Map a site’s farming potential by dividing the ground into cells, testing the soil in each, and drawing slope, frost risk and water access on the same sketch map. Loam on a gentle slope with irrigation water close by is the best farmland; sandy, steep, hollow or frost-prone cells are poor, and the best building ground is often the land you can spare from that map.
Surveying candidate fields around a settlement site and recording soil, slope, frost and water on a map to rank them for growing food.
Good Farmland Is a Combination, So It Must Be Drawn as One
The carrier lists the pieces: loam for agriculture, concave slopes for farming (they collect water), 2-8% grade for drainage, no frost pockets for tender crops, and water within reach. No single test says whether a field is good. A map that overlays them shows it. It also shows conflicts: the best soil may sit in a frost pocket, and the best building ground may be the best farmland.
What You Need
- Stakes and a measuring line — to lay out a grid. See Chain and Tape or use a measured rope.
- A shovel and a jar — see Soil Composition Testing.
- Paper and charcoal — see Sketch Mapping.
Method: Grid, Test, Overlay
Step 1: Lay a grid Pace or measure out cells across the candidate area. A 20 m cell is a practical choice for this work (a chosen compromise between effort and detail, not a standard). At 20 m, a hectare (100 m x 100 m) holds 5 x 5 = 25 cells.
Step 2: Test each cell Dig one test hole per cell. Record topsoil depth, texture (jar and ribbon test), stones, and signs of waterlogging.
Step 3: Record slope and shape For each cell, note the grade (see Slope & Drainage Assessment), whether convex or concave, and the compass direction it faces.
Step 4: Note frost and water Mark hollows where cold air pools. See Cold Air Drainage & Frost Pockets. Mark distance to water and whether it can be delivered by gravity.
Step 5: Colour the map Use three classes only: good (loam, 2-8% grade, no frost pocket), usable (needs amendment or has one fault), poor (steep, waterlogged, sandy or frost-prone). Keep the map; add to it each season.
Worked Example
A 2-hectare candidate area is 200 m x 100 m.
- At 20 m cells: 10 x 5 = 50 cells, 50 test holes.
- If 30 cells are good, 12 usable and 8 poor, then 30 / 50 = 60% of the area is good: 1.2 hectares.
- One hectare is 10,000 m2, so 1.2 hectares is 12,000 m2.
How many hectares the settlement needs depends on crops, climate and population, and is not a figure to take from this page. See Farming Basics and Planning and Mapping Crop Rotation Plots.
Common Mistakes
- Mapping only the best-looking field — compare options.
- One visit — frost pockets and waterlogging show only in the right season.
- Putting buildings on the best soil — buildings can go on poorer ground. The carrier wants both building clay and farming loam within reasonable distance of the site, not both on the same cells.
Safety
Land of unknown history may be contaminated
Do not grow food on ground near former industrial sites, dumps, fuel stores or burnt buildings without careful checking, and keep children and animals away from old chemical containers. Wash vegetables from new ground well in the first seasons.
What’s Next
- Learn next: Farming Basics — what to do with the ground once chosen
- Combine with: Sun Exposure & Shadows — checking field light