Wheat Nutrition and Fertilizer Requirements: Micronutrients

Micronutrients are required for optimum crop production and the term micronutrient refers to the relative quantities required for plant growth and does not mean that they are any less important to plants than other nutrients. Wheat growth and development may be retarded if any one of these elements is lacking in the soil or if a nutrient is not adequately balanced with other nutrients.

Generally, the micronutrient content of most soils in Alberta is sufficient to meet crop requirements. The only significant micronutrient deficiency in wheat in Alberta is copper deficiency.

Copper deficiency is very common in wheat grown on organic or peat soils. Copper deficiencies have been confirmed on deeper (45 cm; 18 in) peat soils in different areas. On mineral soils a deficiency of copper in wheat may occur on neutral to acidic sandy textured soils that have been leached, and that are high in organic matter.

In wheat, copper deficiency shows up as a whitening and twisting of the leaf tip. This characteristic can be confused with frost damage. Copper deficiency is responsible for stem or head melinoses, a disease which causes browning of the head and upper stem. Light, shrivelled kernels are the result. On extreme deficient soils, cereal crops germinate, grow reasonably well in the vegetative stage but will not head out. The plant leaves are brownish in colour.

On peat soils, 5-15 kg/ha (4-13 lb/ac) copper sulphate should be thoroughly mixed with the 15 cm (6 in) of soil before planting. Disodium copper EDTA (or copper chelate) is thought to be more effective than copper sulphate, therefore only 1/5 as much copper is applied. For mineral soils suspected of being short of copper, 5-10 kg/ha (4-9 lb/ac) copper sulphate or 1-2 kg/ha (0.89-1.78 lb/ac) as copper EDTA should be applied.

For more detailed information on micronutrients refer to Agdex 531-1, Micronutrient Requirements of Crops in Alberta.

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