Earle E. Cary

Nickel: an essential micronutrient for legumes and possibly all higher plants.

Soybean plants deprived of nickel accumulated toxic concentrations of urea (2.5 percent) in necrotic lesions on their leaflet tips. This occurred regardless of whether the plants were supplied with inorganic nitrogen or were dependent on nitrogen fixation. Nickel deprivation resulted in delayed nodulation and in a reduction of early growth. Addition of nickel (1 microgram per liter) to the nutrient media prevented urea accumulation, necrosis, and growth reductions. This evidence suggests that nickel is essential for soybeans and possibly for higher plants in general.

Beneficial effects of nickel on plant growth

Wheat, barley and oat plants, grown in the absence of added Ni (‐Ni), accumulated 15 to 20 fold higher levels of urea in their leaf tips than Ni supplied plants (+Ni). Oat plants (‐Ni) matured 15 days earlier than +Ni‐oat plants. When grown from low Ni seed, Ni‐deprived barley plants had significantly (30%) lower root and shoot weights than +Ni‐plants and displayed characteristic symptoms that could be eliminated by Ni supplementation. Tissue Fe‐levels were positively correlated with tissue Ni‐levels.

Elemental composition of potted vegetables and millet grown on hard coal bottom ash-amended soil

Vegetables (bush beans, cabbage, carrots, onions, potatoes and tomatoes) and millet (Echinochloa crus-galli var. frumentacea) were grown in pots of soil amended with hard coal bottom ash and the magnitude of absorption of 23 elements by the plants was studied. At maturity, the crops were harvested and the edible portions collected for analysis. Results are tabulated. Most elements showed no consistent increase in concentration in the ash-grown plants. B, Cr, Mo, K, Na and Se were higher in at least 5 of the crops grown on ash-amended soil than the respective control crops. Toxic elements such as As and Cd showed no increase or only a modest increase in various of the plants grown.