Drainage volume drives dissolved organic matter leaching loss in a corn system

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Leaching of dissolved organic matter (DOM) is crucial for carbon translocation in terrestrial ecosystems.
• Research on DOM leaching dynamics in subtropical row-crop systems is limited, with most studies focusing on wetlands and forests.
• Understanding drivers of DOM leaching is essential for managing agroecosystems.

Purpose of the Study:

• To assess dissolved organic carbon (DOC) leaching loss and composition in a subtropical corn system.
• To investigate the influence of environmental and management drivers on DOM leaching dynamics.
• To address the knowledge gap regarding DOM leaching in subtropical row-crop agriculture.

Main Methods:

• Utilized lysimeter observations over two years in a Florida corn system with varying nitrogen fertilization rates.
• Quantified cumulative DOC and total nitrogen (TN) loss across growing and cover crop seasons.
• Analyzed DOC concentration and composition in relation to drainage volume and seasonal events.

Main Results:

• Cumulative DOC loss ranged from 9.74 to 27.56 kg ha⁻¹, with Hurricane Debby causing extreme DOC and TN loss.
• DOC loss was linearly correlated with drainage volume, though the relationship strength varied seasonally.
• DOM composition shifted seasonally, reflecting changes in DOC sources, and was influenced by events like soil disking and hurricanes.

Conclusions:

• Drainage volume is the primary driver of DOC leaching in this subtropical agroecosystem.
• Seasonal DOM composition changes indicate shifts in DOC sources, not consistently influenced by nitrogen fertilization.
• Hurricanes and groundwater intrusion are significant factors regulating DOM and TN dynamics in these systems.