How we’re tracking what plants eat

There’s no paleo diet for plants growing in greenhouses — and there’s no FitBit or tracker apps for what they’re eating (yet!). Often plants in greenhouses are growing without soil, so how do they get the nutrients they need to grow, and how we do figure out what they’re absorbing?

In hydroponic systems, nutrients are mixed into the water that passes through plant roots. Which elements go into this mix are critical, and maintaining proper ratios of fertilizer compounds is required for the best crop yields. There’s more than just H₂O required to grow a plant:

via the Principles of Plant Nutrition

Grass food.

If you’ve ever picked up a bag of garden soil or fertilizer for your home garden, you may have glanced at a periodic table’s worth of elements and compounds on the bag. For soil, you’ll see a ratio of important elements not gained from the air and water: Nitrogen (N), Phosphate (P), and Potassium (K).

However, with hydroponics we’re not working with soil. Hydroponic growers use premixed nutrient solutions or buy fertilizer in bulk and mix it themselves.

Large industrial growers have entire rooms or areas dedicated to storing fertilizer before it’s mixed into water and fed to the plants:

Fertilizer bags, via Colin on Flickr

Once mixed, there’s typically an “A” and a “B” tank to store the nutrient solution in. There’s a scientific reason for this: the raw fertilizer materials can interact to form insoluble compounds, which would prevent them from dissolving properly into water. To prevent this, different elements are split into separate tanks before mixing them together to create the final solution.

The tanks vary in size depending on the size of the facility — if the facility is on the scale of several acres, the tanks can get pretty big!

via USDA on Flickr

Finally, the solution from both tanks is mixed together and piped out to the plants. In most facilities, the water is recycled and recirculated back to the plants as well. Here’s an example of this happening in an NFT (Nutrient Film Technique) system:

courtesy of Sky Vegetables

How do growers measure what’s being delivered to the plants? There are a few easy things to test for first. pH and EC (Electrical Conductivity) can be read via meters. These readings test for imbalance in the system. To understand nutrient solutions over time, more detailed tests must be done. Growers can send water samples and plant tissue samples to a lab to test for element fluctuations occurring over time. Nutrient solution ratios will change based on the plant growth stage and growing climate.

via Hill Laboratories

Growers need to interpret these results and make changes to the solution if necessary. There’s a gap in time here though: it takes time to get the reading, and even more to adjust the concentrations of fertilizer salts accordingly. Then — how do those changes in nutrients correlate to the final product of the greenhouse: the plants harvested? And how do growers improve the nutrient testing and adjustment cycle?


Google Analytics…for plant nutrients!
Remember those N-P-K Ratios?

This is where Agrilyst comes in. We’ve built a way for growers to track these reports and soon they’ll be able to see how their changes in nutrients directly affect their yield, without having to manually compute it each time or rely on a complicated Excel spreadsheet to calculate it.

Tank readings can be measured and recorded on a daily basis, and we’ve plotted a graph of how each metric changes by day. It’s easy to pick out a spike in a value this way and see how that correlates to changes in your facility.

Plant tissue and nutrient solution analyses from the lab can be recorded as well. We keep track of each of your important measurements over time.


Now you’ve got a crash course in plant nutrition! If you want to get started growing indoors, you won’t have to worry too much about this level of detail — you can buy pre-made nutrient solutions, and then test + adjust your water’s pH on your own for a long time. In commercial greenhouses though, we’re betting this makes a serious impact in how growers can react and learn from the data they’re dealing with on a daily basis. Thanks for reading, and stay tuned to The Greenhouse for more updates from our team!

🌱

Never heard of indoor farming? Want to learn more about how technology and data are changing how we grow food worldwide? We’re always looking for people passionate about this intersection of industries.