FACTS

• Cobalt (Co) has a relatively low abundance in the earth’s crust (26.6 mg/kg on average)
• It is recognized as a beneficial element for legumes at low concentrations (0.1-10 μg/g biomass); legumes, sugar beets, wheat, rice and grapes are the most sensitive to cobalt deficiency
• Cobalt stimulates the activity of several key enzymes and facilitates biological nitrogen fixation
• Crop yields take from 5 to 50 g/ha of cobalt
• Cobalt fertilizers include cobalt sulfate, cobalt chloride and cobalt nitrate
• Cobalt-containing fertilizers are especially recommended for meadows and pastures

FUNCTION

• Role in the regulation of specific growth processes, including coleoptile elongation, leaf expansion and bud development (effect on auxin metabolism and cell membrane elasticity)
• Involved in physiological processes including synthesis of photosynthetic pigments, amino acids metabolism and alkaloid biosynthesis
• Affects crop tolerance to drought by regulating water uptake and reducing the transpiration rate

AVAILABILITY

• About 50 percent of cobalt in plant tissues is present in ionic form — 20 percent in the form of cobamide compounds and the rest as part of vitamin B12
• Cobalt bioavailability depends on soil pH, Co concentration, speciation and partitioning; it is also influenced by the presence of Fe and Mn oxides and clay minerals, soil organic matter content and soil redox potential
• Once absorbed by the plant, Co is primarily accumulated in roots

Credits: Michał Słota, Ph.D., Content Farmers