Trace element deficiency is quite important to consider for cereals in terms of plant health, with crops most prone to problems concerning copper, manganese and zinc.
Cereals also have a requirement for boron, molybdenum, chlorine, and iron but are not susceptible to deficiencies where these elements are concerned. Beet and oilseeds, however, are susceptible to boron and molybdenum deficiencies.
According to Teagasc, it is important that all crops have balanced access to all the major and micronutrients they need.
It is also important that crops use all the nutrients applied to them in the most efficient way possible.
Soil analysis for trace element deficiency
Identifying trace mineral-related problems will always start with a soil analysis. This approach will establish the micronutrient status of the farm as a whole.
The trace elements tested for are copper, zinc and manganese.
Results come with the proviso that a range of factors can influence manganese availability throughout the growing season.
The actual trace element levels, once known, can be best contextualised within an index system, similar to that used for the likes of potassium and phosphorous.
Soil type is also important. For example, in the north east the sand and shale type soils predominating there are strongly associated with a zinc deficiency.
Across the midlands, where lighter and peat-type soils predominate, manganese deficiency can be a problem, while the red sandstone soils that predominate in the south of the country can give rise to copper-related problems.
Additional factors that impact on the availability of manganese include soil pH. The trace element is more available in acidic soils to the extent that it can become toxic to plants at low pH values.
However, when pH levels rise above 7.0, the soil availability of manganese is reduced.
Seedbed consolidation and moisture availability will also impact on manganese accessibility. Dark green tracks on soil trafficked by tractor wheels, is a clear indicator of manganese deficiency within a cereal crop.
The better compression and moisture retention levels on the trafficked soil, leading to the very visible darker green colouration strips, will stand out in sharp contrast to the rest of a deficient crop.
Enhanced moisture contact with the crop roots will encourage manganese uptake.
In addition, certain cereal varieties are more susceptible to manganese deficiency than others.
According to Teagasc, manganese deficiency is the most widespread micronutrient challenge that shows up within Irish cereal crops on an annual basis. Interveinal browning on leaves is a strong indicator that the problem exists.
Deficiencies are best treated by the use of seed treatments and the application of proprietary foliar sprays. Soil treatments are not that effective.
Zinc and copper
Zinc is the second most common deficiency-related problem encountered by Irish cereal growers. Farmers should be on the lookout for bleaching from the base of the leaf.
Soil treatments will give a good, long-term solution to the problem. Foliar sprays can also be applied.
Copper is one of the least widespread trace element deficiencies found in Irish cereal crops. Spiralling of the leaves, excessive tillering and blind grains are strong indicators of the problem.
Soil treatments in the form of bluestone can give long term control whereas foliar sprays will deliver seasonal management of a copper deficiency problem.