Which set of practices best describes how NUE can be improved in field crops?

• A. Precise timing and splitting applications, site-specific management, correct pH, using stabilized or slow-release forms, and selecting appropriate cultivars.
• B. Applying fertilizer uniformly across fields based on average requirements.
• C. Increasing irrigation frequency without regard to crop stage.
• D. Relying on soil testing alone without adjusting application.

Answer: (C)

Improving nitrogen use efficiency (NUE) in field crops comes from aligning nitrogen supply with the crop’s actual needs while minimizing losses. The best approach combines timing and placement with the crop’s growth stages and soil conditions. Precisely timing and splitting fertilizer applications ensures nitrogen is available when the plant is actively taking it up, rather than all at once or too late. Site-specific management tailors inputs to the variability within a field, so different areas get the right amount according to soil fertility and drainage. Maintaining an appropriate soil pH helps nutrients become available to plants and supports beneficial microbial activity that aids nutrient cycling. Using stabilized or slow-release forms lowers losses from volatilization and leaching, especially in soils prone to such losses. Choosing cultivars with better nitrogen efficiency or uptake characteristics can further improve overall NUE by making more of the available nitrogen accessible to the plant.

In contrast, applying fertilizer uniformly across a field based on an average requirement ignores spatial variability and often results in over- or under-fertilization in different zones. Increasing irrigation frequency without regard to crop stage can enhance nutrient losses through leaching and runoff. Relying on soil testing alone without translating the data into adjusted management actions leaves potential improvements unrealized.