This roundtable was originally published June 26, 2015.
About the Upstart Farmers Roundtables
Upstart Farmers Roundtables are an informal, biweekly event. Using Google Hangouts video calling, a small group of Upstart Farmers comes together to share their experiences and learn from each other. Each week is guided by a discussion topic, with growers welcome to ask their own questions.
Roundtables are exclusively for Upstart Farmers, and recordings are only released to the Upstart Farmers Community.
Roundtable: The Root Zone
Why is the root zone an important topic for Upstart Farmers?
Often times farmers forget about the root zone and what happens below the soil surface or the media surface, or think it’s not as important. It’s important to understand how plants work, where they are vulnerable, and try to discuss what happens beneath the surface, even when you are using a media-based growing method. Understanding what the root zone represents in terms of productivity is extremely valuable for Upstart Farmers.
What important processes are occurring in the root zone that Upstart Farmers should be considering?
If you’re an aquaponics grower, you have all sorts of gas exchange going on with dozens of different gasses, acidification of your solution, nitrification, CO2 fixation, oxygen consumption, CO2 release, etc., all of which are core to plant production. Hydroponic growers have many of these same processes occuring in the root zone as well.
The root zone in aggregate media types
These important processes were one of the first big considerations when designing the ZipGrow towers and their Matrix Media. More plant issues occur in the root zone than they do on the media surface. Unfortunately, a lot of issues can arise in the root zone when growing hydroponically or aquaponically if using aggregate media types.
Speaking from experience, Dr. Nate explained how other systems like aeroponics and raft beds are subject to things like drastic temperature swings, low DO levels, and solids build-up in the root zone which are very hard to control. These issues can cause rapid root die off.
Designing ZipGrow towers with the root zone in mind
When switching from aggregate media to a fibrous media, like the Matrix Media in ZipGrow towers, you eliminate many common problems with low biological surface area, system clogging, anerobic root zones, and undesirable percolation rates.
The Matrix Media and ZipGrow towers were designed to allow for:
- good filtration,
- temperature stabilization,
- root insulation,
- ideal percolation rates,
- strong anchoring,
- great air exchange,
- high biological surface area,
and perhaps most importantly, to be a great habitat for microbes.
Anaerobic root zones
Anaerobic root zones are bad, bad, bad! They occur when a plant is competing with too much aerobic bacteria and does not have enough access to oxygen from the environment provided in the media. Excessive organic material and poor gas exchange contributes to this problem. If your root zones go anaerobic, you will see rapid root die off and will have a hard time recovering your system.
During the day, plants produce oxygen during photosynthesis. During the night, the plants consume oxygen. Now often times, plants have enough oxygen stored up to consume in the event that they do not have enough available to them. However, plants still need oxygen in their root environment to survive, with the reason being that plants are actively consuming massive amounts of oxygen in the root zone in order to do all of the plant growth processes.
Good oxygen consumption = good plant growth.
As soon as the root zone goes anaerobic, their roots will begin to turn brown and die back. When you have necrotic, dying tissue in the root zone, the plants become extremely vulnerable to diseases and pathogens.
Preventing anaerobic zones
One of the most vulnerable areas on a plant is the crown (the place where the roots transition into shoots and the vascular tissue switches places within the plant). This area is very delicate and becomes anerobic (and therefore infected) fairly easily under the right conditions – mainly if it is water logged. Keeping the crown dry and in aerobic conditions is extremely important.
ZipGrow tower Matrix Media is mostly air. This allows the diffusion process to happen quickly and keeps the plant watered, but not overly moist.
How can Upstart Farmers encourage root zone health?
Other than preventing root zones from becoming anaerobic, Upstart Farmers can also create healthy root zones with temperature stabilization.
Temperature stabilization is one of the most important factors in root zone health. Although plants are adapted to handle temperature swings, their roots will die if temperature swings are too drastic or occur too rapidly. In soil, there is massive thermal mass which protects the plants from drastic temperature swings. However, when growing in hydroponic systems, you have to take special precautions to ensure a stable temperature in the root zone.
For example, mint is sensitive to hot temperatures, whereas basil grows well in heat. However, you can grow mint well even when it’s ridiculously hot by using a water chiller.