Soil Fertility

How Fertility Works

Every individual farm cell tracks its own soil fertility — a value from 0 to 1 (0% to 100%). All cells start at full fertility. Each year a crop is grown, the soil drains a little. The yield at harvest is multiplied by the cell's current fertility, so a cell at 50% fertility produces roughly half the normal output.

Fallow land (unplanted cells) recovers slowly on its own at about +5% per year. Composting accelerates recovery significantly. The Y key toggles a visual overlay showing fertility across all your farms: green = rich, yellow = healthy, brown = exhausted.

Crop Rotation Families

Each crop belongs to a rotation family. Growing the same family in the same cell for multiple consecutive years increases blight risk — a chance that individual cells produce nothing at harvest that year.

Blight risk per cell = (consecutive years in same family − 1) × 15%, multiplied by your difficulty setting. On medium difficulty, year 2 is 15% per cell, year 3 is 30%, and so on. Switching to any other family resets the counter to zero.

Difficulty and Fertility

Your map's difficulty setting affects how aggressive fertility and blight mechanics are:

Composting

Composting is the most direct way to restore exhausted soil. The chain works as follows:

Livestock produce manure passively each cycle. Cattle produce the most, followed by pigs, sheep, and chickens. The Compost Yard converts 3 manure into 1 compost. Enable composting on each farm via its panel to have citizens automatically haul compost there each spring.

Cover Crops: Clover

Clover is a special farm crop that produces no food — but it restores fertility and resets the rotation counter. Planting clover on an exhausted grain field for one year:

• Restores approximately 20% fertility across all planted cells
• Resets the consecutive-year counter for that family
• Costs nothing except the land and the labour

Clover is classified as a legume, so a grain→clover→grain rotation treats each grain year as year 1 of a fresh cycle — no blight, soil recovering instead of depleting.

There's a further bonus: the first grain planted after clover receives a +20% yield boost for that harvest. The legume enrichment primes the soil. Plant clover one year, plant a grain the next, and you get restored fertility, reset blight risk, and a better harvest all at once.

Infestation

Farms and pastures can be struck by infestation — pests that move in and cut output in half for 15 to 25 days before naturally clearing. An infested building shows a 🐛 icon above it.

Infestation isn't triggered by the player's rotation or management decisions the way blight and disease are — it's a random event that can happen to any farm or pasture. The main protection is having enough farm coverage that losing half the output of one field for a few weeks doesn't cause a shortage. Spreading production across several smaller farms is more resilient than concentrating it in one large one.

Crop Disease

Disease is a separate and harsher mechanic from the blight roll. Each Summer, a scan checks for farms that have grown the same crop family for too many consecutive years. Farms that cross the threshold can become diseased:

• A diseased farm shows a 🦠 status icon above the building.
• The affected farm yields only 40% of normal output at harvest — worse than any blight roll.
• On Hard difficulty, disease can spread to adjacent farms in the same Summer scan.
• Rotating to a different crop family for one season clears the disease.

Farm Status Indicators

Each farm building panel shows a Soil status line indicating the average fertility of its cells: Rich, Healthy, Tired, or Exhausted. If blight risk is significant, the panel also shows the current percentage. A 🍂 icon floats above the building itself when average fertility drops below 30% or rotation risk reaches 30%.

Press Y to toggle the per-cell fertility colour overlay across all farm footprints at once.