Investigating the Fate of Nitrogen Fertilizer in Perennial Groundcover Corn Cropping Systems Using 15N Stable Isotope Labeling

Issue

Sustainable agricultural practices are crucial for meeting global food demand while protecting the environment. Nitrogen (N) fertilizer is often necessary for optimal plant growth but can lead to environmental issues if used inefficiently. Traditional cover crops can help mitigate these issues but have limitations such as economic constraints and potential yield reductions due to competition for resources.

Perennial grass groundcover (PGC) offers unique advantages, including continuous soil coverage, reduced soil disturbance, enhanced soil health, biodiversity, and ecosystem resilience. Eliminating the need for yearly replanting reduces economic risks. Nonetheless, a knowledge gap exists regarding N dynamics in PGC systems.

Objective

Objectives include evaluating corn N fertilizer use efficiency, investigating competition for N fertilizer between corn and PGC, and quantifying N fertilizer leaching below the root zone. Using 15N stable isotope labeling will allow for precise tracking of N fertilizer. 15N is a form of N that acts like a tracer, allowing us to follow its path after application to help measure how much N fertilizer the corn plants use, how much stays in the soil and how much might leach into the groundwater.Understanding N fertilizer fate in PGC systems will help develop management recommendations for farmers to maintain or increase productivity while reducing environmental impacts.

Approach

This research aims to improve N management in PGC systems using advanced techniques to track N fertilizer movement. The study involves planting corn into an established Kentucky bluegrass/perennial ryegrass groundcover and evaluating different PGC system approaches: conventional tillage, strip-tillage with chemically suppressed grass, and strip-tillage with non-suppressed grass. Each plot will receive three N treatments: no N, urea, and 15N labeled urea.

Plant and soil samples will be collected at various growth stages to analyze for 15N to determine N fertilizer content. Lysimeters will collect soil water samples following rainfall events to estimate N fertilizer leaching.