Knowledge Base · Soil Field Guide

Read your soil
like a paint swatch.

Grab a handful of your dirt. Scroll until you see a photo that matches. Every card tells you what you're looking at, what it means for growing, and what to do next.

Every photo below is a real, documented soil sample — no stock filler, no AI images. Credits at the bottom of the page.

Before you match · 60 seconds

Take a real sample first

1

Dig down 6 inches (15 cm). Surface dirt lies — it's sun-bleached and dried out. The real story is below.

2

Grab a golf-ball-sized handful. Pick out rocks, roots, and mulch.

3

Moisten it slightly — damp, not muddy. Color and texture both read truer when moist.

Step 01 · Match the color

What color is it?

Soil color is chemistry you can see. Hold your handful next to these photos and find your match.

Test pit showing deep black organic-rich topsoil with a measuring tape

Dark brown to black

The color of organic matter

Deep, dark soil means decomposed plant material (humus) has built up. This is the soil everyone wants — it holds water, feeds microbes, and releases nutrients steadily.

What to do: Protect it. Keep it covered with mulch or living plants, don't till it, and it will keep working for you.

Exposed red lateritic soil on a green tropical hillside in Guam

Red to orange

Iron oxide — rust, literally

Red means iron minerals that have been exposed to air — a sign of good drainage and heavy weathering. Very common in the tropics and the Caribbean. Often low in organic matter and slightly acidic.

What to do: Drainage is usually fine; fertility is the project. Build organic matter with compost, mulch heavy, and consider a pH test before planting.

Pale sandy soil on open ground with pine trees

Pale tan to whitish

Sand-heavy, leached, or both

Light-colored soil has little organic matter, and rain washes nutrients through it fast. Water drains almost instantly — great for root crops, brutal for thirsty plants.

What to do: Add organic matter relentlessly — compost, manure, cover crops. It's the only thing that makes sand hold water and nutrients.

Close-up of gray soil streaked with rust-orange mottles next to a folding ruler

Gray with rust flecks

Mottling — the waterlogging fingerprint

Gray soil streaked or spotted with orange means the ground sits waterlogged part of the year, then dries out. Solid gray or blue-gray with a swampy smell means it's waterlogged most of the time. Roots drown in it.

What to do: Don't fight it with the wrong plants. Raise beds, plant water-tolerant species, or redirect the water. This is exactly what a land audit maps out.

Roadside soil profile showing dark topsoil over an orange band over pale subsoil

Bands of color as you dig

Soil horizons — your land's biography

Dig a knee-deep hole and you'll usually see layers: dark topsoil, a colored middle, pale parent material below. The thickness of that dark top layer is the single fastest read on how much fertile soil you actually have. Two inches and fourteen inches are very different starting points.

What to do: Measure your dark layer. Thin topsoil means build up (mulch, compost, chop-and-drop) before you plant anything demanding.

Step 02 · Feel the texture

Now squeeze it.

Color tells you chemistry; texture tells you how water and roots will move. You only need your hands.

The 10-second squeeze test
Falls apart → Sand

Squeeze a moist handful and open your hand. If it crumbles immediately and feels gritty, you're sandy. Fast drainage, low nutrient holding.

Holds, then crumbles → Loam

Forms a ball that breaks apart when poked. Feels slightly gritty and slightly smooth. This is the sweet spot — most crops love it.

Ribbons → Clay

Roll it between thumb and finger. If it presses into a shiny ribbon an inch or longer, you've got clay. Nutrient-rich but slow-draining and easily compacted.

Two hands holding chunky red-brown clay soil aggregates

Dry clay: hard clumps

If your soil dries into dense clods you could throw through a window, that's clay structure. It's not bad soil — it's rich soil that needs organic matter and zero tilling to open up.

Red clay soil caked thickly onto a motorcycle wheel in the wet season

Wet clay: sticks to everything

Clay announces itself in the wet season — it cakes onto boots, tools, and tires. If walking your land after rain adds two pounds to each foot, plan drainage and raised planting zones before anything else.

Want a precise answer? · The jar test

Measure your mix overnight

  1. Fill a straight-sided jar ⅓ with soil, top up with water, add a drop of dish soap.
  2. Shake hard for 2 minutes, then set it down where it won't be moved.
  3. Sand settles in 1 minute — mark the line. Silt settles in 2 hours — mark again. Clay settles over 1–2 days.
  4. Measure each band, divide by total depth, and find your percentages on the triangle.

Example: 50% sand / 30% silt / 20% clay lands in "loam" — dead center, right where you want to be.

USDA soil texture triangle showing clay, silt, and sand percentage classes
Step 03 · Watch the water

Where does the rain go?

Color and texture predict drainage — these two checks confirm it.

A dug test pit in a grass field with water pooled at the bottom and a spade

The percolation test

Dig a hole one foot deep, fill it with water, let it drain, then fill it again and time it. Draining 1–3 inches per hour is ideal. Under 1 inch per hour — or standing water like this pit — means poor drainage; over 4 means it drains too fast to hold moisture.

What to do: Slow drainers get raised beds, swales, or water-loving species. Fast drainers get organic matter and heavy mulch.

Farm field with standing water and mud among young green crops

Surface signs after rain

Walk your land 24 hours after a good rain. Puddles that linger, shiny compacted paths, moss, sedges, or rushes all point to water sitting where roots need air.

What to do: Map the wet spots — they're design information, not problems. A pond, a swale, or a water-tolerant guild might belong exactly there.

Matched your soil? Now read your whole property.

The free land audit takes what you just learned and maps it across your land — soil, water, sun, slope, and what to plant where.

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