WITH A background of a reduced number of seed treatments available, some novel new concepts are coming to the fore, including using zinc as a treatment for barley.

Using such a seed treatment to promote early plant growth has increased winter barley yields by more than 0.5t/ha for Fraserburgh farm manager, John Lamont.

Encouraged by his experience with i-Man, a manganese complexed-based seed treatment, on winter wheat and after consulting his agronomist, John Henderson, Mr Lamont decided to see if a zinc-based seed treatment would address the availability issues he believed were holding back his barley yields.

“It is often hard to identify which micronutrient is in short supply because nutrient availability is typically the result of many inter-related factors. Zinc is a prime example, so it was a case of trying something new, if only to rule it out as a limiting factor,” explained Mr Lamont, manager for GD Mitchell, Coburty Mains and West Crichie.

Zinc deficiency is notoriously hard to diagnose as it typically manifests as slower crop growth and increased susceptibility to disease. As a result, deficiencies are usually only identified by grain and leaf tissue analysis at which point the damage to performance has been done. Soil analysis, too, has limited value as this typically reveals what is present, rather than what is available to the plant.

“Our soil analyses suggested that zinc levels were within the normal range at between 3 and 4 mg/litre, but such results should never be viewed in isolation. As with much of Scotland, our soils are high in phosphate, typically

above 10mg/l. This is high enough to lock-up other nutrients and led me to question what may be being restricted as a result. Zinc is one of those elements, so the question was how best to address the issue?” he added.

Because zinc has been found to be vital to supporting early root growth, he quickly ruled out foliar treatments. This left ZAX, a specialist seed treatment from Agrii, as the most suitable means of application.

Using the winter barley variety, KWS Tower, he drilled roughly 5ha treated with Redigo Pro (prothioconazole + tebuconazole) only and 5ha treated with Redigo Pro + ZAX on September 27, 2017, at a slightly higher-than-usual seed rate of 235kg/ha due to less-than-perfect ground conditions.

“The treated crop was noticeably faster to establish and differences were visible up until the three-leaf stage. This satisfied any reservations I had about zinc’s contribution to plant establishment. It was difficult to assess any benefits to plant health as it was such a low disease pressure year, but at harvest the treated crop yielded, at a conservative estimate, 0.5t/ha more than the crop receiving only the standard seed treatment.”

At a cost of about £52/t for treated seed – equivalent to £10.40/ha at a seed rate of 200kg/ha – it was an easy spend to justify, he said and has since decided to apply the treatment to all home-saved winter and spring barley seed for the coming season.

According to Jim Carswell, Agrii’s research and development manager, wheat is the cereal most responsive to zinc with barley and oats in second and third respectively. “Zinc is one of those essential micronutrients we need to pay more attention too. It promotes auxin production which supports root growth which means the plant is better equipped to seek-out nutrients and is less prone to lodging.”

He said more growers were coming to recognise the benefits of micronutrient seed treatments – Agrii has also recently launched a new copper-based seed treatment of specific relevance to growers in Scotland, because 30% of Scottish soils are known to be deficient in copper.

“Where soil analysis suggests there is a deficit or where a high level of one nutrient may lead to a deficiency of another, specialist seed treatments are often the most effective means of addressing availability issues. With ZAX on spring barley, for example, we have seen

better yields through higher plant populations, typically 50-80 more ears per square metre, lower grain nitrogen levels and lower screenings,” he added.