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Soil health down to a tea

Stewardship
14.07.2020
Earthworm at GWCT project

Adopting reduced tillage establishment systems this season could help kick-start an immediate recovery in soil health, with benefits for soil microbial activity and carbon retention to potentially mitigate effects of climate change.

Citizen science at the Syngenta Ryegrass Innovation Centre in Yorkshire has used the Tea Bag Test to demonstrate an enhancement in soil health under a reduced non-inversion establishment system, compared to conventional plough.

Watch the video of Andy Cunningham’s trial here

The work has been further investigated and evaluated by researchers at the Game and Wildlife Conservation Trust’s Allerton Project, where Dr Jenny Bussell has been working on the Syngenta Conservation Agriculture initiative.

In Yorkshire, Syngenta Trials Manager and grass weed expert, Andy Cunningham, has trialled two techniques to give a gauge of the site’s soil health, in combination with establishment techniques being assessed to tackle difficult grass weed populations.

Andy Cunningham

The first, involving burying natural cotton baby grows in plots established with the different techniques, showed little or no discernible difference in degradation in the soil over a three month trial period.

However, even with the incredibly difficult weather and soil conditions, measuring the relative degradation of different tea leaves has proved a far more sensitive test, reported Andy.

The Tea Bag Index has become an internationally recognised scientific technique, promoted by the British Ecological Society.     

Tea bag test for soil microbial activity

The theory goes, explained Andy, is that the different carbon to nitrogen ratio of green tea, compared to red (Rooibos) tea, can indicate if there is microbial activity, and the relative health of the soil.

Assessing the results of the trial, Dr Jenny Bussell, highlighted the ‘K’ scores, for the rate of breakdown, and the ‘S’ rating of level of stability, indicated the reduced tillage did have a higher stability factor.

View the results interpreted by Dr Jenny Bussell

She pointed out the higher stability score with the reduced tillage system showed organic matter would be better retained and building up in the soil. “By reducing the tillage you have been protecting some of the beneficial microorganisms.

Andrew Barr's min till establishment autumn 2019

 “We are really interested in maintaining and building organic matter levels, as they are the basis for all soil life. It’s the function of the organic matter to feed the earthworms, which are the engineers of soil structure, so essential for plant growth,” enthused Dr Bussell.

“Soil health is essential for the sustainability of farming systems, and the productivity ensuring profitable farms year-on-year." 

"The problem with reduced cultivations is that it takes a long time to build that organic matter, but the Tea Bag Test has shown that it’s on the right track and, if you carry on that way, the slow stabilising of plant material will turn into organic matter.”

Jenny Bussell at R&D Showcase

Dr Bussell also pointed out that, with enhanced stability, when more organic matter is built up in the soil it is not being released as carbon gases. “One of the ways that we can tackle climate change and global warming is by sequesting carbon through plant material, and making sure it stays in the soil.

“The stability factor, as demonstrated by the Tea Bag Test, is all about saying how much of that carbon is staying in the soil, and not being released as CO2.”

Find out more on the research at the Syngenta Ryegrass Innovation Centre