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Micronutrients

What are you missing out on?

A good balance of nutrients in soil is essential for healthy crop production. Micronutrients are often described as the detonator or ‘firing pin’ in plant production systems – they are only needed in small amounts but they have a much larger impact on plant growth and processes than their abundance suggests. If your crop is missing out on just one micronutrient, this can limit the uptake of other nutrients and restrict plant growth and crop yield.

Micronutrients vs macronutrients

Micronutrients are essential for healthy plant growth but they are only used by the crop in small amounts. For every tonne of grain produced by a cereal crop only 14–20 grams of the micronutrient zinc and 3–5 grams of the micronutrient copper are removed from the system[i]. There are seven vitally important micronutrients: boron, cobalt, copper, iron, manganese, molybdenum and zinc.

Macronutrients are also essential for healthy crop growth but they are needed in large amounts. For example, 17–23 kilograms of nitrogen (N), 2.7 kg phosphorus (P) and 3.6–4.3 kg of potassium (K) [ii] are removed from the system with every tonne of grain harvested. There are ten macronutrients: carbon, oxygen, hydrogen, nitrogen, potassium, phosphorus, calcium, magnesium, chloride and sulphur.

Most fertilisers contain combinations of nitrogen, phosphorus and potassium as they are used by crops in such large amounts, but if the crop lacks a micronutrient then uptake of NPK and fertiliser can be limited.

How can I tell if micronutrients might be limiting crop growth?

Micronutrient deficiencies are often difficult to spot as the symptoms may only appear in the crop when the deficiency is severe. When zinc is deficient, cereals may not present any symptoms other than reduced top growth production. Australian soils vary considerably in nutrient content and some are naturally deficient in micronutrients. Micronutrient availability can also be influenced by a wide range of factors including soil pH, temperature, management and moisture. Soil and tissue testing combined with professional advice is the best way to check your micronutrient.

What difference can micronutrients make to my bottom line?

Getting the nutrient balance right is essential for a healthy, productive crop. Providing essential nutrients in the furrow at seeding can help to get your crop off to a good start. Prevention at seeding is much more effective than trying to treat the crop once the damage has been done.

Growers and agronomists have reported a 3–12 per cent increase in yield when they’ve adapted planting machinery to accurately deliver micronutrients in furrow. Applying micronutrients together with NPK fertilisers can have a greater impact on the plant than either product on its own. Liquid fertilisers containing nitrogen and micronutrients can also produce higher shoot weights and grain yields than granulated products on calcareous soils[iii].

Some growers using micronutrients in furrow for several years are also reporting less disease in their crops compared to their neighbours, saving up to $54,000 in fungicide costs in some cases, as well as increasing yield.

When nutrients are applied in furrow, the seed has immediate access to both macro- and micronutrients and plants are more likely to develop a strong, healthy root system consistently across the growing crop. A healthy root system allows the plant to: access more nutrients in the environment; grow stronger, faster; increase its resilience and ability to cope with changing environmental conditions; and ultimately increase its potential yield.

Liquid Systems (SA) can supply equipment for accurate in furrow application of micronutrients as a set ratio tank mix with water or liquid fertiliser, or via direct injection into a primary carrier stream for independent rate control. Liquid Systems (SA) units can deliver multiple products at differing rates in the one application and are designed to be extremely accurate when delivering small amounts of liquids. This means that exactly the right amount of micronutrient is delivered into the root zone of your crop – increasing your fertiliser use efficiency and water use efficiency. In furrow micronutrient application also avoids the headache of handling wet seed and granules during coating and is more efficient and cost effective than pre-treated granules.

Each paddock will have different requirements, so soil and plant tissue testing is essential to make sure that your crop nutrition is balanced and you’re not missing out on micronutrients.

More information

Contact Patrick at Liquid Systems (SA) on +61 8 8357 4437 to find out more about in-furrow application of micronutrients.

More information about specific micronutrients is available in a newly-released fact sheet from the Grains Research and Development Council (www.grdc.com.au/GRDC-FS-CropNutrition-Micronutrients), which also lists several suppliers of soil and plant tissue tests.

[i] http://soilhealthknowledge.com.au/index.php?option=com_content&view=article&id=37&Itemid=94&limitstart=6, accessed 13/1/2014 http://www.sardi.sa.gov.au/__data/assets/pdf_file/0018/45027/sustain_nutrient_broadacre.pdf

[ii] http://soilhealthknowledge.com.au/index.php?option=com_content&view=article&id=37&Itemid=94&limitstart=6, accessed 13/1/2014 http://www.sardi.sa.gov.au/__data/assets/pdf_file/0018/45027/sustain_nutrient_broadacre.pdf

[iii] http://www.fluidfertilisers.com.au/index.php?id=4