Nutrient management is one of the vital components of a successful hydroponic garden. Lacey Macri and Roy O’Mahony explain how basic supply and demand principles apply to successful nutrient management programs, and share some emerging technologies to help hobby growers determine the needs of their plants.
Growing hydroponically in a controlled environment requires a lot of equipment, time and effort. Many hydroponic growers have got everything dialed in, including their lighting, temperature, humidity, water quality and, to a certain extent, plant nutrition. While some controls have become technologically advanced, others have remained rather antiquated for the times and tend to be underestimated as a result.
Nutrient management has long been a complicated matter, and the technology has thus far been limited, with labs being the primary go-to for testing nutrient levels. If growers owned their own “lab-to-hand” equipment, it would be possible to test more samples in real-time. This would also lead to more data, better decision-making and, for the first time, the opportunity to manage nutrients at a precise level. If in doubt, the growers could repeat immediately, and the price for sampling and analyzing would be more cost-effective. While access to this kind of technology has so far been limited for hobby gardeners, some unique technologies recently introduced in to the commercial hydroponics sector may soon be available to home growers. However, before taking advantage of these new tools, it is important to understand the relevance of nutrient management.
Many growers quickly learn how important nutrients are for their plants to flourish, but what are we doing to optimize the feed schedule? The synchronization of the supply and demand of plants is critical, as it will increase nutrient and water use efficiency, and save growers money. TDS (total dissolved solids) and EC (electrical conductivity) meters have so far been the standard tools for growers. Ion-selective electrode sensors are a more recent option. An ISE sensor measures the potential of a specific ion in solution. The pH electrode, for example, is an ISE for the hydrogen ion. This potential is measured against a stable reference electrode of constant potential. The potential difference between the two electrodes will depend on the activity of the specific ion in solution.
This activity is related to the concentration of that specific ion, allowing the user to make an analytical measurement of that specific ion. Several ISEs were recently developed for a variety of different ions that have reduced the maintenance costs typically associated with ISE meters.
Monitoring and Fine-tuning
While the data that TDS and EC meters provide may still be important to monitor in many circumstances, ISE technology has brought nutrient management to a whole new level. Because ISEs make it possible to measure individual ions, growers are able to fine-tune their nutrition programs. This opens the door to greater sustainability in the sense that if growers are able to monitor and supply only the nutrients plants need, they will produce less waste and save resources. In many instances, different strains of the same crop may have different nutrient demands. It is important to use high-quality nutrients that are geared specially for crop type and growth phase. For common crops, there is a lot of information and research available to help novice growers provide their crops with what they need, when they need it.
Monitoring nutrient levels is vital because even with a nutrient program geared to crop type and growth phase, imbalances can occur. A plant will often display visible symptoms of nutrient imbalances, but many of these issues produce visually similar symptoms, so it may be difficult to make an accurate diagnosis with the naked eye. This very situation is what leads many growers down the path to plant destruction. Improperly diagnosing nutrient imbalances can have devastating results that might easily have been fixed otherwise. “Hidden hunger” is a condition in which plants do not display any visual symptoms because the deficiencies are relatively minor, but these minute imperfections can lead to a 10-15% loss in crop yield quantity and quality.
Another common example is confusing one deficiency with another, based on visual symptoms. It is difficult to use visible symptoms to accurately identify which nutrient is deficient. Nutrient deficiency symptoms should be confirmed with feed analysis. One example of this difficulty is distinguishing between nitrogen and sulfur deficiencies in crops. Nutrient analysis may confirm a suspected nutrient deficiency or it may indicate that another nutrient is the problem. One example is an incorrect calcium-to-potassium ratio, which leads to poor calcium uptake and results in blossom-end rot, vastly reducing crop quality.
As with any investment, peace of mind will always hold a certain value when it comes to protecting that investment. What’s the good in investing your hard-earned cash and effort into something that’s out of your control? While starting with a high-quality nutrition program is imperative to the success of your crops, that isn’t where the investment ends. To take advantage of all the benefits of your high-end plant food, it’s important to monitor your plants’ needs regularly, and adjust according to the data you’ve gathered.