Aerial Remote Sensing for Nitrogen Rate Optimization in Soft Red Winter Wheat Production

Overview

This project validates an aerial remote sensing approach for optimizing nitrogen (N) fertilizer applications in soft red winter wheat production. Traditional nitrogen rate decisions at growth stage 25 rely on manual tiller counting, which is labor-intensive, time-consuming, and prone to inaccuracy due to field variability. Research has demonstrated that aerial remote sensing indices, specifically Normalized Difference Vegetation Index (NDVI) and Normalized Difference Red Edge (NDRE), can accurately estimate tiller number and produce equivalent nitrogen recommendations. This initiative seeks to validate these findings at commercial scale across Eastern Virginia grower fields, while quantifying the economic returns of the approach for wheat producers.

Technical specifications

Core methodology:

• Aerial remote sensing captures NDVI and NDRE indices across wheat fields at growth stage 25
• Vegetation indices are correlated with tiller density to determine whether nitrogen application is needed
• Decision threshold: tiller counts exceeding 1000 m⁻² at growth stage 25 indicate no nitrogen application is required
• UAV-based data collection enables rapid field-scale assessment

Validated performance from small plot studies:

• NDVI estimated tiller count with R² = 0.75 accuracy
• NDRE estimated tiller count with R² = 0.71 accuracy
• Both indices produced nitrogen recommendations equivalent to the traditional tiller counting method
• Grain yields from sensor-based recommendations matched conventional methods at approximately 6700 kg ha⁻¹

Current validation scope:

• 20 grower sites across Eastern Virginia
• Two-year field trial period
• Comparison of grain yields from nitrogen rates recommended by tiller counting versus aerial sensing methods

Technology readiness level

The technology has completed initial validation in a four site-year study using small research plots in Virginia, demonstrating statistical equivalence between aerial sensing and traditional tiller counting methods. The current proposal represents the critical transition to large-scale grower field validation. Upon successful completion of this two-year validation across 20 commercial sites, the technology will be positioned for direct adoption by wheat producers and crop advisors. The project seeks partnership support for fertilizer costs at participating grower sites, travel expenses, UAV consumables, and partial personnel funding for data collection and analysis.