Fertilizer Synthesizer

The Fertilizer Synthesizer is a midgame ranching-adjacent farming building that turns Dirt, Polluted Water, and Phosphorite into Fertilizer for crops. It is a straightforward way to mass-produce Fertilizer for farmland, and it is most useful once a colony has a steady supply chain for its inputs.

When running continuously, one Fertilizer Synthesizer produces 72 kg of Fertilizer per cycle, equal to 14.4 uses of Micronutrient Fertilizer. To do that, it consumes 39 kg of Dirt, 23.4 kg of Polluted Water, and 15.6 kg of Phosphorite per cycle. That input cost is efficient enough that the building is often described as a resource-saving way to turn several renewable materials into crop support.

The ingredients can all be supplied renewably. Dirt can be provided through farming loops, Polluted Water can come from toilets and other wastewater sources, and Phosphorite is commonly supplied through Drecko ranching. Because the building's inputs are all compatible with ranching and plumbing systems, it fits well into self-sustaining colonies. The produced Fertilizer can also be cooked into Dirt, which makes the building part of a possible renewable Dirt loop as well.

A notable byproduct is Natural Gas. The gas output can be burned for about 88 W of power and can also refund some of the Polluted Water cost through energy use. In practice, the gas output is large enough to support a Gas Range for a little more than one meal per cycle, and higher cooking skill reduces the time spent cooking, which further improves the effective return.

A few practical notes make the building easier to use:

• The Fertilizer Synthesizer outputs at a temperature above its overheat temperature, so its products should be removed quickly, or the building should be made from Gold Amalgam and cooled regularly.
• Placing it in a Carbon Dioxide pit makes Natural Gas collection easier, since the gas rises upward. However, dupes collecting Fertilizer will need to hold their breath there, and the Natural Gas layer can cause Eye Irritation.
• Germs in Polluted Water are not destroyed; they are transferred to the produced Fertilizer.
• Because the total heat capacity of the inputs is greater than the total heat capacity of the outputs, the building can destroy heat if fed warm enough ingredients. Hot Polluted Water is the most practical way to exploit this, since heating solids is inconvenient.
• A reservoir of warm Polluted Water can be routed through the building after being used for cooling, letting the Synthesizer delete some of that heat while also producing Fertilizer.

Overall, the Fertilizer Synthesizer is a compact conversion building that trades basic colony byproducts for a strong farming resource, with useful gas and heat side effects if it is integrated into the right infrastructure.