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Targeting biostimulant and micronutrient use
Targeting biostimulant and micronutrient use
by Arable Farming August 2020
A science-led approach to evaluating biostimulants and micronutrition is helping to pinpoint when, where and how they can make a difference. Arable Farming reports.
There is without doubt an increasing role for biostimulants and micronutrients and several reasons why this is the case.
That is the view of ProCam regional technical manager Nigel Scott, who says understanding of this group of crop inputs is improving, as is knowledge of how crop plants respond to them.
He says: Firstly, we are learning more about them and gaining more understanding that the healthier a plant is, the better it tolerates stress. Conversely, we know stressed plants are more susceptible to certain diseases.
Secondly, as we face issues such as the loss of crop protection active ingredients and resistance, we need to find additional ways to safeguard, or even bolster, crop health and output.
In response, some five to six years ago, ProCam embarked on a rigorous testing programme in a bid to pin down promising biostimulant and micronutrient treatments. Some are formulations of seaweed extracts containing important trace elements, others are more specialist, notes Mr Scott.
Comprising a three-step process, similar to how crop protection products might be evaluated for efficacy, testing begins with independent screening of a wide range of treatments in glasshouse pot tests.
From here, promising candidates are put into field trials. Finally, those that come through trials successfully progress into field-scale comparisons on-farm.
Treatments
Much of the early stage work is focused at our central research and trials centre at the Stockbridge Technology Centre, Cawood, York, says Mr Scott.
But we also evaluate promising treatments in our wider UK network of trials.
Glasshouse tests encompass crops such as wheat, barley and oilseed rape, but we have also looked at maize. These tests are designed to single out treatments that produce the most positive improvements in root and shoot growth when applied to young plants.
In the field, investigations are broadened to also include mid-season applications, to assess any additional effects on plant health. At the end of the season, plots are taken to yield.
Reviewing the findings, Mr Scott says although there are treatments where results have been less conclusive, others have delivered more consistent and compelling improvements.
He says: Early applications across multiple crops have shown some significant gains in root weights from applying certain treatments to young seedlings. In some cases, within a month of applying, root weight was increased by well over a third.
With these types of result, there is a clear argument for considering autumn biostimulant + micronutrient applications, for example, in challenging establishment situations. But we have also recorded substantial plant health benefits from spring applications, including reductions in certain diseases.
Pointing to examples, Mr Scott says Scottish spring barley work last year showed leaf damage at GS72 from ramularia, a disease known to flare up when plants are stressed, was cut by almost half from 30% to 16% following biostimulant plus micronutrient applications at GS30/31 and GS45/49.
By comparison, although application of the fungicide chlorothalonil at the same spray timings resulted in zero ramularia infection, chlorothalonil can no longer be used, says Mr Scott.
So there is a good case for targeting stress reduction with these types of treatment to support alternative fungicides, he believes. Reductions in septoria infection have also been seen in winter wheat.
Septoria
Mr Scott says: Plots at our Cawood trials hub last year showed septoria on leaf 3 was halved from 20% to 10% where a biostimulant + nutrition programme was applied compared with untreated . Some even bigger septoria reductions were seen on leaf 4 below.
Again, reductions were greater where fungicides were applied.
But more interestingly, the lowest levels of septoria were seen where the biostimulant + nutrition programme was co-applied with the fungicide.
By creating a healthier plant, not only could it improve its ability to fight disease, but fungicides may also work better, because they are being applied more preventatively. Similarly, if a fungicide is late being applied, a healthier plant may be better able to cope.
Towards the end of the season, Mr Scott says trials have also shown wheat plants remained greener after receiving a biostimulant and nutrient programme, while untreated plants started to senesce.
As the ultimate test, substantial yield improvements have also been seen from adding biostimulants + micronutrients to fungicide programmes in two out of three seasons of trials at Cawood ranging from 0.4 tonnes per hectare to an extra 2t/ha.
In the 2018 season, across two different winter wheat varieties, including the biostimulant + micronutrient programme boosted average yield by an extra 1.7t/ha.
Most significantly, this was on top of the yield from a full, four-spray fungicide programme, which itself had given an extra 1.2t/ ha over untreated. If you recall,
2018 was very dry, so improved rooting may have been a key factor behind this big yield gain.
In farm comparisons, we have also seen an extra 0.5-0.6t/ha achieved from including biostimulants + micronutrients over back-to-back years.
How to use biostimulants and micronutrients
There are three key phases in a combinable crops life when biostimulants and micronutrients can have a role, says Nigel Scott.
These include: to accelerate growth during establishment; to boost flagging or poorly-rooted crops coming out of winter and, finally, a more programmed, little-and-often approach to keep plants topped up against stress and nutrient deficiencies through spring.
Mr Scott says: As an example of helping plants during establishment, with the loss of neonicotinoid seed treatment chemistry, along with other management methods, we should be trying to get winter oilseed rape plants to two true leaves as rapidly as possible. At this stage they become more resilient to adult flea beetle damage. By five leaves, crops are also building a good root mass and healthy plant stands with thicker root collars are more resilient to flea beetle larvae.
Rooting
Turning to flagging crops, Mr Scott says winter 2019/2020 provided a prime example of when late-planted and backward cereals would have benefited from improved rooting.
In wheat, there is a relationship that says the longer the roots are at flowering, the higher the yield.
For little-and-often spring applications, our approach is to keep the plant supplied with essential nutrients through the main growing period before they become limiting.
A plant can be deficient in manganese, for example, before symptoms appear.
By co-applying with the fungicide programme you are taking steps to protect crops against different weather scenarios.
If the season turns dry, with improved root mass, plants are better able to scavenge for soil moisture and nutrients. If it turns wet and disease pressure is high, the fungicide part of the tank-mix protects yield.
Good quality treatments neednt be expensive. One of our benchmark products has been a particular combination of seaweed extract with nutrients.
Historically, seaweed products may have been viewed with scepticism, but this treatment has proved useful in promoting root and shoot growth and we have seen positive yield benefits, he adds.