In aquaponics, the main advantage is the ability to gather the most delectable and fresh ingredients right when you need them for your next meal. However, if you desire the most flavorful and nutritious ingredients, it is important to ensure that your plants receive proper nourishment. To achieve this, it is essential to prevent nutrient deficiency in aquaponics systems.
Aquaponics offers a simpler way to optimize the diet of your plants compared to soil gardening and requires less maintenance than hydroponic methods. The natural processes in aquaponics will take care of most of the work for you, as the majority of nutrients your plants need will come from the fish feed. Additionally, occasionally supplementing your fish’s diet with natural food like insects or worms is beneficial. However, if your plants lack certain elements or receive excessive amounts of others, they will indicate it to you if you know how to interpret their signals.
Why even bother?
Plants that lack essential nutrients or have an excess of unhealthy nutrients are more susceptible to insect attacks due to their weakened defensive state. The comparison can be made with a situation where a person is both intoxicated and malnourished, making it difficult to fend off a swarm of locusts. In a similar way, plants that are not receiving a well-balanced diet will have diminished productivity, compromised health, and less desirable taste. Just like humans, plants also need a diverse range of nutrients. When a plant lacks certain nutrients or consumes excessive amounts of others, it will suffer negative consequences. For instance, consuming only French fries would likely make a person sick, while feeding fish a diet solely consisting of French fries would also have detrimental effects on plants. This includes stunted growth, leaves with unusual colors, low production, and potential death of plant parts – all indications of an unhealthy diet.
How can I tell if my plants are deficient in something?
When we talk about the word ‘nutrient,’ we are referring to the elements that plants consume. This group of elements includes nitrogen, potassium, phosphorus, magnesium, iron, and calcium. To determine if a plant lacks any of these elements, we can categorize them into two groups: ‘mobile’ and ‘immobile.’
Mobile nutrients are nutrients that move within the plant. They transfer from older leaves to newer leaves in order to support growth. When a plant lacks a mobile nutrient, the initial signs of deficiency will appear in the older leaves. This happens because the nutrient is transported to the location where new leaves are forming and is not replenished in the older leaves.
Nutrients unable to relocate: Once utilized in plant growth, these nutrients become immobile. Consequently, when a plant is deficient, the initial signs will manifest in the newer leaves primarily. The older leaves retain their immobile nutrients, while the new leaves lack an adequate supply.
Two common issues in Aquaponics
If your plants are displaying these symptoms, it is likely that your system lacks sufficient iron supply through fish food. In such cases, supplementing your system with iron chelate may be necessary.
When considering the presence of iron, it is essential to note that even if there is an ample amount of iron in your system, it is possible for your plants to not absorb it effectively due to elevated pH levels. If the pH level is significantly higher than 7.0, your plants will face difficulties in efficiently consuming the iron. Hence, it is advisable to strive for a pH of 6.8 in your system as it provides a suitable balance for the fish, bacteria, plants, and the absorption of iron by those plants, resulting in a smooth functioning of everything.
An additional problem that can occur in aquaponics is nitrogen toxicity, which can be compared to plants being lazy and overeating. A clear indication of this problem is when the leaves turn from a vibrant green to a dark shade, potentially affecting the fruiting process. The solution is to reduce the amount of food provided to these plants. This issue may be caused by an excessive amount of fish producing more nitrogen than the plants can handle, or a shortage of plants or grow bed space to effectively eliminate nitrogen from the system. The best approach would be to introduce more plants and refrain from feeding the fish for a few days. Additionally, it could be an enjoyable idea to cook some fish tacos on the barbecue.
It can be tricky to pick
Insects, disease, pH, water quality, and transplanting stress are among the various factors that can cause plants to exhibit symptoms resembling nutrient issues. Therefore, it is important to thoroughly examine your entire system if your plants are struggling. The uptake of certain nutrients by some plants can be affected by a high or low pH, so the problem may not be a lack of nutrients in the system, but rather an issue with the pH level affecting the plants’ hunger. Therefore, it is advisable to check the pH. Additionally, plants can experience multiple nutrient deficiencies or toxicities simultaneously, leading to increased difficulty in identifying the issue. Insects and diseases can also be mistaken for nutrient problems, but they often arise as a result of a deficiency in the first place. This makes the situation even more challenging.
If you want the best food, ensure that you feed it properly. Although it may appear complex, take comfort in the fact that aquaponics is an uncomplicated method to cultivate plants with a balanced nutrient content, and approach any problems like a mystery to solve. Nature is remarkable and will provide you with delicious food as a reward if you give her occasional care and attention.
Common plant deficiencies
As much as we hope for a problem-free experience as aquaponics farmers, we still encounter daily challenges. Similar to any farming method, it is crucial to regularly inspect plants for lacking nutrients.
In an aquaponic system, it is crucial to ensure that all the treatments we recommend for plant deficiencies are completely safe remedies. This is because we cannot introduce any ingredients that may potentially harm the fish or disturb the system’s balance.
Nitrogen deficiency or toxicity can be understood by considering each step of the thinking process, without adding or removing any information.
Despite the nitrogen contribution from the fish, a nitrogen deficiency can still occur. This deficiency is indicated by the yellowing of the tips and center vein of the lower leaves. Conversely, excessive nitrogen levels can lead to a nitrogen toxicity problem. In such cases, the leaves will become intensely green or even black, and this might disrupt the fruiting process.
Make sure the ratio of plants to fish in your system is correct.
Phosphorus lack
It is common for phosphorous deficiencies to become noticeable in the older leaves of the plant, typically found at the lower part. Therefore, it is important to examine the lower leaves for signs such as an intense dark green color with red or purple borders. Plants experiencing phosphorous deficiencies are generally smaller in size and exhibit stunted or sluggish growth rates.
Our preferred method of addressing phosphorous deficiencies involves adding mineralized waste to the system once a week.
A lack of potassium
Potassium serves as a regulatory chemical for facilitating cellular water movement. The initial indication of insufficient potassium is the development of yellow areas on the tips and edges of new leaves.
To solve the problem, it involves burying banana peels in the media located at the plant’s base.
Iron deficiency is a condition characterized by a lack of iron.
Iron is one of the most common supplemented nutrients in an aquaponics system. The leaves become yellow and have small green veins in older leaves while younger leaves seem to look bleached.
Before supplementing, it is important to check the pH of your system. Typically, we employ an iron chelate form when supplementing with iron, which can be classified into three different types.
- FeEDTA – can be slightly toxic so make sure to use it in moderation. This form of iron can only be available to plants if your pH is below 6.5.
- FeDTPA – Only available to plants if the pH is below 7.5.
- FeEDDHA – This form works well up to a pH of 9 but just note that it does change your water to a red color.
Deficiency of magnesium.
Typically, magnesium and iron deficiencies are commonly found together in plants. When magnesium levels are low, the leaves begin to lose color in the areas between the veins, while the veins themselves remain green. Generally, the initial symptoms of deficiency are observed in the older leaves.
Calcium deficiency refers to a condition in which there is a lack of calcium in the body.
First, a calcium deficiency is likely to manifest in the roots, shoots, and younger leaves, resulting in their deformation.
Our approach to addressing calcium deficiencies involves adding calcium nitrate to the system using the dosing buckets.
Zinc deficiency refers to the condition when there is an insufficient amount of zinc in the body.
Zinc, being an immobile micronutrient, causes deficiency symptoms to appear on the new leaves of a plant. It is worth emphasizing that zinc deficiencies are uncommon due to the minimal amount of zinc required by plants. Nevertheless, when a plant lacks zinc, one can observe light discoloration of the leaves between the veins.
To address zinc deficiencies, we administer a foliar application of zinc EDTA at a concentration of 1g per liter of water. To proactively prevent zinc deficiencies, the recommended approach is a monthly foliar spray of Seabrix, at a rate of 3ml per 1 liter of water. This spray provides trace amounts of zinc that are anticipated to meet the plants’ needs.
A shortage of sunlight.
Plants have varying sunlight needs. Insufficient sunlight results in leaves appearing faded and drooping.
In order to ensure that the plants receive sufficient light, attempt to relocate them. Additionally, during the planting stage, strategically arrange the beds and DWCs to guarantee that all plants are in the best possible position.
