Nutrition A Simple Key for Diagnosing Nutrient Deficiencies in Aquaponic Systems: Many plants fail to thrive in aquaponic systems- often due to pests and diseases, lack of sunlight, improper care and environment, and nutrient deficiencies. Excluding all of these other possibilities, nutrient deficiencies in aquaponic systems are not too difficult to diagnose (most of the time!). In aquaponic systems, there are five deficiencies that typically occur at some point: Nitrogen, Iron, Potassium, Magnesium, and Calcium. Here is a simple key to help you figure out what the problem is, and how to treat it. 1.Is your plant Chlorotic? (Is there yellowing of the leaves?) If yes, see 1a, if no, go to 2 a.Is the yellowing only between the veins, with the veins remaining green? Is the young growth most affected? If yes, then you most likely have an Iron deficiency. If no, go to 1b. b.Is the yellowing across the entire leaf (veins included)? Does the old growth appear to be more affected than the young growth? If yes then you likely have a Nitrogen deficiency. If no, go to 1c. c.Is the yellowing primarily between the leaf veins, but the old growth is most affected? Are the plant leaves cupping, developing brown spots, or dry and dead edges? Are the roots not developing? Is there some chlorosis developing around the edge of the leaf in older leaves? If yes, then you likely have a Potassium deficiency. If no, see 1d. d.Is the yellowing primarily between leaf veins, but the chlorosis is concentrated in older leaves, with the most affected leaves falling off (old chlorotic leaves falling off). If there is little burning along the leaf edges or dead, brown spots on the leaves and the old, chlorotic leaves fall off, then you likely have a Magnesium deficiency. 2.Are there necrotic spots (dead, brown spots) on the leaves or stems of the young, rapidly growing parts of the plant? Are there brown dead spots on the fruit (especially on the blossom end)? If so, you likely have a Calcium deficiency. If no, then you may have another nutrient deficiency, but it is not as likely as other variables, including temperature, pests, and cultural methods. How to treat these deficiencies: Iron: Add chelated iron to your system - there are many types out there, but FeEDDHA and FeDTPA are the best types of chelated iron. (FeEDDHA will turn your water red though.) There is quite a bit of math involved in determining how much to add, because different chelated iron types have different purities. Basically, you want to add 2 mg of pure iron per liter of system volume every 3-4 weeks. Nitrogen: You should know that this is a possibility if you havent been feeding much, have too much vegetation to fish, or have been measuring low nitrate levels in your system. Switch to a higher protein feed and feed more often to correct. If this doesnt correct, remove some plants and look for straw, wood or another high carbon substance in your system that could be consuming nitrogen in decomposition. Remove all wood, straw, etc. Potassium: In systems with low pH, add potassium hydroxide (caustic lye) to raise pH and supplement potassium. In systems with neutral or high pH, add kelp meal concentrate (0-0-10) or potassium sulfate (0-0-50) in very low quantities. Magnesium: In systems with low pH, adding dolomitic lime can help, as well as hydrated lime. In all systems, Epsom salts (magnesium sulfate) can be added in small quantities to supplement magnesium. Calcium: Most systems have plenty of calcium because its common in the water. However, if theres too much potassium in the system, your plants might show a calcium deficiency. To correct in low pH systems, reduce the amount of potassium you are supplementing and add hydrated lime to the system in small quantites. In neutral or high pH systems, the best way to supplement calcium is with small amounts of calcium chloride. Remember that correcting deficiencies takes time- often 2-3 weeks, so add small amounts and wait to see the results. Adding too much of any of these substances can cause bigger problems than a nutrient deficiency! :-)
Posted on: Sun, 21 Sep 2014 04:52:06 +0000
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