Week 3: Mushrooms: substrate, yield and what to measure
What a household fruiting operation really contributes, and where the substrate goes afterwards.
Mushrooms are the first of the biological modules, and they are a useful disappointment. Sized honestly from biological efficiency, a household fruiting operation contributes a fraction of a per cent of the year's energy — so the interesting output is not the food, it is the five kilograms of spent substrate that leave for every kilogram picked. That substrate is a genuinely good soil input and a genuinely bad insect feed, and knowing which is the week's real content. Brisbane leads, because it is the site where some oyster species fruits in all twelve months and the binding constraint turns out to be strata rules rather than biology. The yields here come from the literature with a stated confidence; what your client's own prunings supply is a measurement question you carry into Assignment 1.
This week
- Lecture, 8 March 2027
- Mushrooms are a converter, not a cropWeek 3 — biological efficiency, species temperature bands, and what happens to five kilograms of spent substrate for every kilogram you pick
- Tutorial, 11 March 2027
- Substrate in, substrate outWeek 3 tutorial — size a fruiting operation from the substrate you actually have, and account for the five kilograms that leave for every kilogram picked
- Assessed, due 11 March 2027
- Quiz 1: Loop thinking, water-limited yield and mycology4 % of the course mark. Week 3 — the closure definition, the monthly water balance behind every yield figure, and what mushrooms actually contribute
- Worked example
- BrisbaneThe Patels' home leads this week, because its climate makes this subsystem easy. All five homes are compared on the lecture page.
What you leave with
A substrate mass balance with both arrows drawn: substrate in, mushrooms out, spent substrate to soil and compost.
You have finished the tutorial when all of this is true, and you can tell without asking anyone:
- your substrate supply is estimated from your own site's prunings and a stated import, not assumed
- your mushroom yield uses a biological efficiency inside the published range, with the figure named
- spent substrate appears as an output with a mass and a destination
- you have not drawn an arrow from spent substrate to the insect unit
- your sheet records that this week's yield figures carry a medium confidence label
Assignment milestone
Quiz 1 (4 %), sat at the start of the tutorial, on weeks 1–3.
Where this sits
You meet the client and work through each candidate system — garden, mushrooms, insects, fish, preservation — far enough to know what it needs and what would have to be measured before anyone spent money on it. Every calculation in these weeks is a scoping estimate on published figures, not a claim about this house.
Expected effort
About 8 hours this week: 2 h lecture and notes, 2 h tutorial, 1 h preparation and quiz, 3 h assignment 1. The assignment hours go into: Substrate balance, and what would have to be measured to trust it.
A planning guide from the semester planner, not a requirement and not a measurement of anyone. Tutorial submission sits inside the tutorial hours and the quiz inside preparation; neither is counted twice.