4. Evaluation of different crop model-based approaches for variable rate nitrogen fertilization in winter wheat

Efficient nitrogen (N) fertilization management is a crucial aspect in today's agriculture. Farmers are commonly applying uniform fertilization rates without considering the spatial and temporal variability in the soil-plant-atmosphere continuum. Several site-specific approaches have been proposed over recent decades, including the use of proximal and remote sensing and crop simulation models for potential yield estimation. The present work is aimed at comparing different crop model-based variable rate nitrogen approaches using (1) historical weather data and (2) a combination of current + forecast weather data and normalized difference vegetation index (NDVI)-derived N uptake estimates to the farmer's uniform fertilization. Results showed that the variable N rate approaches had better agronomic efficiencies and crop yields than the uniform fertilization, leading to increased profitability.