Part 6 · Capstone: Design Your Own Subsistence Farm
Site Survey and Sector Analysis
Draw a scale plan of your site and overlay every sector that moves: sun, wind, water, frost, fire and access.
You cannot design ground you have not drawn. The second deliverable is a survey and a sector analysis: a plan of your site to scale, with every force that moves across it marked. A design drawn only from memory will put the swale on the wrong contour and the garden in the frost pocket, and it will do it with total confidence.
What you produce
Two sheets, same scale, meant to be laid one over the other. The first is the base map: the boundary, the slope with contours, the existing trees, buildings, water, and the point where water enters and leaves. The second is the sector overlay: the arcs and arrows that cross the site from outside it. Draw both at the same scale, a square of ten feet to the inch is fine for 10,000 square feet, and put a north arrow and a scale bar on each.
A sector is a direction something comes from. Sun, wind, water, frost, fire, wildlife, noise, and the neighbours' eyes. You do not control a sector. You receive it. The design bends to the sector; it does not argue with it.
The exact format
A table of sectors, one row each, with four columns: sector, direction, when it arrives, what it brings.
| Sector | Direction | When | What it brings |
|---|---|---|---|
| Sun | south | all year | the warm face, earliest workable ground |
| Prevailing wind | west | most of the year | dries the soil, taxes the crop |
| Storm wind | northwest | winter | the destructive gusts |
| Water | the slope, top to bottom | every rain | the gift and the threat |
| Frost | still air, low corners | spring and autumn nights | the pocket that kills the seedling |
| Fire | uphill and downwind | dry season | the path a ground fire takes |
| Wildlife | the wood edge | all year | deer, boar, birds, the browsers |
Then the base map with contours. Find the contour with an A-frame and mark it in stakes or a spade line, the way the building chapter of the house design sets out, because a water structure laid by eye leaks. Draw the contour at one-foot intervals if the slope lets you, and draw where the water leaves the site.
Why the sectors come first
The same logic runs through the house's own account of the hill: on a slope, water and soil are one problem wearing two shirts. Where the water runs off instead of sinking in, the top of the slope dries and the bottom floods, and the topsoil goes with it. You cannot stop the flee before you have marked where it goes.
Worked example at the 10,000 square foot scale
Our 10,000 square foot bench, twelve percent south slope. The base map marks water entering at the top-left corner and leaving at the bottom-right, the two hedge gaps on the west edge as frost pockets, one mature oak at the north corner, and the shed at the bottom of the slope. The sector table reads: sun south, strongest from March to September; prevailing wind west; storm wind northwest, December to March; water downhill on every rain; frost settling in the two hedge gaps and the flat bottom corner; fire running uphill fast on a dry west wind; deer entering along the wood edge on the north.
Two things on that map already decide the design. The frost pocket at the bottom corner will not carry the early crop. The water that leaves at the bottom-right is water the farm paid for and handed away. Both belong in the plan before a single bed is drawn.
The test
The survey passes if it shows where the water enters and where it leaves, and if it marks the frost pocket. A plan that cannot say where the water leaves is rejected, because every terrace and swale downstream of that mistake will be in the wrong place. The second test is simpler: hand the map to someone who has walked the site with you and ask them whether they recognise it. If they cannot find their own way around it, redraw it.
Exercise
Lay out the contour
Build an A-frame from three sticks and a plumb line. Mark one contour across the full width of your site and peg it every ten feet. Photograph the pegged line. That line is where your first swale or fanya juu ditch will go in Lesson 603.
Fieldwork
Walk the hill in the rain
Walk the whole slope during the heaviest rain you can safely stand in, and mark where the water runs, pools, and sinks. Water is honest and a map drawn from it is more accurate than any you will draw dry. Never walk a slope in a storm with lightning, and never cross moving water above your knees.
Failure mode
The failure mode is a survey drawn from memory. A map made at the kitchen table shows the site you remember and the contours you assume, and it puts the swale on the wrong line with total confidence. Measure and peg every contour and every boundary before you draw. A design built on an unmeasured map fails in the first rain, and the rain does not read the drawing.
