News from Graduate Students Md. Nayem Hasan Munna and Brittany Multer
Understanding Soil Health through the Constant Head Method at the Lal Carbon Center
By Md. Nayem Hasan Munna
As autumn arrives and Ohio’s landscape begins to shift into fall colors, the Soil Physics lab at the Lal Carbon Center is bustling with activity. Recently, I undertook an analysis to measure the saturated hydraulic conductivity of various soil samples using the constant head method. This experiment sheds light on how water moves through soil—a key factor influencing everything from plant growth to erosion control.
So, what exactly is saturated hydraulic conductivity, and how does the constant head method help us measure it? Saturated hydraulic conductivity is a measure of the soil’s ability to transmit water when fully saturated. The constant head method is particularly useful for soils with relatively high hydraulic conductivity, like sands and well-aggregated loams. In this method, water is maintained at a constant height above the soil sample, and we measure the rate at which it flows through the soil under steady conditions.
In the lab, I worked with soil samples from a no-till field that’s part of an ongoing study on organic amendments, such as compost, manure, and cover crops. These treatments are applied to improve soil health by enhancing soil organic carbon levels. By employing the constant head method, I aimed to understand how these organic amendments influence the soil’s water flow dynamics.
The process itself is meticulous yet revealing. After saturating the soil samples, I set up the constant head apparatus, which allows water to maintain a consistent height above each soil core. As water flows steadily through the soil, I
monitor and record the outflow rate over time. This provides a direct measurement of the soil’s ability to transmit water, with higher conductivity values indicating that water moves more freely through the soil.
The results tell a compelling story. Soils enriched with organic amendments, like compost, often exhibit higher saturated hydraulic conductivity, allowing water to flow efficiently. This improved water movement supports root health by ensuring an aerated, moist environment—ideal for crop growth. In contrast, soils without organic amendments sometimes show lower conductivity, indicating compacted soil structures where water flow is restricted. This can lead to issues like poor root development and increased susceptibility to erosion.
These insights are valuable not only for our understanding of soil physical properties but also for broader sustainability efforts. Soils with improved hydraulic conductivity are better equipped to handle heavy rainfall, reduce runoff, and improve resilience against droughts. This research at the Lal Carbon Center contributes to sustainable agricultural practices in Ohio by providing data that can help farmers and conservationists alike.
Reflecting on this experience, I’m inspired by the connections between soil health, water management, and sustainable agriculture. The constant head method may be a simple test, but it provides a powerful window into the inner workings of soil and its vital role in supporting resilient ecosystems.
Environmental Impacts of Concrete Weathering in Soil
By Brittany Multer Hopkins
C-FARM Graduate Student Brittany Multer Hopkins is studying the carbon capture potential and environmental impacts of concrete weathering in soil. Sampling continues at her plots at Waterman Agricultural and Natural Resources Laboratory and will wrap up in November. Brittany will be presenting a poster on her research at the 2024 ASA, CSSA, SSSA International Annual Meeting in San Antonio, Texas in November.