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. IEEE journals and the American Society of Agricultural and Biological Engineers (ASABE) document consistent 5–15% yield gains on farms that integrate GIS into operational decisions versus those that manage uniformly at field scale.