Soil health assessment of the Sanborn Field long-term experimental study

Field of study: Natural resources.Drs. Randall J. Miles and Stephen H. Anderson, Dissertation Supervisors.Includes vita."May 2018."Soil health assessment uses a combination of potential indicators affecting soil processes to comprehensively monitor soil change, caused by cropping systems and soil management. The objectives of the study were to assess the effects of selected cropping systems, soil management and landscape slope positions on the soil health characteristics of the Sanborn Field long-term experimental study in Columbia, Missouri, United States. Soil samples were collected on each of four dates over two years (8 th May 2014, 4th September 2014, 1st April 2016, and 18th August 2016) from selected plots to address each objective, and these time samples were used as replications. Soil physical, chemical, and biological characteristics were analyzed in the laboratory for these samples to assess soil health using the Cornell Comprehensive Assessment of Soil Health (CASH) method. To assess soil health in this study, soil health scoring was determined used R-studio version 1.1.149 to relate the interaction of cropping systems, soil management, and slope positions. Most soil resources on Sanborn Field are a poorly-drained claypan soil classified as a Mexico silt loam (fine, smectitic, mesic Vertic Epiaqualf). In addition, soil samples collected from Tucker Prairie was used as a proxy for the original state of Sanborn Field soils. The first study was conducted to evaluate the effects of long-term cropping systems on soil health properties. The results from the characterization indicated that continuous timothy (Phleum pretense L.) and warm season grass treatments were classified with very high soil health scores, and the lowest score was found for continuous corn (Zea mays L.). In addition, results showed strong positive linear associations between soil organic carbon, total nitrogen, potentially mineralizable nitrogen, active carbon, microbial biomass, and water stable aggregates; while a strong negative linear correlation existed between each of these properties and bulk density. The second study was conducted to evaluate the effects of long-term annual applications of no fertilizer, full fertilizer, and manure on soil health measurements of selected cropping systems. Different cropping systems, including continuous corn, continuous wheat (Triticum aestivum L.), corn-wheat-red clover (Trifolium pretense L.) rotation, and corn-soybean (Glycine max L.)-wheat rotation treatments were used in this study. Results showed that annual dairy cow (Bos Taurus) manure applications had the greatest effect on all soil health indicators and had the largest overall soil health score compared to full fertility and no fertilizer treatments. Moreover, continuous wheat with manure application presented the best combination of effects on soil properties with the largest score for most soil health indicators and an overall health score of 82 out of 100 classified as very high which is the best. The last study evaluated the effects of landscape slope positions on soil health properties of the long-term experiment. Results showed that the summit position had the highest overall soil health score while the lowest score was found on the shoulder position. However, there were no significant differences along the transect slope for water-stable aggregates and bulk density. There were significant differences along the transect for the biological properties such as soil organic carbon, active carbon, potentially mineralizable nitrogen, and microbial biomass. Results of this study illustrate the effect of selected variables on soil health and provide the recent addition of using biological characteristics to account for soil health properties. It is important to remember that this study of the long-term Sanborn Field experiment is just for a small-sized plot area. Future studies of soil management effects on soil health need to account for their own field conditions and their own unique environment.Includes bibliographical references

Essential oils from the Malaysian Citrus (Rutaceae) plants

This review article appraises the extraction methods, compositions, and bioactivities of the essential oils from the Citrus species (family: Rutaceae) endemic to Malaysia including C. aurantifolia, C. grandis, C. hystrix, and C. microcarpa. Generally, the fresh peels and leaves of the Citrus species were extracted using different methods such as steam and water distillation, Likens-Nikerson extraction, solvent extraction, and headspace solid-phase micro-extraction (HS-SPME). Most of the Citrus oils were found to be rich in monoterpene hydrocarbons with limonene (1) as the major component identified in the peels of C. aurantifolia (39.3%), C. grandis (81.6%–96.9%), and C. microcarpa (94.0%), while sabinene (19) was the major component in the peels of C. hystrix (36.4%–48.5%). In addition, citronellal (20) (61.7%–72.5%), linalool (18) (56.5%), and hedycaryol (23) (19.0%) were identified as the major components in the oil of C. hystrix leaves, C. grandis blossom and C. microcarpa leaves, respectively. The C. hystrix essential oil has been experimentally shown to have antimicrobial and antifeedant activities, while no bioactivity study has been reported on the essential oils of other Malaysian Citrus species

วิธีวิเคราะห์ปริมาณกรดเบนโซอิกและการประยุกต์ใช้ Analytical Methods for Determination of Benzoic Acid and Their Applications

บทคัดย่อ วัตถุประสงค์: เพื่อพัฒนาและตรวจสอบวิธีวิเคราะห์ปริมาณกรดเบนโซอิกในผลิตภัณฑ์อาหาร วิธีการศึกษา: พัฒนาวิธีวิเคราะห์ด้วยการปรับค่าต่าง ๆ และสภาวะของระบบในแต่ละวิธีให้เหมาะสม ตรวจสอบทุกวิธีวิเคราะห์ และทดสอบวิเคราะห์ปริมาณกรดเบนโซอิกในอาหาร ผลการศึกษา: การวิเคราะห์ด้วยวิธีโครมาโทกราฟีเหลวสมรรถนะสูงใช้คอลัมน์ C18 เป็นวัฏภาคนิ่ง วัฏภาคเคลื่อนที่ประกอบด้วยแอมโมเนียม อะซิเตตบัฟเฟอร์ และเมทานอล ตรวจวัดที่ความยาวคลื่น 235 นาโนเมตร ช่วงความเป็นเส้นตรงของกราฟมาตรฐานที่ใช้ในการศึกษานี้ คือ 7.8 – 500 µg/ml (r2 > 0.999) ค่าขีดจำกัดการตรวจหา (limit of detection; LOD) และค่าขีดจำกัดการวิเคราะห์เชิงปริมาณ (limit of quantitation; LOQ) เท่ากับ 2.5 และ 3.8 ng/ml ตามลำดับ การวิเคราะห์ด้วยอัตราไวโอเลตและวิสิเบิลสเปกโทรสโกปี วัดค่าการดูดกลืนแสงที่ความยาวคลื่น 240 นาโนเมตร ช่วงความเป็นเส้นตรงของกราฟมาตรฐานคือ 3 – 150 µg/ml (r2 > 0.999) ค่า LOD และ LOQ เท่ากับ 14.2 และ 43.1 ng/ml ตามลำดับ การวิเคราะห์ด้วยวิธีการไตเตรทใช้สารละลายโซเดียมไฮดรอกไซด์ที่ทราบความเข้มข้นแน่นอนและใช้ฟีนอล์ฟทาลีนเป็นอินดิเคเตอร์ ช่วงความเป็นเส้นตรงของกราฟมาตรฐาน คือ 25 – 500 µg/ml (r2 > 0.999) ค่า LOD และ LOQ เท่ากับ 6.0 และ 25.0 µg/ml ตามลำดับ ตรวจสอบกรดเบนโซอิกโดยใช้สารละลายเฟอริกคลอไรด์ 2% และคอปเปอร์ซัลเฟต 5% ได้สารประกอบในรูปตะกอนสีส้มและสีฟ้าตามลำดับ น้ำยาทั้งสองชนิดสามารถตรวจสอบกรดเบนโซอิกได้ที่ความเข้มข้นตั้งแต่ 500 µg/ml ขึ้นไป วิธี 4 วิธีนี้สามารถตรวจพบปริมาณกรดเบนโซอิกในตัวอย่างอาหาร เครื่องดื่มผสมถังเช่าและเส้นขนมจีนสดอยู่ในระดับที่ยอมรับได้เมื่ออ้างอิงจากประกาศของสำนักงานคณะกรรมการอาหารและยาของประเทศไทย สรุปผลการศึกษา: โครมาโตกราฟีเหลวสมรรถนะสูง อัตราไวโอเลตและวิสิเบิลสเปกโทรสโกปี การไตเตรท การตรวจสอบด้วยปฏิกิริยาการตกตะกอนโดยใช้สารละลายเฟอริกคลอไรด์และคอปเปอร์ซัลเฟต ที่ได้รับการพัฒนาและทดสอบ สามารถนำมาประยุกต์ใช้ในการวิเคราะห์กรดเบนโซอิกในตัวอย่างอาหารและเครื่องดื่มได้ คำสำคัญ: กรดเบนโซอิก, โครมาโทกราฟีเหลวสมรรถนะสูง, อัตราไวโอเลตและวิสิเบิลสเปกโทรสโกปี, ไตเตรท,  เฟอริกคลอไรด์, คอปเปอร์ซัลเฟตAbstract Objectiv:O To develop and validate the analytical methods for the determination of benzoic acid in foodstuffs. Methods: The system configurations and conditions of the methods were optimized. Method validations were performed for all analytical methods. The methods were then applied for the quantitative analyses of benzoic acid in foodstuffs. Results: HPLC system was developed using C18 column as a stationary phase with ammonium acetate buffer and methanol as a mobile phase. Detection wavelength of 235 nm was used. The linear range was 7.8 - 500 µg/mL (r2 > 0.999). Limit of detection (LOD) and limit of quantitation (LOQ) were 2.5 and 3.8 ng/mL, respectively. For UV-visible spectrophotometric method, the optimum wavelength was observed at 240 nm, the linear range was 3 - 150 µg/mL (r2 > 0.999). LOD and LOQ were 14.2 and 43.1 ng/mL, respectively. Acid-base titration technique was performed using an exact concentration of standard sodium hydroxide solution as a titrant and phenolphthalein T.S. as an indicator. The linear range of the method was 25 - 500 µg/mL (r2 > 0.999). LOD and LOQ were 6.0 and 25.0 µg/mL, respectively. Precipitation methods using 2% ferric chloride and 5% copper (II) sulfate solution were developed and yielded beige-tan and blue precipitate of metal-aromatic acid complex, respectively. Both methods could detect benzoic acid at the concentration of higher than 500 µg/mL. These methods were applied to determine benzoic acid in foodstuffs (cordyceps herbal drink and fresh rice noodle). Acceptable ranges of benzoic acid according to Thai FDA regulation were found. Conclusion: HPLC, UV-visible spectrophotometry, titration, ferric chloride test and copper sulfate test were developed and validated. All methods were successfully applied to determine benzoic acid in food and beverage. Keywords benzoic acid, HPLC, UV-vis spectrophotometry, titration, ferric chloride, copper sulfate

Detection of Opisthorchis viverrini Infection among the ASEAN Population in Thailand Using a Verbal Screening Test and Fecal Concentrator Kit

Background: Opisthorchis viverrini is a serious health problem in Southeast Asia. The infection is associated with cholangiocarcinoma. Therefore, this study was aimed to detect O. viverrini infections among the ASEAN population in Thailand. Methods: A cross-sectional study was conducted among 249 individuals from ASEAN populations in Thailand including Thai, Laotian, Cambodian, and Myanmar. Participants were screened using the O. viverrini verbal screening test (OvVST). Fecal samples were processed by the mini-parasep sf parasite fecal concentrator. Results: The infection rate of O. viverrini was 27.21%. The majority of infections was detected in females, in the age group 31-40 yr old, in the primary school education level, and in the occupation of labor. By country, O. viverrini infection was detected more often in the Lao PDR (30.77%). In screening for O. viverrini infection, OvVST had a high sensitivity (93.48%), specificity (86.70%), NPV (98.32%), and accuracy (87.95%). The PPV was 61.43% for OvVTS. The observed agreement was substantial for OvVST (k-value = 0.64). Conclusion: O. viverrini infections are still detected in ASEAN countries therefore large scale active surveillance is required. OvVST had a high sensitivity, specificity, and accuracy for screening the risk groups for O. viverrini

Soil Health Assessment of the Sanborn Field Long-term Experimental Study

Soil health assessment uses a combination of potential indicators affecting soil processes to comprehensively monitor soil change, caused by cropping systems and soil management. The objectives of the study were to assess the effects of selected cropping systems, soil management and landscape slope positions on the soil health characteristics of the Sanborn Field long-term experimental study in Columbia, Missouri, United States. Soil samples were collected on each of four dates over two years (8th May 2014, 4th September 2014, 1st April 2016, and 18 th August 2016) from selected plots to address each objective, and these time samples were used as replications. Soil physical, chemical, and biological characteristics were analyzed in the laboratory for these samples to assess soil health using the Cornell Comprehensive Assessment of Soil Health (CASH) method. To assess soil health in this study, soil health scoring was determined used R-studio version 1.1.149 to relate the interaction of cropping systems, soil management, and slope positions. Most soil resources on Sanborn Field are a poorly-drained claypan soil classified as a Mexico silt loam (fine, smectitic, mesic Vertic Epiaqualf). In addition, soil samples collected from Tucker Prairie was used as a proxy for the original state of Sanborn Field soils. The first study was conducted to evaluate the effects of long-term cropping systems on soil health properties. The results from the characterization indicated that continuous timothy (Phleum pretense L.) and warm season grass treatments were classified with very high soil health scores, and the lowest score was found for continuous corn (Zea mays L.). In addition, results showed strong positive linear associations between soil organic carbon, total nitrogen, potentially mineralizable nitrogen, active carbon, microbial biomass, and water stable aggregates; while a strong negative linear correlation existed between each of these properties and bulk density. The second study was conducted to evaluate the effects of long-term annual applications of no fertilizer, full fertilizer, and manure on soil health measurements of selected cropping systems. Different cropping systems, including continuous corn, continuous wheat (Triticum aestivum L.), corn-wheat-red clover (Trifolium pretense L.) rotation, and corn-soybean (Glycine max L.)-wheat rotation treatments were used in this study. Results showed that annual dairy cow (Bos Taurus ) manure applications had the greatest effect on all soil health indicators and had the largest overall soil health score compared to full fertility and no fertilizer treatments. Moreover, continuous wheat with manure application presented the best combination of effects on soil properties with the largest score for most soil health indicators and an overall health score of 82 out of 100 classified as very high which is the best. The last study evaluated the effects of landscape slope positions on soil health properties of the long-term experiment. Results showed that the summit position had the highest overall soil health score while the lowest score was found on the shoulder position. However, there were no significant differences along the transect slope for water-stable aggregates and bulk density. There were significant differences along the transect for the biological properties such as soil organic carbon, active carbon, potentially mineralizable nitrogen, and microbial biomass. Results of this study illustrate the effect of selected variables on soil health and provide the recent addition of using biological characteristics to account for soil health properties. It is important to remember that this study of the long-term Sanborn Field experiment is just for a small-sized plot area. Future studies of soil management effects on soil health need to account for their own field conditions and their own unique environment

Estimating Occupational Exposure to VOCs, SVOCs, Particles and Participant Survey Reported Symptoms in Central Thailand Rice Farmers Using Multiple Sampling Techniques

Thailand is known for its agricultural productivity and rice exportation. Most farms use small machines and manual labor, creating potential exposure to multiple health hazards. A cross-sectional study was conducted to measure pollutants liberated during preparation, pesticide application, and harvesting. Thirty rice farmers, mostly males from 41 to 50 years old, participated. The participant survey data showed that 53.3% of the respondents spent >2 h per crop on preparation, <1 h on pesticide application, and about 1–2 h harvesting; 86.7% of the respondents maintained and stored mechanical applicators at home, suggesting possible after-work exposures. Gloves, fabric masks, boots, and hats were worn during all activities, and >90% wore long sleeved shirts and pants. VOCs and SVOCs were collected using charcoal tubes and solid phase micro sample extraction (SPME). An analysis of the charcoal and SPME samplers found that 30 compounds were detected overall and that 10 were in both the charcoal tubes and SPME samplers. The chemicals most often detected were 1, 1, 1 Trichloro ethane and xylene. Additionally, farmers experienced the highest exposure to particulates during harvesting. These results demonstrated that farmers experience multiple exposures while farming and that risk communication with education or training programs may mitigate exposure

Efficacy of treating bacterial bioaerosols with weakly acidic hypochlorous water: A simulation chamber study

The COVID-19 pandemic highlighted the dangers of airborne transmission and the risks of pathogen-containing small airborne droplet inhalation as an infection route. As a pathogen control, Weakly Acidic Hypochlorous Water (WAHW) is used for surface disinfection. However, there are limited assessments of air disinfection by WAHW against airborne pathogens like bioaerosols. This was an empirical study evaluating the disinfection efficacy of WAHW in an atmospheric simulation chamber system against four selected model bacteria. The strains tested included Staphylococcus aureus (SA), Escherichia coli (EC), Pseudomonas aeruginosa (PA), and Pseudomonas aeruginosa (PAO1). Each bacterial solution was nebulized into the chamber system as the initial step, and bioaerosol was collected into the liquid medium by a bio-sampler for colony forming units (CFU) determination. Secondly, the nebulized bacterial bioaerosol was exposed to nebulized double distilled water (DDW) as the control and nebulized 150 ppm of WAHW as the experimental groups. After the 3 and 30-min reaction periods, the aerosol mixture inside the chamber was sampled in liquid media and then cultured on agar plates with different dilution factors to determine the CFU. Survival rates were calculated by a pre-exposed CFU value as a reference point. The use of WAHW decreased bacterial survival rates to 1.65–30.15% compared to the DDW control. PAO1 showed the highest survival rates and stability at 3 min was higher than 30 min in all experiments. Statistical analysis indicated that bacteria survival rates were significantly reduced compared to the controls. This work verifies the bactericidal effects against Gram-positive/negative bioaerosols of WAHW treatment. As WAHW contains chlorine in the acid solution, residual chlorine air concentration is a concern and the disinfection effect at different concentrations also requires investigation. Future studies should identify optimal times to minimize the treated time range and require measurements in a real environment

Isolation of Cryptococcus gattii from a Castanopsis argyrophylla tree hollow (Mai-Kaw), Chiang Mai, Thailand

The pathogenic yeast Cryptococcus gattii was isolated from a tree hollow of a Castanopsis argyrophylla King ex Hook.f. (Fagaceae) in Chiang Mai, Thailand. Molecular characterization with amplified fragment length polymorphism analysis and multi-locus sequence typing showed that this isolate belonged to genotype AFLP4/VGI representing C. gattii sensu stricto. Subsequent comparison of the environmental isolate with those from clinical samples from Thailand showed that they grouped closely together in a single cluster