Until recently, scientists did not consider nickel an essential mineral for plant growth. Now, however, nickel is recognized as an essential nanonutrient (a nutrient needed in particularly small quantities).
So what makes nickel necessary to plants? For starters, seeds cannot germinate without nickel. Furthermore, plants use nickel to produce the enzyme urease. Urease is generally known as the enzyme needed to absorb urea fertilizer, but plants also use it to absorb iron.
Finally, nickel helps promote the health of beneficial bacteria and fungi in the soil.
Nickel is fairly common throughout the environment. It can be found in soil, water, animal manure, and the remains of plants that accumulate nickel readily, such as brassicas.
Nickel deficiency is fairly uncommon in plants, both because the mineral is so common and because plants need so little of it. Plants most likely to suffer from nickel deficiency include legumes, peaches, plums, and pecans.
When a nickel deficiency does occur, it is typically because some other type of imbalance in the soil is preventing the plant from taking up enough nickel. High pH is one reason that this can happen, as is contamination of the soil with cadmium. Excess levels of cobalt, copper, iron, magnesium, or zinc can also interfere with uptake. However, keep in mind that some soils may truly become nickel deficient, particularly sandy or gravelly soils.
The symptoms of nickel deficiency in plants are not well known at present. However, the following are some signs that may appear:
- Sparse foliage.
- Small, rounded leaflets (“mouse ears”) in pecans.
- Color loss in new leaves.
- Brittle wood in trees.
- Reduced yield.
- Failure of saved seeds to germinate.
Because application of special high-nickel fertilizers can cause serious toxicity problems, it is usually best to find a fertilizer that offers a good mix of trace elements to correct the problem. Consider one of the natural sources of nickel listed above. Also be sure to correct any other soil pH or nutrient imbalances that may be interfering with uptake.
Nickel toxicity can result from use of either contaminated water or fertilizers containing nickel.
- Poor shoot growth.
- Pale leaves.
- Leaf death.
- Poor root growth.
- Deformed flowers.
Of course, when dealing with nickel toxicity, addressing the source of the problem is the first step to take. Also, adding organic matter to the soil may help reduce the rate at which plants take up the mineral.