nitrate was usually the dominant nitrogen compound, higher ammonium levels occurred only sporadically. Typically, nitrate levels were \u3c2 mg/L with largest values from 7 to 14.3 mg/L. There were few differences in nitrate concentrations in water samples from different sources. However, springs sometimes had higher nitrate concentrations than Muddy Creek and runoff samples. Tributary 6E, draining off-farm areas to the east, consistently had the highest levels of dissolved nitrate relative to other sources. Ammonium values were generally between 0 and 0.5 mg/L. Concentration spikes between 2.0 and 4.3 mg/L occurred, but from no consistent source. We generally did not see consistent patterns of increasing or decreasing nitrate and ammonium concentration with respect to sample type, nor any firm connection with rainfall events. However, in one instance two days after a significant rainfall, higher nitrate and ammonium values were observed in all sample types

Nutrient contamination from non-point sources: Dissolved phosphate in surface and subsurface waters at EKU Meadowbrook Farm, Madison County, Kentucky

Farms are non-point sources for nutrient contaminants that drain into watersheds and contribute to eutrophication and other environmental problems. Eastern Kentucky University’s Meadowbrook Farm raises both crops and livestock, causing dissolved phosphorus in the form of orthophosphate (PO43-) from fertilizer and animal manure to enter surface and subsurface waters, eventually flowing into Muddy Creek, a tributary of the Kentucky River. We sampled surface water, springs, and water from French drains that emanate from the farm, and also sampled Muddy Creek waters from May through August 2016. Typically, 1 to 2 days after sampling, we colorimetrically measured dissolved orthophosphate concentration using the established ascorbic acid method and a UV-VIS spectrophotometer with general accuracy and precision of ~0.1 mg/L, or ppm. Phosphate values measured from the farm are less than those measured nationally from agricultural lands. The median value of orthophosphate from Farm waters was 0.02 mg/L P-PO4, but nationally the level is ~0.1 mg/L P-PO4; pristine water display 0.010 mg/L P-PO4. Phosphate concentrations are also low when compared to nitrate usually ranging from 0 to 0.2 mg/L P-PO4 with higher concentrations of 0.5 to 2.7 mg/L P-PO4 occurring sporadically. With minor exceptions, we saw little difference in phosphate concentration between different sample sources whether spring water, water from subsurface drains, surface waters flowing over the Farm, or Muddy Creek waters. However, one sub-watershed draining the Farm had increased levels of phosphate on 24 May (2.7 mg/L P-PO4). Overall patterns of phosphate concentration were similar whether sampling during periods with little or no rainfall, or periods following rain events. An exception occurred on 24 June, when overland waters of the same sub-watershed mentioned above had a value of 0.5 mg/L, immediately following a significant rain event

Nutrient contamination from non-point sources: Dissolved nitrate and ammonium in surface and subsurface waters at EKU Meadowbrook Farm, Madison County, Kentucky

Agricultural activities often contaminate watersheds with excess nutrients leading to poor water quality and eutrophication. We assayed dissolved nutrient levels in surface and subsurface waters of Eastern Kentucky University’s Meadowbrook Farm in order to assess levels of dissolved nutrients leaving its farmland and draining into the Muddy Creek watershed. The Farm raises both crops and livestock so that nutrient sources include fertilizer and manure. We sampled springs, runoff, and subsurface pipe drainage as well as Muddy Creek on six days from May to August 2016 under a variety of weather conditions. Using established, standard colorimetric methods, we measured nitrate (NO3-; cadmium reduction method) and ammonium (NH4+; sodium hypochlorate method) via spectrophotometry with a precision and accuracy of ~0.1 mg/L. Nitrate was the dominant dissolved nitrogen species whereas ammonium was often absent in water samples. Nitrate levels were typically \u3c2 mg/L N- N- NO3 with the largest values between 7.0 and 14.3 mg/L. Springs and some runoff samples had higher nitrate values. Ammonium generally ranged between 0.0 and 0.5 mg/L N- NH4 with concentration spikes between 2.0 and 4.3 mg/L, but from no consistent source. Dissolved nitrogen concentration values responded to rainfall. Generally, nitrate concentrations increased more than ammonium concentrations during wetter periods. Spring samples maintained higher nitrogen concentrations regardless of different rainfall conditions. Lastly, nitrate contamination was significantly lower than composite national values from streams draining agricultural lands, whereas ammonium was about equal to the median national average. Median nitrate concentration was ~1.8 mg/L N- NO3 compared to the national value of ~2.8 mg/L, whereas the value for pristine streams is 0.24 mg/L N- NO3 (Dubrovsky et al., 2010). Median ammonium values from both data sets are ~0.1 mg/L N- NH4; the national value from pristine streams is ~0.025 mg/L N