Benefits of adding manganese to seed-beds after dry summer

Farmers are advised to apply manganese in the seed-bed this autumn, as the dry summer may have left soils depleted of the micronutrient.

Origin Soil Nutrition agronomist Toby Ward warns that the exceptionally long dry spells have meant soils have spent longer in oxidising conditions than in a more normal season.

Consequently, there has been more oxidation of the element.

See also: How polysulphate fertiliser can lift wheat yields by 0.3t/ha

The resulting manganese oxide is not soluble and is, therefore, not available to plants. This process is not readily reversible, so manganese won’t be available in the autumn even after the rain we have had.

He explains that it’s the same reason why manganese deficiency tends to occur in light and fluffy soils where the seed-bed has not been consolidated by rolling. Rolling reduces oxygen in the soil.

Soil testing

Toby notes that, while soil analysis can indicate good indices, broad spectrum tests typically measure the total manganese content in the soil.

However, this may not fully reflect the amount of manganese that is readily available to plants, so results should be interpreted with care and in context.

“Therefore, there could be a hidden problem, especially with intensively cultivated light soils.”

Most farmers tend to treat crops with a manganese foliar spray in the spring, often reacting to a problem.

However, once in the plant manganese is immobile. It stays in the leaves it is applied to and as new leaves emerge, they will not necessarily have manganese in them.

That’s why growers tend to reapply, for example at the T1 and T2 spray timings.

© Tim Scrivener

Instead, Toby advises farmers to proactively apply manganese in the seed-bed this autumn along with P and K to help prevent deficiencies.

He adds that it is not replacing the spring foliar applications, but is in addition, to fill the hunger gap until foliar applications.

“Getting manganese into the plant at an early stage increases photosynthesis and energy production, so you get more biomass (and roots) and a stronger plant that can better withstand winter.”

Then, come spring, the plants can get going quicker and earlier. This also helps to maximise tiller numbers.

Yield impact

Trial work at Origin shows that seed-bed applications alongside foliar sprays, does help increase yield and, therefore, profitability of the crop.

Toby points to one Irish trial in spring barley where there was a 4.7% yield increase and nitrogen uptake increased by 5.4%, resulting in a 8.2% improvement in nitrogen use efficiency.

In another trial in East Yorkshire, a seed-bed manganese application saw a 0.3t/ha increase in spring barley yield and when combined with foliar sprays, there was a greater yield increase of 0.91t/ha.

“This is why we advise that seed-bed applications should not replace foliar applications, but they complement each other.”

He explains that one of the easiest ways to apply is by using P and K fertiliser that is coated with manganese, so is delivered where the crop needs it.