When it comes to sizing an iAVs, the first thing you have to know is how much fruit and vegetables you are going to need. The next thing to know is the quantity of fruit and vegetables you can grow in a given space.
Working out how much food you need is a simple matter of tracking your usage over a period of weeks – and then annualising the numbers.
Since iAVs is essentially about horticulture (the fish are simply the means to the end), your first task is to calculate the amount of food that you need to supply your kitchen or feed your village – and then design the fish production to suit that growing area.
For the purposes of sizing an iAVs, we suggest you base your calculations on tomatoes. They are a high-value crop which is very demanding of nutrients. In cultural terms, if you can grow tomatoes successfully, you can pretty much grow anything.
Four indeterminate single-stem vine tomato plants may be accommodated in a square metre of iAVs bed. Use the same spacing for single-stem vining cucumbers and bell peppers. Cayenne and jalapeño peppers can be spaced 6 to 8 per m2 depending on variety, Greens and Brassica species spaced as with high-density or raised-bed gardening – typically 12″ (300mm) in-row x 18″ (450mm) between rows for 6 to 8 /m2.
For backyard purposes, if you use typical spacing for climbing legume crops, you’ll have plenty of space to intercrop lettuce and other leaf crops between rows. As legumes, beans source their nitrogen from the air, so intercropping with heavy nitrogen feeders like Swiss chard, salad greens and Asian greens makes good sense. Climbing legumes are generally spaced 6″ to 8″ (150 – 200mm) in-row and 30″ to 36″ (750 – 900mm) between rows
Now, every species (and every cultivar) has its own nutrient and space (and every other kind of) requirement, so our suggestions are merely a guide to system sizing. Specific spacing and nutrient information is freely available on dozens of gardening web sites. Typically, however, you could anticipate iAVs to yield 130 to 150% more than traditional garden practices.
Each 1.0kg of fish weight gain provided sufficient quantities of all required plant nutrients to sustain 2 tomato plants yielding 5-7kg of fruit per plant over 3 [to 4] months depending on cultivar and climate.
For example, if you started out with ten 10g fish and you grew each of them to 110g – a total of 1100g – you have sufficient nutrient to produce 10 – 14kg of tomatoes in three months.
The goal should be to run sufficient fish biomass to support a given number of plants…..not the other way round.
Note: The figures used in this article assume the specifications and conditions experienced during the Ratio studies. As such they are indicative – to assist your planning efforts. Your results will differ (for better or worse) according to your circumstances.
It is very difficult to generalise about the relative nutrient demands of various crops. When compared to indeterminate tomato – at 4/m2 – the following is a reasonable expectation:
- Eggplant, melons (trellised) in range of 60-70% /m2 of the requirement of tomato
- Cucumber, peppers and Brassica (cole) spp. approximately 40 to 60% /m2
- Squashes and gourds (trellised) at 40 – 60% /m2
- Beans and peas (except for N) approximately 30 to 50% /m2
- Beets, chard, kale, spinach, in to 20 to 30% range /m2
- Lettuce (bibb, cos, leaf) in the 10 to 20% range (also dominantly N) – or less
- Basil, rosemary, thyme and other culinary herbs ~ 10%
- Chives, dill, radish – < 5%
If your enthusiasm doesn’t extend to all of this work, you might want to take a look at The Carpark Model:
iAVs has the capacity to produce fish and fresh vegetables sufficient to provide a family with 200 kg of fish and 1,400 kg of vegetables (fruit) per year in a footprint equal to an automobile parking space. *
*Assumes a sub-tropical or temperate climate or controlled environment that will permit year-round plant production.
Practicing crop rotation (different families) is recommended, as it is for any garden or field.
- Focus on tropical species in summer months (tomato, pepper, melon, summer squash)
- Spring/Fall crops include beans, greens, herbs, okra, winter squash(es)
- Winter crops (GH), snow/sugar peas, Brassica spp., some greens