In the fourth episode of #GrowEasyChat, our Farm Operations Manager (Rachael Warner) answers questions about the use of organic and inorganic nutrients in hydroponic systems.

Q1. Are crops grown in a hydroponic system as nutritious as those grown in the field?

A1. Hydroponics can produce high quality, nutritious crops. All essential nutrients plants require are supplied by the air or nutrient solution. So, although there is no soil, the plants have everything they need to grow and produce the healthy compounds, such as vitamins, we appreciate them for.

Q2. What are the benefits and disadvantages of using inorganic nutrient salts in commercial hydroponic systems?

A2. Inorganic nutrients offer ease of use and high levels of control over nutrients. The nutrients are in highly bioavailable forms, meaning plants can easily and efficiently take them up via their roots. It is possible to work with these nutrients in mixes or in more pure element or compound forms. This allows growers to respond to crop specific needs by using water analysis or ion selective electrodes (ISEs). Unfortunately, these fertilizers are generally very resource and energy intensive to produce, reducing the overall sustainability of hydroponic growing.

Q3. What are the benefits and disadvantages of using organic nutrients in commercial hydroponic systems?

A3. Organic hydroponic nutrients come from a variety of primarily plant based sources. These offer the advantage of increasing the overall sustainability of hydroponic farming. These are not used as widely used in commercial production, as they are generally harder to work with and provide inconsistent results. In organic fertilizers, the essential nutrients plants require are bound in organic compounds, which must be broken down by microorganisms before they can be taken up by plants.

Q4. What factors should be considered when deciding between organic and inorganic fertilizers?

A4. Overall, organic hydroponic fertilizers are harder to work with and have less resources available. It is not advisable for inexperienced growers to work with organic nutrients. Experience growing with synthetic fertilizers provides a foundation of knowledge to help troubleshoot issues as they arise. Additionally, the water source can have a large impact on the stability of the pH in organic systems. Typically there is not extensive input for pH control, rather a stability is found with time. Usually higher alkalinity will provide more buffering capacity, although there is not a hard rule around this.

Q5. What are ion selective electrodes (ISEs), and what is the benefit of using them in managing a nutrient solution?

A5. Ion selective electrodes (ISEs) are sensors which measure the activity of a specific ion in solution, allowing the user to infer the concentration. Electrical conductivity (EC) is an important measure for managing hydroponic nutrient solution, which gives the overall abundance of ions in solution as conductivity. ISEs provide an advantage by providing the concentration of an ion in real time, rather than having to send out water samples for analysis. This can allow for highly controlled nutrient composition in systems, reducing the overall inputs and maximizing the crop health. ISE technology is not yet widely applied commercially, as the systems are expensive and the tech is still being improved.

Q6. How does the effective delivery of nutrients contribute to the overall sustainability of hydroponic food production?

A6. Resource use efficiency is a key in monitoring the overall sustainability of a farm. It is important to minimize inputs, while maximizing outputs. Good nutrient management ensures the inputs and waste are reduced. This contributes to a reduction in the energy and material footprint over the plant production life cycle.