Score: 0
Funds: 300
Spring Y1
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About Acre Algebra

Grow crops, balance N-P-K and pH, rotate legumes and keep fertilizer runoff out of the creek in this free online soil science game.

Acre Algebra is a soil science game that turns every field into a living chemistry set. You inherit a small farm where each plot has its own N-P-K nutrient levels, pH and organic matter, and you must grow corn, wheat, soy, potatoes, tomatoes and clover while keeping the local creek healthy. The soil is not a backdrop: it is the stat sheet that decides whether your crops thrive or starve.

Every mechanic maps to a real biogeochemical process. Corn is a heavy nitrogen feeder that mines soil N fast, while legumes like soybean and clover host Rhizobium bacteria that fix atmospheric N2 into plant-available ammonia, which is the real reason farmers rotate crops. Soil pH controls nutrient availability: acid-hating crops stall below their range and potatoes actually prefer slightly acidic ground. Compost feeds microbes that slowly mineralize nutrients and build organic matter, while synthetic fertilizer delivers instant NPK but sends nitrate runoff into the creek, where it drives eutrophication and algal blooms.

These are the same trade-offs real agronomists manage. Buffer strips of vegetation along waterways trap runoff before it reaches the stream, cover crops prevent erosion and add green manure when plowed under, and monoculture invites pest build-up because specialist insects like aphids find the same host year after year. The contract deadlines mirror a farmer's real planning problem: hit yield targets without exceeding an environmental budget.

Key Science Concepts

What You'll Learn

Grade Level: Middle School, High School

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How to play

  1. Inspect Soil Tap any plot with no tool armed to read its soil report: N-P-K levels, pH and organic matter. Every plot starts different!
  2. Plant & Match Pick a seed in the dock, tap an empty plot. Match crops to the soil: potatoes like acid, tomatoes crave potassium, corn gulps nitrogen.
  3. Rotate & Rest Legumes like soy and clover fix nitrogen back into the soil. Rotate crops to recharge fields and break pest cycles. Repeating a crop invites aphids!
  4. Amend Wisely Fertilizer is instant NPK but runoff pollutes the creek. Compost builds organic matter slowly and lime raises pH. Crops on the creek-side buffer plots trap runoff!
  5. Harvest & Contracts Tap mature crops with the Harvest tool to sell them. Fill the contract quota before its deadline for bonus funds and score.
  6. Guard the Creek Watch Creek Health in the HUD. Algal blooms cost big fines and a dead creek ends the run. Tap the gauge for an emergency cleanup boost.
  7. Explore the Farm Drag the map to pan and pinch or scroll to zoom across every field. The minimap in the corner jumps you anywhere on the farm.

Frequently asked questions

Is Acre Algebra free to play?
Yes. Acre Algebra is completely free to play in your browser. There is no download, install or account needed.
What grade level is Acre Algebra for?
Acre Algebra is designed for Middle School, High School students and works well as a classroom activity or homework.
Does Acre Algebra work on phones and tablets?
Yes. Acre Algebra runs in any modern browser on desktop computers, Chromebooks, tablets and phones in landscape mode.

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