GIS

A GIS organizes data as layers tied to geographic coordinates. A typical farm GIS might include 10–30 layers: field boundaries, soil survey (USDA SSURGO), elevation and slope, historical yield monitor data, NDVI imagery time series (see ndvi), weather station locations, grid soil-sample points, irrigation zones, and drainage infrastructure. Each layer can be queried independently or combined through spatial analysis — for example, overlaying low-yield zones with low NDVI and high clay content identifies drainage-limited areas that need tile installation or crop-switch.

The open-source GIS ecosystem (QGIS, GDAL, PostGIS) has dramatically lowered the cost of agricultural GIS. Twenty years ago, agricultural GIS required ESRI ArcGIS licenses costing €1,000–5,000 per seat plus custom training. Today, QGIS is free, Sentinel-2 and Landsat imagery is free, USDA soil and CDL (crop data layer) data is free, and web-based platforms integrate GIS capability directly into farm management software without requiring desktop installation.

GIS-driven workflows transform several farm operations. Prescription maps for variable rate application (see variable-rate-application) are built in GIS by defining management zones and assigning application rates per zone, then exported to tractor controllers as shapefiles or ISO-XML. Yield monitors write georeferenced yield readings every few seconds during harvest — GIS interpolates these points into continuous yield maps that reveal multi-year productivity patterns. Drainage design uses GIS topographic analysis to route tile lines along natural flow paths. Integrating GIS into operational decisions lets a farm target management to the specific parts of a field that need it, rather than treating the whole field as one uniform block.