Diverse activities, both natural and anthropogenic processes, notably the traffic of agricultural machinery, induce soil compaction in agricultural fields. This study quantifies the effects of vertical compaction on a sandy loam soil and its implications for the growth of canola. A John Deere 1023 E tractor equipped with ballasts traversed a field layout perpendicular to the direction of seeding. Three compaction levels were created by varying the number of tractor wheel passes. The effect on the soil properties and the performance of canola crops for each compaction level were determined in comparison to a control group (zero compaction). The results substantiated that vertical compaction exerted differential influences on the soil properties. Significant effects were observed between the average values of the control group and the other compaction levels in most measured parameters. Soil bulk density exhibited an average difference of 82.5 kgm-3, with a corresponding difference of 6 m-2 observed for crop count and a recorded difference of 0.046 kgm-2 for shoot biomass. However, no significant effect in terms of speed of emergence was recorded between the aforementioned compaction levels. The experimental findings serve as valuable resources for guiding further research into the interplay between soil compaction, soil dynamic properties, and canola growth.

Soil physical quality, more specifically soil compaction under cattle foot traffic caused by the intensive cattle grazing could cause long-term soil health problem for rangeland. Mature cattle can exert a static ground pressure of approximately 1.7 kg/cm2 of hoof-bearing area, which is equivalent or higher than the heavy-wheeled tractors. A little research has been conducted to understand the soil compaction under the cattle hoof. In addition, quantifying and visualizing the stress distribution in the top-soil layer is difficult to accomplish. To understand soil stress distribution, under the cattle hoof a discrete element model (DEM) will be developed. Model data will be calibrated and validated using laboratory experiments. A soil compaction test will be conducted using Loam soil for two different moisture contents. A predetermined soil mass for each soil moisture conditions was loosely filled into a square box (12”x12”'x15”) and the soil was compressed using a square plunger (150 mm) to the targeted soil bulk density levels of 1400 Mgm-3 on the bottom layer, 1550 Mg m-3 in the middle layer and 1250 Mg m-3 in the top layer. Soil resistance data will be measured using a cone penetrometer. A 3D printed life size cattle hoof will be used to apply compressive pressure on the compacted soil. Stress distribution under the cattle hoof for various compressive pressure, soil density, and soil moisture content will be determined using DEM. The results will be presented during the conference.

Obtaining information about spatially and temporally variable soil hydraulic properties is vital for many agricultural and environmental applications. However, challenges persist in acquiring such information due to the complexity, small-scale, and invasive nature of many of the current estimation methods. Our study investigated the potential of incorporating ground-penetrating radar (GPR) travel time data into a standardized infiltration procedure, like the Beerkan infiltration, to enhance estimates of soil hydraulic properties. The experiment was conducted on loamy sand-textured soil at Pasadena, Newfoundland, Canada, using a metal ring of 10 cm diameter and several doses of water of the same volume (200 mL). A surface GPR system with a center frequency of 500 MHz and 43 cm antenna offset was used to monitor wetting front movement during infiltration by collecting time-lapsed GPR traces every 5 s. Antenna separation of 43 cm was selected to clearly separate the direct ground wave from the air wave. The elapsed time required for complete infiltration of each volume of water was recorded. Estimated cumulative infiltration was obtained based on the GPR direct wave travel time relationship. The plot of the estimated cumulative infiltration with time was used to estimate soil-saturated hydraulic conductivity (Ks) and sorptivity (S) estimates according to the BEST-steady and BEST-intercept procedures. Preliminary results gave reasonable estimates of soil Ks and S based on the travel time of GPR direct waves and demonstrated the potential of obtaining soil hydraulic parameters from a convenient infiltration procedure.

Frequent and unpredictable occurrences of flood and drought events demand an efficient and sustainable water management system to cope with the moisture stress in field crops. A reliable design of combined irrigation and drainage system for the best- and worst-case scenario highly depends on soil water retention and permeability which depend on soil texture and structure. Soil structure is directly affected by management practices and crop root distribution. The objective of this study is to estimate soil hydraulic parameters in fine textured soil in Manitoba. HYDRUS inverse modelling coupled with PEST was used to estimate the van-Genuchten and Mualem soil hydraulic parameters. The observed soil water content determined at the site within 0-10, 10-30, 30-70 and 70-130 cm layers over the growing seasons from 2016 – 2019 under soybean-oat rotation was used for calibration and validation of the model. Results reflecting the changes in soil hydraulic parameters over the years will be presented along with its effect on water movement between the layers. The findings from this study will enhance the efficiency of subirrigation and drainage systems to produce a conducive environment for plant growth and performance.

Vertisolic soils (Vertisols) are pivotal for agricultural productivity in Manitoba due to their high fertility and superior moisture retention capabilities relative to other soil orders. However, managing Vertisols presents significant challenges due to their distinct swelling and shrinkage properties and low moisture buffer capacity. Consequently, these soils are prone to deformation, becoming excessively sticky and unworkable when wet, while they are rigid and develop cracks when dry, which severely restrict the window for field operations during the growing season. The behavior of Vertisols underscores the pressing need for innovative strategies to optimize agricultural practices and mitigate associated constraints. This requires a better understanding of their moisture dynamics as well as how they respond to extreme moisture conditions. The objective of this study was to investigate how Vertisols respond to extreme moisture relative to normal moisture conditions. Continuous soil moisture and weather data were collected from 17 study sites in the Red River Valley during the growing season (May to September) in 2018 – 2022. Soil water flux in the 0 - 5, 5 - 20, and 20 - 50-cm layers was determined. Results showing the soil water flux under different moisture conditions (extreme vs. normal) will be presented. Results from this study will contribute towards the development of effective soil water management strategies as well as adaption of agronomic management and field operations for sustainable crop production in Vertisols.

Excess soil moisture is typical of soils in Manitoba during the early growing season due to snowmelt and heavy rainfall. Managing soil moisture to attain optimal soil strength for trafficability is therefore crucial to ensure timely field operations in the region. Over the years, subsurface drainage has been the most popular approach for removal of excess soil water. However, this approach is not always feasible due to poor internal drainage and/or compromised soil structure. In this study, the potential of cover crops to improve soil strength for trafficability in Manitoba is explored. A multi-year study was initiated in the fall of 2020 near Cartwright, MB. Since fall 2022, rye has been grown at the site as a fall shoulder cover crop to assess its impact on soil moisture dynamics and its implications on soil strength for trafficability during spring field operations compared with no cover cropping. Continuous soil moisture measurements were taken in the 0-5, 5-15, 15-25, 25-35 and 45-55-cm layers. The critical soil moisture content for attaining soil strength sufficient to support trafficability was 90% of the lower plastic limit of the soil in the 0-25-cm layer. Preliminary results show that the fall rye cover crop significantly reduced soil moisture content in the 0-5-cm layer relative to no cover cropping. However, the fall shoulder cover crop fields did not meet the criterion for trafficability. Data on the impact of the 2023 fall rye cover crop on trafficability in spring 2024 will be analyzed and presented.