The first two chapters of this dissertation were conducted to help develop improved laboratory protocols on soil health assessment for soil respiration and aggregate stability analyses. Bulk soil samples were collected across different locations in Oklahoma (U.S.A.). These samples were collected to a depth of 10 cm representing a wide range of soil physical and chemical properties from different land uses. The soil respiration study was performed to improve understanding of the effect of chamber volume-to-soil mass ratio factor on the measured CO₂-C. The aggregate stability study was conducted to evaluate the possibility of using aggregate samples recovered from oven-dried soil samples as processed through different mechanical grinders. Results of these two studies enabled the development of improved methods that were less labor intensive, higher sample throughput, wider dynamic test range, and a greater potential for further automation. Furthermore, the identified improved methods also have low coefficient of variation demonstrating measurement precision and high correlation with the commonly used methods. The last chapter of this dissertation was conducted to gain insights on student’s perception on how the virtual laboratory enhanced their understanding and appreciation of important soil science concepts, identify challenges and benefits, and determine its effectiveness as possible alternate to hands-on laboratory in the future. This virtual laboratory was developed during the outbreak of the novel coronavirus pandemic. A series of video clips were prepared and combined to produce a composite instructional video, one for each laboratory exercise. These videos were then made available online for student access. A survey instrument was used to gather data from students. Student feedback revealed that the virtual laboratory sessions has successfully enhanced their understanding and appreciation of important soil science concepts. Step-by-step explanation of activities and the flexibility that it provides were identified as key positive attributes. Conversely, the absence of hands-on experience, instructors to address questions, and interaction with fellow classmates were identified as the top challenges with virtual labs. These results indicate that students still favor active in-person learning over that of virtual laboratory delivery despite the latter’s effectiveness in achieving learning.
Glenn Arthur A. Garcia (Wed,) studied this question.