Luck versus Skill: Is Nitrogen Balance in Irrigated Maize Fields Driven by Persistent or Random Factors?

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Nitrogen (N) balance indicates potential N losses to the environment.
• N balance magnitude is influenced by both random and persistent factors over time.

Purpose of the Study:

• Assess the influence of persistent factors on N balance variation in US Corn Belt irrigated maize fields.
• Identify underlying drivers of N balance magnitude and persistence.

Main Methods:

• Analyzed N balance across irrigated maize fields in the US Corn Belt.
• Compared N balance in "ranking" (high N balance) and "nonranking" years within the same fields.
• Investigated associations between N balance persistence and field management practices.

Main Results:

• Persistent factors explained up to 50% of the variation in N balance.
• 70% of fields with N surplus in one year also showed surplus in other years.
• Continuous maize cultivation and higher N inputs without yield benefit were linked to persistent N surplus.

Conclusions:

• Significant room exists to reduce excess nitrogen in producer fields through improved management.
• Findings provide a basis for setting priorities and informing agricultural policy related to nitrogen use.
• Addressing the mismatch between actual and recommended nitrogen rates is crucial for reducing environmental N losses.