Increasing student attentiveness and engagement in growing Mechanized Systems Management courses

Background Growing enrollment in undergraduate MSYM courses has carried increased class sizes and then made it more difficult for students to remain attentive and engaged during lecture. In fall 2014, I maintained a dynamic lecturing style in MSYM 354, Soil Conservation and Watershed Management. Readiness tests, an active learning tool, continued to be helpful, but the mode of delivery was still largely a traditional lecture. Team based learning was utilized which divided the class into diverse learning teams for both the lab and the lecture. Students completed readiness tests both individually and in their teams. The objective of this activity was to solicit more student attentiveness and engagement in the fall of 2015 by improving the mode of delivery. Improvements I implemented three improvements to my lecture style in fall of 2015 in MSYM 452, Irrigation Systems Management. With Dr. Eisenhauer’s retirement, I had agreed to teach MSYM 452 instead of MSYM 354. First, a more effective use of readiness tests to stimulate discussion and introduce lecture topics was utilized. Instead of going over readiness test answers quickly, I took 5-20 minutes to discuss the answers while the students were curious about the correct answers. Also, I used one or two of the readiness test questions as a transition to introduce the new lecture topic. Sometimes there was a shuffle in the classroom when students realized I had went over all five questions and they began to relax for the regular lecture material, indicating increased engagement during this time immediately after a readiness test. Second, I used more in-class example problems. These required students to work in their teams to quantitatively apply the concepts they learned in lecture. Example problems were scheduled for the middle of the lecture period when student attentiveness can start to wane. Finally, I increased the use of the white board and decreased the use of PowerPoint. This forced me to slow down (which is hard when I am excited about the material) and be more interactive with the students. I can better read students’ faces and body language, and then adjust my lecture accordingly. A good textbook in MSYM 452 helped make this transition possible, since I did not need to rely on PowerPoint to disseminate detailed lecture material

Modeling Vadose Zone Hydrology: Lecture Notes

Modeling Vadose Zone Hydrology is a graduate-level course offered biennially in the Department of Biological Systems Engineering. Topics included hydraulic properties of porous media, application of Darcy\u27s Law in variably saturated media, hydrologic and transport processes in the vadose zone, and solution of steady and unsteady flow problems using numerical techniques. A graphical approach for characterizing vertical one-dimensional problems with energy head profiles was emphasized. Common one-dimensional flow and transport problems were solved analytically. The course was taught using a combination of lecture notes and PowerPoint presentations. The lecture notes from 2021, captured using the Microsoft Whiteboard app with a Microsoft Surface, are presented here. The lecture notes are open access (CC BY-NC 4.0) and may be useful to other instructors in vadose zone hydrology or soil physics

Peer Review of Teaching: ET Theory, Deficit Irrigation and Consumptive Use

A BSE Peer Review of Teaching was carried out for a graduate level course on Advanced Irrigation Management. This course has been offered for several years; each time improvements are made, but there is always a need for additional improvement. In particular, ET theory, deficit irrigation, and consumptive use are topics that the students struggle to grasp. These topics involve a relatively high level of math for an MS-level (800-level) Agricultural Systems Technology course, and the available materials on these topics either were not well developed or were not a good fit for this class. The primary objective was to develop clear lecture materials, readiness test questions, homework problems, and exam questions on these particular topics. Results from Post-Pre Survey indicated a large increase in the students’ self-assessed skills (related to learning objectives) during the semester. Future course improvements should include updating the course sequence of topics to provide a more uniform distribution of workload for the students

Preferential flow in riparian buffers: Current research and future needs.

Preferential flow in riparian buffers can substantially compromise their effectiveness in reducing contaminants from overland runoff. The objective of this article is to introduce a collection of five articles on current research into subsurface preferential flow measurement, visualization, modeling, and impacts on contaminant fate and transport at scales ranging from the subsurface pore scale to the plot scale to the watershed scale. This collection presents selected works from a broader invited session on “Preferential flow and piping in riparian buffers” at the 2020 ASABE Annual International Meeting. Major findings include: new methodologies, such as light transmission and geophysics, to characterize subsurface preferential flow; an infiltration partitioning approach to quantify preferential flow from field experiments; a kinematic dispersive wave model to effectively simulate subsurface preferential flow; and the significant impact of surface concentrated flow pathways on pesticide fate and transport both upstream and within a riparian buffer. Future work is needed to develop methods and tools to identify PF areas and management solutions within a landscape, and to update both research and design models to better quantify and account for PF processes

Evaluating evapotranspiration Values in Rwanda while Using the Turc and Hargreaves-Samani Equations.

Evapotranspiration (ET) is an important component of the hydrologic cycle and involves the exchange of water between the surrounding water bodies, soil, crop surfaces, and the atmosphere. Crop growth and yields are largely affected by the rate of ET, especially in semi-arid areas where the rate of ET is high and rainfall is not sufficient and reliable to add more water into the soil for crop use. Solar radiation, relative humidity, air temperature, rainfall, and wind velocity are some of the meteorological factors that affect ET. Therefore, this research was aimed at determining ET and its trend across Rwanda using climatic data measured at 5 sites. With the research, we accessed meteorology data measured at synaptic stations in the five provinces of Rwanda (Kigali city/central, Kawangire/Eastern, Ruberengera/Western, Ruhengeri/Northern and Gikongoro/ and used the data to calculate reference evapotranspiration (ET) for the recent 10 years (2010-2018). Equations were used to calculate extra-terrestrial radiations, solar radiations, evapotranspiration using the FAO-56 guidelines - Turc method (1961) and Hargreaves-Samani (HS) method (1983). The obtained data was analyzed using the two methods and graph were plotted for visualization. Both methods have performed well in semi-humid and semi-arid environmental conditions. The average monthly reference evapotranspiration for both equations ranges from 3 to 5 mm/day. The Hu-Ts graphs for all the five locations shows a low value of reference ET (3 to 4 mm/day) for the year of 2018 compared to the previous years. Generally, there was consistency in variation in the reference ET throughout the 10 years for both the equations. The Turc method underestimates reference ET value compared to the HS method. The difference and variation of reference crop evapotranspiration for both the equations might have been due to the different locations since they have variations in climatic conditions that contributes a lot to the evapotranspiration value in the region

Evaluation of a hybrid remote sensing evapotranspiration model for variable rate irrigation management

Accurate generation of spatial irrigation prescriptions is essential for implementation and evaluation of variable rate irrigation (VRI) technology. A hybrid remote sensing evapotranspiration (ET) model was evaluated for use in developing irrigation prescriptions for a VRI center pivot. The model is a combination of a two-source energy balance model and a reflectance based crop coefficient water balance model. Spatial ET and soil water depletion were modeled for a 10 km2 area consisting of rainfed and irrigated maize fields in eastern Nebraska for 2013. Multispectral images from Landsat 8 Operational Land Imager and Thermal Infrared Sensor were used as model input. Modeled net radiation and soil heat fluxes compared well with measurements from eddy covariance systems located within three fields in the study area. Modeled sensible heat flux did not compare well. Latent heat flux compared well for the only mid-summer image, but poorly for the one spring and two fall images. The water balance ET compared well with the two-source energy balance ET for irrigated maize, but not for dryland maize. Image frequency is thought to be a contributing factor in the poor performance of the water balance. In 2015 the hybrid model will be used to generate irrigation prescription maps for a VRI system located in the study area based on modeled soil moisture depletion. Future research will focus on model parameterization and utilize aerial imagery and satellite imagery from other sensors for improved image frequency. Note: this is a revision of the original paper correcting erroneous data where one of the flux sites was mistakenly analyzed as soybeans, when it was actually maize. Mean biased error signs have also been corrected

Evaluation of the bank stability and toe erosion model (BSTEM) for predicting lateral retreat on composite streambanks

Streambank erosion is known to be a major source of sediment in streams and rivers. The Bank Stability and Toe Erosion Model (BSTEM) was developed in order to predict streambank retreat due to both fluvial erosion and geotechnical failure. However, few, if any, model evaluations using long-term streambank retreat data have been performed. The objectives of this research were to (1) monitor long-term composite streambank retreat during a hydraulically active period on a rapidly migrating stream, (2) evaluate BSTEM’s ability to predict the measured streambank retreat, and (3) assess the importance of accurate geotechnical, fluvial erosion, and near-bank pore-water pressure properties. The Barren Fork Creek in northeastern Oklahoma laterally eroded 7.8 to 20.9 m along a 100-m length of stream between April and October 2009 based on regular bank location surveys. The most significant lateral retreat occurred in mid- to late-May and September due to a series of storm events, and not necessarily the most extreme events observed during the monitoring period. BSTEM (version 5.2) was not originally programmed to run multiple hydrographs iteratively, so a subroutine was written that automatically input the temporal sequence of stream stage and to lag the water table in the near-bank ground water depending on user settings. Eight BSTEM simulations of the Barren Fork Creek streambank were performed using combinations of the following input data: with and without a water table lag; default BSTEM geotechnical parameters (moderate silt loam) versus laboratory measured geotechnical parameters based on direct shear tests on saturated soil samples; and default BSTEM fluvial erosion parameters versus field measured fluvial erosion parameters from submerged jet tests. Using default BSTEM input values underestimated the actual erosion that occurred. Lagging the water table predicted more geotechnical failures resulting in greater streambank retreat. Using measured fluvial and geotechnical parameters and a water table lag also under predicted retreat (approximately 3.3 m), but did predict the appropriate timing of streambank collapses. The under prediction of retreat was hypothesized to be due to over predicting the critical shear stress of the non-cohesive gravel, under predicting the erodibility of the non-cohesive gravel, and/or under predicting the imposed shear stress acting on the streambank. Current research improving our understanding of shear stress distributions, streambank pore-water pressure dynamics, and methods for estimating excess shear stress parameters for noncohesive soils will be critical for improving BSTEM and other streambank stability models

Evaluation of the bank stability and toe erosion model (BSTEM) for predicting lateral retreat on composite streambanks

Streambank erosion is known to be a major source of sediment in streams and rivers. The Bank Stability and Toe Erosion Model (BSTEM) was developed in order to predict streambank retreat due to both fluvial erosion and geotechnical failure. However, few, if any, model evaluations using long-term streambank retreat data have been performed. The objectives of this research were to (1) monitor long-term composite streambank retreat during a hydraulically active period on a rapidly migrating stream, (2) evaluate BSTEM’s ability to predict the measured streambank retreat, and (3) assess the importance of accurate geotechnical, fluvial erosion, and near-bank pore-water pressure properties. The Barren Fork Creek in northeastern Oklahoma laterally eroded 7.8 to 20.9 m along a 100-m length of stream between April and October 2009 based on regular bank location surveys. The most significant lateral retreat occurred in mid- to late-May and September due to a series of storm events, and not necessarily the most extreme events observed during the monitoring period. BSTEM (version 5.2) was not originally programmed to run multiple hydrographs iteratively, so a subroutine was written that automatically input the temporal sequence of stream stage and to lag the water table in the near-bank ground water depending on user settings. Eight BSTEM simulations of the Barren Fork Creek streambank were performed using combinations of the following input data: with and without a water table lag; default BSTEM geotechnical parameters (moderate silt loam) versus laboratory measured geotechnical parameters based on direct shear tests on saturated soil samples; and default BSTEM fluvial erosion parameters versus field measured fluvial erosion parameters from submerged jet tests. Using default BSTEM input values underestimated the actual erosion that occurred. Lagging the water table predicted more geotechnical failures resulting in greater streambank retreat. Using measured fluvial and geotechnical parameters and a water table lag also under predicted retreat (approximately 3.3 m), but did predict the appropriate timing of streambank collapses. The under prediction of retreat was hypothesized to be due to over predicting the critical shear stress of the non-cohesive gravel, under predicting the erodibility of the non-cohesive gravel, and/or under predicting the imposed shear stress acting on the streambank. Current research improving our understanding of shear stress distributions, streambank pore-water pressure dynamics, and methods for estimating excess shear stress parameters for noncohesive soils will be critical for improving BSTEM and other streambank stability models

Effect of Limited Water Supplies on Center Pivot Performance

When appropriately designed and operated, center pivot irrigation systems can efficiently irrigate many crops grown on diverse soil and terrain conditions. However, a significant number of pivots are not supplied with an adequate water to operate as envisioned. We simulated the hydraulics of a center pivot irrigation system, including the pump curve, flow rate, pipeline hydraulics, pressure regulators, nozzle flow rate, and irrigation application uniformity. This was used to analyse the performance of a center pivot for a sloping field for both adequate and inadequate water flow rate. The performance was simulated for a range of inlet pressures when pressure regulators were used and for systems without pressure regulators. Inadequate inflow causes major degradation of the uniformity of water application and the ability of the system to meet crop needs. Results show that regulators improve uniformity for high-flow conditions but do not improve the discharge uniformity when inlet pressures—and therefore system inflow—drop below design specifications. The variability of discharge at the distal end of the pivot is less for unregulated conditions than when regulators are used for limited inflows

Capturing Spatial Variability in Maize and Soybean using Stationary Sensor Nodes

• Irrigation in agriculture maximizes crop yield and improves food security globally • Irrigation scheduling is strongly based on the ability to accurately estimate the appropriate amount and timing of water application • The timing of the irrigation can best be informed through the crop canopy stress, and the amount of irrigation is informed through soil moisture depletion • Developing upper (non-water stressed) and lower (non-transpiring) baselines for irrigated and non-irrigated maize and soybean • Investigating the relationship between the canopy stress and the soil moisture stress The canopy temperature stress and soil moisture depletion had stronger correlation for non-irrigated treatments in soybean than maiz