Monitoring spatial dynamics of phosphorus use efficiency in cropped fields

Nutrient loss from cropped fields, especially phosphorus (P) loss, is a major environmental concern due to its negative impacts downstream. Phosphorus use efficiency (PUE) is an important metric in evaluating crop response to P-fertilizer applications and improving P runoff loss from cropped fields. The objective of this study is to demonstrate the development of PUE assessments from cropped fields and apply those metrics to provide geospatially explicit PUE across the fields. The work was conducted at a research farm near Riesel, Texas, USA, where the fields are managed with various levels of agronomic conservation adoption. Precision agricultural technologies are used to record planting, fertilizing, and harvesting (total yield and grain quality), and soil spatial variability assessment. Five sampling points were located in each field where intensive soil and crop measurements were recorded. Grain yield and quality data from the harvesting combine were compared to ground-truthed data from the sampling points in each field to determine crop P removal in grain. These data were then used to predict and map the PUE across the fields using a machine-learning technique. This study showcased an efficient way of monitoring the spatial aspects of PUE in agricultural fields that may improve fertility strategies, thereby leading to improved farm profitability and less P runoff from cropped fields.