Healthy plant growth and development depends on an ability to sequester all mineral nutrients from the soil but challenges often arise due to their relative immobility.

A two year study evaluating soil health and nutrient use efficiency has demonstrated the value of feeding soil microbes to unlock primary, secondary and micronutrients.

The work, conducted by an independent research station, compared a blend of 10% L-CBF Boost and 90% urea ammonium nitrate (UAN) with a full rate of UAN. To measure the impact, soil samples at 15cm depth were taken before application and again two weeks post-application.

QLF Agronomy
’s David Maxwell says the results show that including 10% L-CBF Boost with UAN improves nutrient availability while providing the soil microbes with biodiversity.

“There’s long been a focus on the role of nitrogen in improving soil and plant efficiency. However, we shouldn’t forget the importance of the remaining primary, secondary and micronutrients such as phosphorus, potassium, calcium, magnesium and sulphur.

“The trial results show that all mineral nutrients listed, beyond nitrogen, have surpassed nutrient efficiency compared with the control treatment,” he says. “Equally, given current concerns regarding soil nutrient availability and leaching, getting what’s available into the plant will be of paramount importance.”

NIAB trials

To that end, David says reducing nitrogen levels might not be appropriate following a wet autumn and winter. “The implications of nutrition being washed out of the soil, as well as soil biology possibly being compromised due to flooding and excessive moisture, means this isn’t necessarily the year for spring fertiliser applications to be reduced. It may be prudent to use ‘normal/farm standard’ applications and add L-CBF Boost to compensate for potential shortfalls.”

A study conducted by NIAB shows the benefit of this approach – when a total 200kgN was applied to a crop of winter wheat with a supplementary L-CBF Boost at GS25, the yield was 9.88t/ha compared with 9.34t/ha for nitrogen alone.

Feeding microbes

But how does feeding soil microbes actually work? David says it’s based on the concept of modulating the development of crop seedlings.

“This triggers a number of actions such as root hair elongation, root branching and a gravitropic effect on roots. It’s due to a process researchers coin the ‘rhizophagy cycle’, where microbes obtain nutrients from the soil, and nutrients are extracted from microbes in the cells of plant roots.”

“The greater the root network and soil biology, the greater the chance the seedling will have of mining residual or applied nutrition in the soil,” he says.

“By feeding the soil directly and realigning the co-dependency between the crop and the microbes, the plant can reserve its own energy and redirect into other useful processes.”

On-farm results

From an on-farm perspective, Gloucestershire based Jake Freestone has been using L-CBF Boost as part of a drive to increase the efficiency of applied inputs in a cost effective way.

“We include it with all synthetic applications to all crops, which has allowed us to cut back our use of artificial inputs by enough to keep it cost neutral, without compromising the efficacy of the input and reaping the added benefit of increasing soil health,” he explains.

Application guidance

L-CBF Boost contains filtered cane molasses and a range of nutrients and growth-promoting compounds, including nitrogen, potash, sulphur, amino acids and organic acids.

It’s applied at planting as well as with spring fertiliser applications, and can be used with a range of combinable crops. “Whether growers are aiming to recover winter crops or plant spring crops, providing adequate nutrition will be vital following months of waterlogged soils and stress,” concludes David.

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