Nickel is a trace micronutrient, the most recent element accepted as essential for higher plants (Brown, Welch and Cary, 1987). Its best-known role is as the metal centre of urease, which splits urea into ammonia and carbon dioxide. Plants need it in amounts so small that impurities in salts and water usually cover the requirement.
In practice
Deficiency is very rare in cannabis. Where it has been seen in other crops, it shows as urea accumulating to toxic levels in leaf tips, causing tip necrosis, especially when urea is the nitrogen source. Most hydro recipes do not add nickel deliberately. Excess nickel is toxic and can induce iron or zinc deficiency, so supplements are not recommended without a reason.
Don't confuse with
- Nutrient burn: tip necrosis from high EC, far more common than Ni-related urea burn.
- Nickel-plated fittings: a possible contamination source rather than a feed.
A micronutrient is an essential element plants need only in trace amounts, below a few mg/L: iron, manganese, zinc, copper, boron, molybdenum, chlorine and nickel.Urea is a 46% nitrogen organic compound that soil enzymes convert to ammonium; it is cheap in field fertilisers but a poor choice for hydroponic cannabis.CO2 enrichment raises carbon dioxide in a sealed grow space from about 420 ppm to roughly 800–1,500 ppm, letting plants use higher light intensities productively.A nutrient deficiency is a shortage of an essential element in the plant tissue, causing characteristic symptoms; the cause is often pH or uptake rather than an empty feed.Zinc (Zn) is a micronutrient needed for auxin production and many enzymes; deficiency gives small, twisted new leaves and shortened internodes.Nutrient burn is browning and crisping of leaf tips, then margins, caused by a root-zone salt concentration (EC) higher than the plant can handle.EC (electrical conductivity) measures how well a solution conducts electricity, a proxy for total dissolved salts; growers read it in mS/cm to gauge nutrient strength.Nitrogen (N) is the macronutrient plants use most, built into proteins, chlorophyll and nucleic acids; it drives leaf and stem growth and is fully mobile.Nutrient toxicity is damage from an excess of an element in the plant, either directly or by blocking uptake of others; boron, manganese, copper and chloride are common culprits.
