Spatial variability in fields
Within a single field, soil fertility, moisture, and yield often vary dramatically. Precision agriculture maps this variability and applies inputs at rates matched to each zone rather than uniform broadcast.
Data layers
- Yield maps — combine-mounted sensors record harvest mass per GPS coordinate.
- Soil sampling grids — interpolate pH, phosphorus, potassium across the field.
- Remote sensing — satellite or drone imagery tracks crop vigor (NDVI) through season.
Variable rate application
Fertilizer spreaders and seeders adjust rate on the fly from prescription maps. Benefits include reduced over-application on rich zones and targeted correction of deficient areas. ROI depends on variability magnitude — highly uniform fields gain less.
Limitations
Data integration requires software literacy and calibration. Prescription maps are not self-interpreting — agronomic judgment validates whether low NDVI reflects nitrogen deficiency, disease, or planting error.