One of the many benefits of growing in hydroponic systems is the grower controls all the inputs . This means the quality and volume of nutrients the grower wants will go into the system . The downside is there is no help from Mother Nature . It is then totally on the grower to make sure they don ’ t get too much of a good thing and the hydroponic system becomes a toxic soup of too many nutrients for your plants . Like so many well-meaning , young goldfish owners who overfeed their pet to death , it ’ s possible to feed your plants in a hydroponic system to death as well . There is a lot of available information about nutrient deficiencies in crop production , but not as much information is available about toxicities . To correct or prevent nutrient toxicity in plants , we must first know what it is and how to identify it .
Identifying Nutrient Toxicity
Not all plants present symptoms of toxicity and not all show it in the same ways . There are , however , many similarities and some assumptions can be made to at least indicate there is a toxicity issue . It is , though , incredibly important to be able to distinguish between deficiency and toxicity symptoms . When one or more nutrients are present in a hydroponic system in abundance , it can impede the proper absorption and utilization of other elements even if they , too , are present in sufficient amounts . The nutrient or nutrients in excess will block the other nutrients . The cure for deficiencies will almost certainly cause further harm in plants experiencing toxicities , so positive identification is the first step to addressing any toxicity issues in your hydroponic system . Let ’ s check out some of the most common toxicities and what they look like in hydroponic crops .
Macronutrient Toxicity Symptoms :
Nitrogen ( N ) — This is often the nutrient most likely to be found in toxic amounts , especially for newer hydroponic growers . Nitrogen toxicity can present in several possible ways . Leaves may be lighter green in color than normal , especially older , lower leaves . The plant stalks may be shorter than normal and slenderer than expected . Flower heads may not fully form or may not form at all , and root systems may be exceedingly dense . In extreme cases of N toxicity , stems may become stiff and brittle .
Phosphorus ( P ) — Plants with excessive amounts of phosphorus can be difficult to diagnose as there are not always specific symptoms to identify . Phosphorus toxicity is somewhat rare and generally will present as copper ( Cu ) or zinc ( Zn ) deficiencies as too much P will impede the absorption of copper and zinc . Some symptoms may include stunted and abnormally green plants and / or purple pigmentation on the undersides of leaves . Potassium ( K ) — Potassium toxicity will generally present as an overall weaker plant . Growth will be stunted and leaves will be smaller than normal . Chlorosis may be noted at the leaf tips and veins and / or edges of the leaves may be purple . These symptoms generally appear on lower , older leaves first . Like phosphorus toxicity , potassium toxicity is not usually seen . Too much K can interfere with the uptake of several secondary macro- and micronutrients . This then can appear as deficiencies in nutrients such as magnesium , manganese , iron , and zinc .
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Positive identification is the first step to addressing any toxicity issues in your hydroponic system .”
Secondary Macronutrient Toxicity Symptoms :
Calcium ( Ca ) — Toxicity with calcium can be difficult to identify . Too much of it will block potassium and manganese absorption so it is easier to spot calcium toxicity as a deficiency in the other two nutrients . Plants with too much Ca will often be severely stunted . Leaves may be more crinkled or form a rosette . Older leaves may have interveinal white spots near their margins and may curl downwards . Chlorosis and then necrosis ( cellular or tissue death ) will appear at leaf margins too . The growth pattern of the whole plant will be more horizontal overall .
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