Choose crops for a recirculating growing system

Recirculating water can be useful, but the crop still needs light, nutrients, space and care. Choose a crop to fit the system you can maintain. Start by distinguishing aquaponics, which includes fish and biological treatment, from hydroponics supplied with a formulated nutrient solution.

Define the product and scale

Are you producing household salad, saleable herbs or kilograms of livestock fodder? Those goals require different quantities and economics. List the expected harvest, growing period and available space. A small demonstration of plant growth does not establish a system’s ability to supply an animal ration.

Match the crop to the system

The FAO manual discusses plant selection alongside fish and water management. Consider root space, support, nutrient demand and temperature. Avoid adding fish feed simply to force plant growth if the fish or treatment system cannot safely accommodate it. Seek advice on any nutrient deficiency.

Measure total inputs

1. Record all replacement water, including cleaning and accidental losses.
2. Record electricity, nutrients or fish feed and daily labour.
3. Weigh usable harvest separately from discarded material.
4. Compare like with like: fresh fodder contains much more water than dry feed.

Test one manageable crop first

Run a small crop through harvest before adding complexity. Keep a backup plan for pump failure and a way to check water conditions. Compare with a sensible soil-grown option if that is the real alternative. The best system may be the one you can keep operating reliably through the difficult season.

Namibian climate and microclimate

Evaporation and plant water use continue even when water recirculates. Hot Namibian conditions, cold nights and power reliability can change the balance. Include shade and protection costs rather than assuming a system shown indoors elsewhere will work unchanged outside.