Graduate Exit Seminar - Hengkang Zhao

Plan to join Hengkang Zhao's graduate exit seminar on October 2, 2024, at 8:00 am in Kottman Hall 333C or via Zoom. Hengkang will present, "Temporal Changes of Soil Physical Properties in Relation to Tillage and Drainage."

Abstract: Soil physical properties play a crucial role in agricultural productivity and environmental sustainability. This study investigated the seasonal dynamics of soil physical properties under different tillage and drainage practices in poorly drained soils of Ohio, focusing on their interrelationships with soil hydraulic properties, soil structure, crop growth, and climate across various agricultural production stages, and their potential impact on soil physical quality index (SQI). Soils were sampled under long-term tillage (no-till, NT vs chisel-till, T) and drainage (drained, D vs non-drained, ND) management. Intact soil cores and undisturbed bulk samples were collected at 3 depths in different seasons. The results showed that NT practices generally improved soil structure and aggregation, they also presented challenges such as seasonal variations on saturated hydraulic conductivity, and higher penetration resistance in subsoils. The variable effects of drainage practices highlight the need for site-specific management strategies. NT significantly benefited crop height both for soybean and maize during their development, but the effects on crop yield varied. NT improved soybean yield, while ND enhanced maize yield. The SQI developed in this study proved to be both purpose-oriented and dependent on temporal and depth factors. The SQI showed positive correlations with crop yield during growing seasons but was less reflective of soil physical functions related to yield during fallow periods. This emphasizes the need for dynamic soil quality assessments that account for crop growth stages and seasonal variations. In conclusion, the findings contribute to the understanding of sustainable soil management particularly in poorly drained soils, and highlight the importance of considering temporal dynamics in soil quality assessments.

Advisor: Dr. Rattan Lal