Science-Based Zone Mapping for Site-Specific N Management in Dryland Wheat-Based Cropping Systems On Complex, Pacific Northwest Palouse Landscapes.

Increasing N use efficiency (NUE) through precision management of agricultural N in space and time will play a central role in the reduction of agricultural N₂O emissions and NO₃ losses. Precision N management requires a greater understanding of the spatio-temporal variability of factors supporting N management decisions such as crop yield, water and N availability, utilization and losses.

In this presentation, we outline initial zone mapping approaches as part of a five-year Site-Specific Climate-Friendly Farming (SCF) project. Using a combination of stratification and space-filling techniques, we selected 36 representative and distributed measurement locations each in four grower fields that span the precipitation gradient across the Pacific Northwest Palouse region. At these locations we have monitored soil moisture dynamics and N availability. We stratify grower fields into zones with the objective of maximizing the statistical explanation of these target variables using terrain indices, remote sensing indices, and proximal soil sensing data (e.g. from electromagnetic induction and VisNIR penetrometer).