Stetson Soil Analysis: Testing Nutrient Concentrations and PH in Fertilized and Unfertilized Landscapes

STETSON SOIL ANALYSIS: TESTING NUTRIENT CONCENTRATIONS AND PH IN FERTILIZED AND UNFERTILIZED LANDSCAPES A PAPER SUBMITTED FOR COMPLETION OF SENIOR RESEARCH FOR THE COLLEGE OF ARTS AND SCIENCES STETSON UNIVERSITY BY Sara Nelmes IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF BACHELOR OF SCIENCE ENVIRONMENTAL SCIENCE AND GEOGRAPHY ADVISOR Dr. Jason M. Evans, Ph.D. MAY 2017 i Table of Contents: Table of Contents: Table of Contents: Table of Contents: Table of Contents: Table of Contents: Table of Contents: ii. List of Illustrations iii. List of Tables iv. Acknowledgments v. Abstract pg. 1. Introduction pg. 2-5. Literature Review pg. 5. Methods pg. 7 Results/Analysis pg. 12 Conclusions and Discussion pg. 14 Appendix pg. 16 Works Cited ii List of List of List of IllustrationsIllustrations Illustrations Illustrations Illustrations: Figure 1.1Figure 1.1 Figure 1.1 Nitrogen Concentrations in Stetson Soils Nitrogen Concentrations in Stetson Soils Nitrogen Concentrations in Stetson Soils Nitrogen Concentrations in Stetson Soils Nitrogen Concentrations in Stetson Soils Nitrogen Concentrations in Stetson Soils Nitrogen Concentrations in Stetson Soils Nitrogen Concentrations in Stetson Soils Nitrogen Concentrations in Stetson Soils Pg. 8Pg. 8Pg. 8 Figure 1.2Figure 1.2 Figure 1.2 Phosphorus Concentrations in Stetson SoilsPhosphorus Concentrations in Stetson Soils Phosphorus Concentrations in Stetson Soils Phosphorus Concentrations in Stetson SoilsPhosphorus Concentrations in Stetson SoilsPhosphorus Concentrations in Stetson Soils Phosphorus Concentrations in Stetson Soils Phosphorus Concentrations in Stetson Soils Phosphorus Concentrations in Stetson SoilsPhosphorus Concentrations in Stetson Soils Phosphorus Concentrations in Stetson Soils Phosphorus Concentrations in Stetson Soils Phosphorus Concentrations in Stetson Soils Phosphorus Concentrations in Stetson Soils Pg.Pg.Pg. 9 Figure 1.3Figure 1.3 Figure 1.3 pH in Stetson Soils pH in Stetson Soils pH in Stetson Soils pH in Stetson Soils Pg. 9Pg. 9Pg. 9 Figure 2.Figure 2. Figure 2. 1 Changes in Nitrogen Concentrations Changes in Nitrogen Concentrations Changes in Nitrogen Concentrations Changes in Nitrogen Concentrations Changes in Nitrogen Concentrations Changes in Nitrogen Concentrations Changes in Nitrogen Concentrations Changes in Nitrogen Concentrations Changes in Nitrogen Concentrations Changes in Nitrogen Concentrations Changes in Nitrogen Concentrations Changes in Nitrogen Concentrations Stetson Soils over Time Stetson Soils over Time Stetson Soils over TimeStetson Soils over Time Stetson Soils over TimeStetson Soils over Time Stetson Soils over Time Pg. 10Pg. 10Pg. 10 Figure 2.2Figure 2.2 Figure 2.2 Changes in Phosphorus Concentrations Stetson Soils over TimeChanges in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over TimeChanges in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over TimeChanges in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over TimeChanges in Phosphorus Concentrations Stetson Soils over Time Changes in Phosphorus Concentrations Stetson Soils over Time Pg. 11Pg. 11Pg. 11 Figure 2.3Figure 2.3 Figure 2.3 Changes in pH Stetson Soils over TimeChanges in pH Stetson Soils over Time Changes in pH Stetson Soils over Time Changes in pH Stetson Soils over Time Changes in pH Stetson Soils over Time Changes in pH Stetson Soils over TimeChanges in pH Stetson Soils over Time Changes in pH Stetson Soils over TimeChanges in pH Stetson Soils over Time Changes in pH Stetson Soils over Time Pg. 11Pg. 11Pg. 11 iii List of Tables: Table 1. ANOVA Results for Nitrogen Pg. 14 Table 2. ANOVA Results for Phosphorus Pg. 15 Table 3. ANOVA Results for pH Pg. 15 iv Acknowledgements: I would like to acknowledge my advisors, Dr. Jason Evans and Dr. Wendy Anderson, for advising my research, helping me collect the soil samples, perform the lab analysis, and run the statistical analyses; my peers for reviewing my work and for giving me feedback and support; David Rigsby and Chad Richards from the Stetson Grounds Department for providing information and guidance on the project and their fertilizer and pesticide use; and my family and friends for helping me collect soil samples and for providing support. v Abstract: Fertilizers applied to highly managed landscapes can generate excess nutrients that pollute surface water or groundwater. Fertilizer-derived nutrients are identified as one of the leading contributors to algal blooms, which can block sunlight and ultimately deplete oxygen. Given Stetson’s commitment to environmental stewardship, I asked if the fertilizers that Stetson applies on the Stetson Green are migrating through the soil into the groundwater system. I analyzed the pH and concentrations of total nitrogen (N), phosphorus (P), and potassium (K) in soils from the Stetson Green (fertilized) and the Restored Sandhill Ecosystem (unfertilized control) at depths of 2” (root zone) and 6” (below root zone) over three weeks. I hypothesized that if the Stetson Green is overfertilized, then nutrients will migrate from the 2” zone to the 6” zone over time. The N concentrations in the fertilized Stetson Green were higher than in the unfertilized Sandhill site at both depths, and were highest in the 2” zone in Week 1, shortly after a fertilizer application. However, by Weeks 2 and 3, N had declined significantly in both the 2” and 6” zone, and were more like the Sandhill. The P concentrations were only higher in the 2” zone compared to the 6” zone and both zones in the Sandhill. These P concentrations in the Green’s 2” zone remained high across all 3 weeks, even as they declined over time in the 6” zone. Potassium and pH were not significantly different between sites, depth, or over time. These results indicate that N and P are present in higher concentrations in the soils of the fertilized Stetson Green, but have different fates over time. Nitrogen concentrations decline in the root zone but do not increase over time below the root zone, suggesting that the N is taken up by the roots of the grass or is volatilizing into the air. Phosphorus remains in the 2” root zone over the 3-week period, either because plants take it up more slowly, or because it does not migrate as easily through the soil. There was no evidence that any nutrients are migrating to soil depths below the root zone where they might eventually pollute groundwater supplies.1 Introduction: Fertilizer pollutes lakes, streams and the groundwater with nutrients in fertilizers that cause algal blooms, which keep oxygen and sunlight out of the water bodies and cause death among the living organisms in the ecosystem. In my research, I analyzed how regulated fertilizer application is at Stetson University by testing the nitrogen and phosphorus levels as well as pH of a fertilized area on campus compared to an unfertilized area. My research was done to seeks answers to how Stetson manages its lawns and what we can do as a campus to continue to improve our landscaping in a sustainable and effective way. Many grasses and reclaimed water irrigation systems already contain phosphorus, so fertilizers, at least with amounts that exceed the Redfield ratio, which measures phosphorus levels compared to what is needed for growth, are typically unnecessary (Denny et. al. 2016). Nitrogen tends to either volatilize into the air, move through the soil into the groundwater, or be taken up through the roots of plants. Phosphorus is less likely to move through the soil because of its chemical composition. The fate of nutrients depends on many different factors including irrigation nutrients, soil pH, and soil management. In order to determine how the nitrogen and phosphorus nutrients move through the soil in both the Sandhill and the Stetson Green, I tested three hypotheses in this study. The first hypothesis is if the Stetson Green is fertilized, then its soils will have higher concentrations of nitrogen, phosphorus, and potassium than the unfertilized area (the Sandhill). The second hypothesis looks at how depth affects nutrient levels: if the Stetson Green is over-fertilized, then it will have higher concentrations of nitrogen, phosphorus, and potassium at six-inch depths (below root zone) than two-inch depths, compared to the Sandhill. The third hypothesis compares nutrient concentrations between depths over a three-week period after fertilizer application: if the Green is over-fertilized, then, over a three-week period, nitrogen and phosphorus will migrate from the two-inch depth to the six-inch depth. Nitrogen and phosphorus concentrations will decline over time in 2 the two-inch zone, but increase over time in the six-inch zone, compared to the Sandhill. Using a soil sampling kit, I recorded the concentrations of various nutrients such as total nitrogen, phosphorus, and potassium in our lawns, specifically the Stetson Green and the Native Plant Area behind the Gillespie Museum. The samples were tested on Stetson's campus using new HACH soil testing kits that the Environmental Science department has recently acquired with the help of Dr. Anderson. The results for potassium were negligible and did not affect my study. The results of my study will be used to educate the students, faculty, and staff on how the Stetson campus affects Florida waterways, and promote positive changes in our thoughts and practices concerning our lawn care. Literature Review: Non-point pollution is a major problem and learning about nutrient management is an important aspect in ending water pollution from nutrient runoff. The fate of the nutrients, whether they leach into the groundwater, runoff into surface waters, are taken up by the plants, or volatize into the atmosphere largely depends on the amount, rate, source, and timing of fertilization (Petrovic 1990). Fertilizers are not always necessary for plant growth and we must be proactive with our research and planning to appropriately apply fertilizers. There are management strategies to keep nutrients from leaching into ground water or running off into surface water, including managing the types of plants that are planted and making sure to test the soil for nutrients and pH so that the nutrients are taken up by the plant effectively. According to the USDA Natural Resources Conservation Service, one limiting factor in plant uptake of nutrients is pH, which can hinder the uptake of phosphorus if it is below 5.5 or between 7.5 and 8.5 (Anonymous Date of Publication unknown). The USDA Natural Resources Conservation Service suggests increasing phosphorus availability by “managing by liming acid soils, using measures that increase organic matter, and proper placement of P fertilizer affecting how efficiently P is used by crops. P losses can be reduced by applying appropriate measures to reduce erosion and runoff.” 3 (Anonymous Date of Publication unknown). One common measure of nutrients in soil is the Redfield ratio is a commonly used ratio that determines whether there are excessive amounts of phosphorus in the soil. If there is more than a thirteen to one ratio for nitrogen to phosphorus, then it is safe to say that there is an excess of phosphorous in the soil (Cleveland 2007). In another study that was performed, the water bodies that were upstream from where the nutrient test was performed showed a reduction in phosphorus levels, which shows that the fertilizer ordinance works in that area (Bell 2011). Total dissolved phosphorus was reduced in the area protected by the fertilizer ordinance. Volusia County utilizes a fertilizer ordinance, but there is still much research to be done on lawn management to lessen nutrient pollution of local waterways and groundwater. Pollutants can affect large areas of people who use water bodies for drinking water, fishing and other needs. The U.S. Department of Agriculture and the Environmental Protection Agency proposed new nutrient management practices that manage phosphorus and nitrogen in fertilizers to minimize algal blooms in lakes and rivers, including creating buffers for the plants so that the nutrients will not run-off into the surface waters, applying the proper amount of fertilizer with a proper method, and drainage water management to keep fertilizers out of the surface and groundwater (Anonymous 2016). Another topic that influenced my research is the “P-index.” The “P-index” that was proposed was widely adopted and measures the loss of phosphorus from the soil, so that areas can know how much they must improve their management practices. The index takes into consideration how close the area is to a body of water and the release time of the fertilizer to account for nutrient runoff and leaching. Creating buffers, changing the timing of release and using fertilizers with less nitrogen and phosphorus and fertilizing less often are all ways of reducing nutrients in groundwater (Beegle et. al. 2003). Also, reclaimed water adds significant amounts of nitrogen and phosphorus into the soil, so Stetson and the City of DeLand can possibly use that knowledge to make a more comprehensive 4 solution to the complex problems that our groundwater and waterways are facing here in Florida and around the country. Nutrient overloading is a problem that faces our waterways and can be avoided by managing our fertilizer use and the nutrient uptake of plants by monitoring the pH of the soil and how much fertilizer we can use There is a lack of research on phosphorus and the fate of the nutrients, which depends on the rate, source, and timing of fertilization. Turfgrasses have not been studied as much as agricultural runoff, which is surprising because turfgrass takes up so much space in our country due to large suburban populations. The lawn culture that started in the 1930s and 1940s has pervaded the country and continued to keep the fertilizer and pesticide industries in business, but Stetson’s use of native plants and organic pesticides is a step towards environmentalism (Robbins 2007). Lawn management practices can affect the health of the ecosystem, which is relevant to my own research because I am observing how lawn fertilizers and the management of a university lawn compares to a native plant area that is not irrigated or fertilized (Cheng et. al. 2008). Nitrogen often volatilizes into the atmosphere and therefore can be difficult to find in the results of soil tests, but it can also leach into the soil if used in fertilizers in large amounts that are released quickly into the soil. The article, Nitrogen Retention in Urban Lawns and Forests, suggests that while lawns are large sources of nitrogen that can affect water quality, they can also be considered nitrogen sinks because of precipitation events and atmospheric nitrification. Between lawns and forests, lawns have longer nitrogen retention times but higher rates of nitrification and mineralization (Raciti et. al. 2008). However, nitrogen can wreak havoc on water ecosystems when it volatilizes and turns into nitrate. Ammonium nitrate is also an air pollutant that affects many parts of the environment and public health concerns. Keeping excessive nitrates and phosphorus out of our waterways is essential to 5 keeping ecosystems healthy and stable and continuing to provide clean drinking water to an ever-growing population in the Central Florida area. The University of Florida Extension gives specific nitrogen amounts that are necessary for each grass type that is most common in Florida. Many soils and lawns in Florida naturally have enough phosphorus naturally in them for grasses to uptake, so little to no phosphorus needs to be applied, which is something that I tested by taking samples and analyzing the nutrient concentrations (Shaddox 2015). Stetson University uses Best Management Practices that are set up by the University of Florida Extension Agency, which means that they are trained to fertilize and irrigate based on the climate and terrain of the area. The sandy soils in Florida can easily cause leaching into the groundwater and causes the need for my study to be even more relevant to Stetson’s commitment to environmental stewardship. Methods: My goal was to test the soils for pH, nitrogen, phosphorus, and potassium in each sample that accounts for two different depths and two sites. Collecting the soil samples for analysis was the first step in my project. I used a soil core extractor to reach the top soil (2 inches) as well as below the ground about six inches. In the lab, I tested for levels of nitrogen, phosphorus, potassium, and pH. The type of soil and location where sample was taken will also be identified on each sample bag. In the lab, the soil was dried and tested for its physical and chemical characteristics. My samples were taken from the Sandhill landscape behind the Gillespie Museum, which is unfertilized and not irrigated and the Stetson Green, which is fertilized and irrigated. 6 I took samples right after the Stetson Grounds Department fertilized and then did analysis of nutrient concentrations at different depths throughout the next three weeks after fertilizing. David Rigsby, the Director of Grounds, met with Dr. Anderson and I to discuss my project and how to make it an effective project for the Stetson campus. The samples from the Native Plant area were taken at the same time as the samples from the Stetson Green. We took six samples per site per sampling day over the course of three weeks, which adds up to a total of thirty-six samples. We Took six samples (one from each depth in three locations) over a three-week period after fertilization from each site Within each sampling area, we took samples from 0”-2” and 4”-6” from three sampling areas using a soil core. Core sections were dried for at least 3 days and then sifted to remove rocks and detritus. This provided approximately 50-100 ml of soil per sample after drying and sifting. The combined core sections were dried for at least 3 days and then sifted to remove rocks and detritus. This provided approximately 50-100 ml of soil per sample after drying and sifting. With the help of the Department Chair, I tested the samples with the new HACH soil-testing kits that the Environmental Science Department has acquired. HACH kits are “designed for economical on-site evaluations of soil fertility, the NPK-1 test kit provides a simple, effective way for analysts to determine nitrogen (0-40 mg/L), phosphorus (0-40 mg/L), and potassium content of the soil. The Soil Fertility test kit also includes a Pocket Pal™ pH Tester for quick pH measurements: the model NPK-1 uses color disc and dip stick methods.” The kit can test for 0-60 ppm of nitrate-nitrogen in the soil, 0-130 mg/L of phosphorus, and 0-250 mg/L of potassium. For nitrate-nitrogen analysis, I used a cadmium reduction assay and performed a calcium-sulfate extraction. For phosphorus analysis, I performed a Mehlich 2 Extraction and an ascorbic acid assay. For potassium analysis, I performed a Mehlich 2 Extraction and used the Turbidimetric Tetraphenylborate method. For pH analysis, I performed an aqueous extraction and used the electrode method with a PocketPal pH tester. 7 Results/Analysis: For the analysis of my data, I ran a linear model univariate ANOVA for three different hypotheses and for each nutrient that was being tested. Each factor, site, depth and date was analyzed separately, and the interactions between each of the factors was also analyzed. My first hypothesis was that the Stetson Green contains higher nutrient concentrations than the Sandhill, which turned out to be true for nitrogen. However, the phosphorus values were not significantly higher in the Green My second hypothesis is: if the Stetson Green is over-fertilized, then it will have higher concentrations of nitrogen, phosphorus, and potassium six-inch depths (below the root zone) than at two-inch depths, compared to the Sandhill, which should not have a change in concentration depending on depth. The line graphs show how the nutrients move through the soil over time. My final, most nuanced, hypothesis indicates how nitrogen and phosphorus moves through the soil over a three-week period and the differences between the nutrient concentrations at each depth. The nitrogen levels went up in the six-inch Green samples, but the phosphorus levels went down significantly in the six-inch Green samples, which is contrary to the hypothesis. According the statistical analysis that was done on the data for nitrogen, the levels in the Stetson Green were high in Week 1, but went down to unfertilized levels in weeks two and three. For phosphorus, the levels in the Green declined in the six-inch zone over the three-week period, but increased in the two-inch zone. The ANOVA that was run for nitrogen shows statistical significance between the two sites. The ANOVA for phosphorus showed statistical significance between date and site, site and depth, and date and depth. The ANOVA ran for pH showed a statistical difference between sites and between depths. 8 Based on the ANOVA, the Stetson Green 2” and SandHill 6”, Stetson Green 6” and Stetson Green 2”, and SandHill 2” and Sandhill 6” nitrogen concentrations have statistically the same mean. Figure 1.1 Nitrogen in the Stetson Green (fertilized) and the Sandhill (unfertilized) at 2” and 6” depths. Mean +/- Standard Error. Letters represent statistical differences among categories at p<0.05. Based on the ANOVA, Stetson Green 6” and SandHill 6”, SandHill 2” and SandHill 6” had the same means, which shows that the phosphorus concentrations varied between site and depth. 9 Figure 1.2 Phosphorus in the Stetson Green (fertilized) and the Sandhill (unfertilized) at 2” and 6” depths. Mean +/- Standard Error. Letters represent statistical differences among categories at p<0.05. Figure 1.3 pH in the Stetson Green and the Sandhill at 2” and 6” depths. Mean +/- Standard Error. Letters represent statistical differences among categories at p<0.05. 10 The graph below shows that nitrogen levels over the three-week period leveled out to typical nitrogen levels in unfertilized Florida topsoil. I ran an ANOVA to test the statistical significance of the relationships between date, site, and depth. The only significant relationship was between the two sites. Figure 2.1 The graph below shows phosphorus concentrations in the soil over a three-week period. The phosphorus levels in the Green went down in the six-inch zone as they went up in the Sandhill. The ANOVA showed a statistically significant relationship between date and site, site and depth, and date and depth. 0 1 2 3 4 5 6 7 8 9 Week 1 Week 1Week 1 Week 1 Week 2 Week 2Week 2 Week 2 Week 3 Week 3Week 3 Week 3 [N] in lbs./acre[N] in lbs./acre[N] in lbs./acre[N] in lbs./acre[N] in lbs./acre[N] in lbs./acre[N] in lbs./acre[N] in lbs./acre[N] in lbs./acre[N] in lbs./acre Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Changes in N Concentrations Stetson Soils over time Stetson Soils over timeStetson Soils over time Stetson Soils over timeStetson Soils over time Stetson Soils over time Stetson Soils over time Stetson Soils over time Stetson Green 2" Stetson Green 2" Stetson Green 2"Stetson Green 2"Stetson Green 2" Stetson Green 2"Stetson Green 2"Stetson Green 2" Stetson Green 6" Stetson Green 6" Stetson Green 6"Stetson Green 6"Stetson Green 6" Stetson Green 6"Stetson Green 6"Stetson Green 6" Sandhill 2" Sandhill 2"Sandhill 2"Sandhill 2" Sandhill 2" Sandhill 6" Sandhill 6"Sandhill 6"Sandhill 6" Sandhill 6"11 Figure 2.2 There is a statistically significant difference between site and depth in pH. The only real difference seen is a generally higher pH in the Stetson Green and a higher pH in the 6” depth in both sites. Figure 2.3 0 5 10 15 20 25 30 35 40 Week 1Week 1Week 1Week 1 Week 2Week 2Week 2Week 2 Week 3Week 3Week 3Week 3 [P] in lbs./acre[P] in lbs./acre[P] in lbs./acre[P] in lbs./acre[P] in lbs./acre[P] in lbs./acre Changes in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over timeChanges in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over time Changes in P Concentrations Stetson Soils over time Stetson Green 2"Stetson Green 2"Stetson Green 2"Stetson Green 2" Stetson Green 2"Stetson Green 2"Stetson Green 2" Stetson Green 2" Stetson Green 2"Stetson Green 2"Stetson Green 2" Stetson Green 6"Stetson Green 6"Stetson Green 6"Stetson Green 6" Stetson Green 6"Stetson Green 6"Stetson Green 6" Stetson Green 6"Stetson Green 6"Stetson Green 6"Stetson Green 6"Stetson Green 6" Sandhill 2"Sandhill 2" Sandhill 2"Sandhill 2"Sandhill 2"Sandhill 2"Sandhill 2"Sandhill 2" Sandhill 6"Sandhill 6" Sandhill 6"Sandhill 6"Sandhill 6"Sandhill 6"Sandhill 6"Sandhill 6" 6 6.2 6.4 6.6 6.8 7 7.2 7.4 7.6 7.8 8 Week 1Week 1Week 1Week 1 Week 2Week 2Week 2Week 2 Week 3Week 3Week 3Week 3 pH pH in Stetson Soils over timepH in Stetson Soils over time pH in Stetson Soils over timepH in Stetson Soils over time pH in Stetson Soils over timepH in Stetson Soils over time pH in Stetson Soils over timepH in Stetson Soils over timepH in Stetson Soils over time pH in Stetson Soils over time pH in Stetson Soils over timepH in Stetson Soils over time pH in Stetson Soils over time pH in Stetson Soils over time pH in Stetson Soils over time Stetson Green 2"Stetson Green 2"Stetson Green 2"Stetson Green 2" Stetson Green 2"Stetson Green 2"Stetson Green 2" Stetson Green 2" Stetson Green 2"Stetson Green 2"Stetson Green 2" Stetson Green 6"Stetson Green 6"Stetson Green 6"Stetson Green 6" Stetson Green 6"Stetson Green 6"Stetson Green 6" Stetson Green 6" Stetson Green 6"Stetson Green 6"Stetson Green 6" Sandhill 2"Sandhill 2" Sandhill 2"Sandhill 2"Sandhill 2"Sandhill 2"Sandhill 2"Sandhill 2" Sandhill 6"Sandhill 6" Sandhill 6"Sandhill 6"Sandhill 6"Sandhill 6"Sandhill 6"Sandhill 6"12 Conclusions and Discussion: The nitrogen concentrations only varied between sites, not depth or date and the phosphorus concentrations in the Green were lower in the third week and decreased over time in the six-inch zone. Therefore, our study did not suggest that nutrients are leaching deeper into the soil horizon. The nitrogen and phosphorus levels were higher in the Green than in the Sandhill, which supported my first hypothesis, and could potentially show issues in our water, but we are not near any surface waters, which means that any high amounts of nutrients will not necessarily contaminate our local waters, unless the nutrients runoff into storm-water drains. The pH was high in the Stetson Green 6” sample, which could limit phosphorus uptake and increase the likelihood of nutrient runoff. Nitrogen and phosphorus are limiting nutrients for growth and can be detrimental to the health of waterbodies and the fish and other living organisms in the ecosystem if found in large amounts from agricultural, storm water, and wastewater runoff or other sources such as atmospheric deposition. According to the data for the different depth and sites, the nutrients in Stetson’s lawns do not seem to be in amounts that are detrimental to our water sources, however, the sample size was small and more samples in the future, perhaps considering the nutrients coming from the use of reclaimed water, would be beneficial to the larger goal of becoming a more environmentally-conscious campus. Using native plants and allowing plants to grow naturally is a way that we are already conscious of the impacts of fertilizer use, and Stetson’s Grounds staff is already finding ways to use organic herbicides and other ways to cut down on our harm to the environment. I lead this experiment with Dr. Anderson to find out more of what we are putting in our soils and whether our staff is putting levels of nitrogen and phosphorus in the soil that are unnecessary for growth. Florida’s soils are already rich with phosphorus (as can be seen in the six-inch Sandhill sample), so there is no need to put phosphorus fertilizers on our lawns. The SandHill has nutrient concentrations that are sufficient for growth, which shows that added nutrients are not 13 necessary in the Green. The ANOVA and graphs all show a stabilizing amount of phosphorus over the three-week period and nitrogen that only statistically varied between the two sites, meaning the depth and date did not make a statistical difference in nitrogen concentrations. Based on the data, ANOVA analysis and graphs, Stetson does not seem to be over-fertilizing (according to our experiment of nutrient concentrations at depth over three-weeks), which was indicative of a commitment to environmental stewardship by Stetson University. One recommendation I would make to the Stetson Grounds Department would be to use a variety of native grasses that does not need a lot of irrigation or fertilization to grow so that we could prevent excessive nutrients from leaching into groundwater or polluting surface waters, which provide economic, health, recreational and less of an expense for Stetson because we wouldn’t have to pay as much for fertilizers, pesticides and irrigation that we have to pay for using a conventional lawn cover. Also, it is recommended that calcium carbonate be used in lawn management, especially in Florida, to keep the nutrients in the sandy, mobile soil and taken up by the grasses (Yang et. al. 2007). Stetson uses integrated pest management to control pests on not a timed schedule, so perhaps our campus could not fertilize and irrigate on a schedule to save money and the environment. Managing and testing the soil to use only what is necessary for growth is the best way to keep pollutants from our lawns from going into our waterways and groundwater. 14 Appendix Table 1. ANOVA Results for Nitrogen Tests of Between-Subjects Effects Dependent Variable: N Source Type III Sum of Squares df Mean Square F Sig. Corrected Model 134.972a 11 12.270 1.673 .141 Intercept 448.028 1 448.028 61.095 .000 Date 32.056 2 16.028 2.186 .134 Site 46.694 1 46.694 6.367 .019 Depth 8.028 1 8.028 1.095 .306 Date * Site 33.389 2 16.694 2.277 .124 Date * Depth 3.389 2 1.694 .231 .795 Site * Depth .694 1 .694 .095 .761 Date * Site * Depth 10.722 2 5.361 .731 .492 Error 176.000 24 7.333 Total 759.000 36 Corrected Total 310.972 35 a. R Squared = .434 (Adjusted R Squared = .175) Table 2. ANOVA Results for Phosphorus Tests of Between-Subjects Effects Dependent Variable: P Source Type III Sum of Squares df Mean Square F Sig. Corrected Model 3203.889a 11 291.263 3.591 .004 Intercept 21805.444 1 21805.444 268.834 .000 Date 384.889 2 192.444 2.373 .115 Site 152.111 1 152.111 1.875 .184 Depth 5.444 1 5.444 .067 .798 Date * Site 1019.556 2 509.778 6.285 .006 Date * Depth 624.889 2 312.444 3.852 .035 Site * Depth 961.000 1 961.000 11.848 .002 Date * Site * Depth 56.000 2 28.000 .345 .712 15 Error 1946.667 24 81.111 Total 26956.000 36 Corrected Total 5150.556 35 a. R Squared = .622 (Adjusted R Squared = .449) Table 3. ANOVA Results for pH Tests of Between-Subjects Effects Dependent Variable: pH Source Type III Sum of Squares df Mean Square F Sig. Corrected Model 3.983a 11 .362 1.460 .211 Intercept 1876.334 1 1876.334 7564.167 .000 Date .687 2 .344 1.385 .270 Site 1.323 1 1.323 5.331 .030 Depth 1.323 1 1.323 5.331 .030 Date * Site .462 2 .231 .931 .408 Date * Depth .082 2 .041 .165 .849 Site * Depth .063 1 .063 .252 .620 Date * Site * Depth .045 2 .023 .091 .914 Error 5.953 24 .248 Total 1886.270 36 Corrected Total 9.936 35 a. R Squared = .401 (Adjusted R Squared = .126) 16 Works Cited: Anonymous. 2016. The Sources and Solutions: Agriculture. United States Environmental Protection Agency. https://www.epa.gov/nutrientpollution/sources-and-solutions-agriculture Accessed April 29, 2017. Anonymous. Soil Phosphorus: Soil Quality Kit-Guide for Educators. United States Department of Agriculture Natural Resources Conservation Service. https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_053254.pdf Accessed May 2, 2017. Beegle, D. B., W. J. Gburek, P. J. A. Kleinman, P. A. Moore Jr., G. Mullins, A. N. Sharpley, and J. 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