Effects of High Ammonium/Nitrate Ratios on Nitrification and Growth of Wheat in Hydroponics

Nitrogen is the only plant nutrient taken up as both a cation (NH4 +) and anion (NO3-). Nitrate is considered the safe form of N and NH/ is generally thought to be toxic, especially at high levels. High NH/ /NO3- ratios are thought to be toxic because they result in a rhizosphere pH low enough to damage root membranes, induced cation deficiencies, and build-up of NH3 caused by delayed NH/ assimilation. These factors can be minimized in hydroponic culture. The objective of these studies was to quantify the effects of high NH4 + IN 0 3- ratios on nitrification and growth of wheat in hydroponics. Two cultivars of wheat (Triticum aestivum L.) were grown to maturity with either 15% or 80% of the N supplied as NH4+. The effect of using CL- versus so/- as counter ions to NH4 + was also examined. Yield was not significantly affected by NH4 + ratio or counter ion. Seed protein was increased from 15 to 19% with high NH4 +. Harvest index was reduced from 52 to 48% with 80% NH4 +, but was unaffected by counter ion. Rates of nitrification in hydroponic culture are not well quantified and could result in significant conversion of NH4+ to NO3- before plant uptake. An isotopic dilution study was conducted to quantify rates of nitrification in hydroponic culture. A 2 x 2 x 2 factorial design was used to examine the effect of pH (5.8 or 7.0), inoculation with nitrifying bacteria, and the presence of plants. This study was done with wheat grown in vigorously-aerated, 2-L bottles. Each bottle contained 10 g of diatomaceous earth to provide surface area for microbial growth. Nitrate began to accumulate in 5 din unplanted, inoculated bottles at pH 7.0; in 20 d at pH 5.8 with inoculation; but did not begin to accumulate in non-inoculated bottles (pH 5.8 or 7.0) until day 30. Nitrate never accumulated in any of the planted bottles, most likely because plants consumed the No 3- that was produced. Calculations from the isotopic dilution measurements indicated that the rate of nitrification averaged 58 μmol No 3- L-1 d-1 in the planted bottles, and averaged 270 μmol NO3- L- 1 d-1 in unplanted bottles. Nitrification was likely reduced in the planted bottles because the reduced concentration of NH4 + limited nitrification. To provide rapid, inexpensive measurement of nutrient concentration in hydroponic solution, five colorimetric tests were evaluated. Tests for NO3- and PO4 were accurate and reliable, but the tests for SO4^2-, Si 0 2, and Fe need additional refinement

Assessing Community-Engaged Learning Impacts using Ripple Effects Mapping

Communicating Sustainability, an upper level undergraduate service-learning live broadcast course was created at Utah State University to help students gain critical skills in communicating and participating in local sustainability efforts. Community-Engaged Learning was a key component applied in gaining and using these skills. This study sought to capture the impacts of this course on both its students and the community partners who worked with those students using Ripple Effects Mapping. Key findings include: powerful impacts on student learning, growth and ability to engage in local movements; as well as clearly defined benefits for community partners. Included in this study are implications on how to apply Ripple Effects Mapping (REM) to measure impacts in other service-learning or project-based courses

Effect of Vascepa (icosapent ethyl) on progression of coronary atherosclerosis in patients with elevated triglycerides (200-499 mg/dL) on statin therapy: Rationale and design of the EVAPORATE study.

Despite reducing progression and promoting regression of coronary atherosclerosis, statin therapy does not fully address residual cardiovascular (CV) risk. High-purity eicosapentaenoic acid (EPA) added to a statin has been shown to reduce CV events and induce regression of coronary atherosclerosis in imaging studies; however, data are from Japanese populations without high triglyceride (TG) levels and baseline EPA serum levels greater than those in North American populations. Icosapent ethyl is a high-purity prescription EPA ethyl ester approved at 4 g/d as an adjunct to diet to reduce TG levels in adults with TG levels >499 mg/dL. The objective of the randomized, double-blind, placebo-controlled EVAPORATE study is to evaluate the effects of icosapent ethyl 4 g/d on atherosclerotic plaque in a North American population of statin-treated patients with coronary atherosclerosis, TG levels of 200 to 499 mg/dL, and low-density lipoprotein cholesterol levels of 40 to 115 mg/dL. The primary endpoint is change in low-attenuation plaque volume measured by multidetector computed tomography angiography. Secondary endpoints include incident plaque rates; quantitative changes in different plaque types and morphology; changes in markers of inflammation, lipids, and lipoproteins; and the relationship between these changes and plaque burden and/or plaque vulnerability. Approximately 80 patients will be followed for 9 to 18 months. The clinical implications of icosapent ethyl 4 g/d treatment added to statin therapy on CV endpoints are being evaluated in the large CV outcomes study REDUCE-IT. EVAPORATE will provide important imaging-derived data that may add relevance to the clinically derived outcomes from REDUCE-IT