Manure vs. Fertilizer - New Research Shows Water Quality Impact

By Blake Jackson

Kentucky researchers are examining how different nutrient management strategies affect both soil health and water quality in corn production systems.

A recent peer-reviewed study from Kentucky State University provides new field-based data that could help farmers make more informed decisions about fertilizer and manure use.

Published on May 7 in Frontiers in Soil Science, the study, titled “Effects of nutrient management on soil health and leachate water quality in a corn agroecosystem,” evaluated the impacts of dairy manure, composted dairy manure, and synthetic fertilizer at the university’s Harold R. Benson Research and Demonstration Farm.

The research focused on a key question for crop producers: how to maintain strong crop performance while minimizing nutrient losses that can affect nearby water resources.

The project was led by Sandeep Airee and Asmita Bhandari, both graduates of Kentucky State University’s Environmental Science and Technology master’s program who are now pursuing doctoral degrees at Washington State University.

Additional contributors included Dr. Anuj Chiluwal, assistant professor of agronomy, Dr. Maheteme Gebremedhin, chair of the School of Agriculture and Natural Resources, and former faculty member Dr. Atanu Mukherjee.

Researchers conducted the trial on a 1.77-acre field using dairy manure, composted dairy manure, and synthetic fertilizer treatments, each replicated four times.

Soil and leachate water samples were collected throughout the growing season at depths of 10 and 20 centimeters to assess changes in soil properties and nutrient movement.

Results showed that manure applications improved soil aggregation and increased organic matter levels compared to synthetic fertilizer. Compost also enhanced the soil’s specific surface area, which can contribute to better nutrient retention and overall soil function.

Water quality findings revealed notable differences among treatments. Synthetic fertilizer plots recorded significantly higher nitrate concentrations in leachate water at both sampling depths.

Researchers also detected increased phosphate movement from fertilizer-treated areas during certain sampling periods.

The study found nitrate to be considerably more mobile than phosphate or potassium, highlighting the importance of careful nitrogen management. While the first-year results are encouraging, researchers noted that longer-term monitoring is needed.

The findings represent the initial phase of a four-year project examining how fertility practices influence soil quality, nutrient retention, and environmental sustainability in Kentucky farming systems.

Photo Credit: gettyimages-oticki