Mar 14, 2024
Image Source: https://link.springer.com/article/10.1007/s42853-023-00182-0
March 13, 2024
Roland Sier
The Importance of Nutrient Management in Controlled Environment Agriculture
Controlled Environment Agriculture (CEA) is a technology-based approach toward food production, which aims to optimize plant growth and productivity. CEA systems can include greenhouses, vertical farms, indoor farms, and other structures that provide precise control over the growing environment.
In Agriculture and Controlled Environment Agriculture (CEA), particularly within vertical indoor farming, optimization is the key to unlocking profits and let’s be honest, continuance of business. Considerable investments have been poured into sophisticated automation systems, LED technology and HVAC systems - undoubtedly critical components. Yet, one crucial element often remains overlooked: nutrient solution management.
Nutrient management in CEA involves the careful monitoring and adjustment of nutrient solutions to meet the specific needs of different plant species. Key nutrients required by plants include macronutrients (nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur) and micronutrients (iron, manganese, zinc, copper, molybdenum, and boron).
In CEA and hydroponics, the benefits, besides a pesticide-free cultivation, are evident: water recycling, astonishing plant density and unparalleled control over nutrients, yield and cultivation time. Controlled environment agriculture (CEA) can increase crop yields by up to 20 times compared to traditional farming methods. But do farms truly harness these advantages to their fullest potential?
More often than not, the answer is simply no, based on my own experience and research. Many farms encounter diminishing yields over time due to inadequate or neglectful nutrient management - a fundamental oversight with significant consequences.
In this article, I'll focus on the pivotal aspects of EC and nutrient balance, as they hold the key to unlocking enhanced yield and quality.
Recycling in hydroponics: Unveiling a "self-dysregulating" system
Imagine preparing a fresh batch of nutrient solution for your operation. Initially, all seems promising - the recipe, best case tailored to your crops' needs, with spot-on EC and pH levels. Initial yields soar. However, over time, a gradual decline in yield sets in. Despite optimal conditions in other areas like light and temperature - yields plummet. The decline in yield continues and suddenly yellowing leaves start to pop up. Have you encountered this issue?
Often values like the EC still look fine, but this is where the “danger” of the EC value lies
While EC indicates the presence of salts (fertilizer) in the nutrient solution, it fails to specify precisely which nutrient(s) are present. Natural accumulation and depletion of specific nutrients constantly alter the nutrient ratio, which is an inevitable process in all systems.
But is dumping the water and starting fresh the solution to this issue? Far from it! Dumping nutrient solutions in my view is a fundamental error in management, squandering precious resources. It’s literally throwing money down the drain.
Nutrient management in Agriculture and Controlled Environment Agriculture (CEA) is critical because it directly influences the health and productivity of crops. CEA, relies heavily on the precise control of nutrients. Without proper nutrient management, plants may not receive the necessary elements they need to grow, which can lead to stunted growth, poor yield, and even plant death in extreme cases. Another reason nutrient management is important in CEA is because it allows for the optimization of resource use. In traditional agriculture, a significant amount of nutrients can be lost through leaching or runoff. However, in CEA, nutrients are delivered directly to the plant roots in a controlled manner, reducing waste and improving efficiency. This not only saves resources but also reduces the environmental impact.
Visualizing changes in the nutrient solution over time
An illustration from "Plant Factory: An Indoor Vertical Farming System for Efficient Quality Food Production" illustrates nutrient concentration changes over time, while the EC is kept steady at a fixed set point. This is what we need to understand (which many farms don’t): The dosing of the fertilizer is automated and set to a specific target EC value. Sulfate (SO4²-) concentration highlights the issue of accumulation over time in this image and provides a great example.
Source: Plant Factory An Indoor Vertical Farming System for Efficient Quality Food Production, Second Edition, Toyoki Kozai et al. Figure 20.2.; Changes in ionic concentration of the recirculated nutrient solutions controlled at a fixed EC (an example for lettuce)
In this experimental configuration, sulfate concentrations exceeded those of the two most crucial nutrients for plant growth: Nitrogen (represented here as NO3-) and potassium (K+). This imbalance significantly reduces yield! Remarkably, this phenomenon isn't limited to controlled experiments. It mirrors real-world observations in farms lacking effective nutrient solution management worldwide.
An interesting side note: This experiment does not account for sodium (Na+) levels. Depending on the fertilizers used, sodium input and its accumulation can be significant over time. It's essential to monitor these levels closely to ensure optimal nutrient balance and avoid potential issues associated with sodium buildup, such as unwanted or excessive input from disinfectants like hypochlorous acid, which can even be produced on-site.
Regular water analysis: A crucial step
Do you routinely test water samples? There are two types of farms, I’ve seen:
- Farms that take weekly samples and often hoard data without taking action
- Farms that barely test at all, maybe two times a year and are not really aware of any values, like their tap water or nutrient solution (because EC says it’s “great”).
Missed opportunities in both cases!
Regular analysis is extremely important. Utilizing this data allows for recipe adjustments, counteracting depletion and accumulation effects.
In some cases the water analysis can even show you how effective the cleaning team in your farm is working ;)
Achieving record-breaking results - an impressive example
Maintaining a tailor-made nutrient solution at optimal nutrient levels, without any depletion and accumulation, is key! This can lead to an increased yield “by an astounding 63% (!) [...] and even shortening the days after transplant from 21-22 days, down to 17-19 days”, says Erik Lundgren, Co-founder and Chief Research & Development Officer at Ljusgarda, now called Supernormal Greens.
This realization came after getting help from a nutrient expert and starting to adapt their nutrient solution on a regular basis. The increase of 63% in yield was enormous and even the overall quality of the plants improved too! Supernormal Greens now update their nutrient solution with every water analysis to maintain perfect nutrient levels.
In conclusion, the true potential of CEA lies not solely in technological advancements, like fine tuning HVAC or light systems, but also in mastering the art of nutrient solution management. By prioritizing this often overlooked aspect, farms can unlock unprecedented growth while conserving precious resources, like fertilizer and water. It's a win-win scenario - a testament to the symbiotic relationship between technology and nature in modern (indoor) agriculture.
Roland Sier, M.Sc.
Nutrient solution expert for tailor-made nutrient solutions and nutrient solution management