Increasing the value of UK farming soils

As we seek to reduce fertiliser use, conserve water and increase yields, improving the practical benefits from certain soil microbes may hold the key to achieving greater value from farming soils.

The paper acknowledges that the green revolution technologies, that saw the mass use of macro fertilisers, and indeed the shift in some economies from starving nations to net exporters of food was a 'one time innovation'. Other work reports that this approach to farming may have disguised the underlying status of our soils and contributed to a build-up of locked nutrients with only 5-10% of all inputs ever reaching the plants they were intended to support. Coupled to the demand for removal of many crop protection inputs, and world phosphorus reserves coming under strain in the coming decades, those with an eye on the strategic nature of farming are once again looking at how to harness soil biology to unlock bound macro elements, increase nutrient availability and thus reduce artificial inputs on a commercial scale.

Within the long list of species and strains of soil microbes that contribute to soil functionality, one of the most well characterised and arguably the most important group is mycorrhizal fungi. These microbes link to plant roots and extend a vast network of fungal hypae into the soils that function like a secondary root system. Research to understand the value and function of mycorrhizal fungi has been a global endeavour with groups across the world contributing to more than 60,000 technical papers and articles over the last fifty years representing many tens of millions in investment. It is well documented that one major function of mycorrhizal fungi in soils is to significantly enhance phosphorus uptake. But more recent work has shown that enhanced nitrogen and micro nutrient uptake is also significant, together with locking essential soil carbon in the upper soil horizons. Strictly speaking, 90% of land plants don't just have roots they have a 'mycorrhiza' which describe this root fungal union.

Where the use of predatory insects has now formed part of horticulture culture through Integrated Pest Management (IPM) the general use of soil microbes, from fungi through to bacteria, is now being recognised as practical farming tools and may well soon enter the lexicon of farming. It is noteworthy that recent joint ventures between Monsanto and Novozymes, FMC Corporation acquisition of RTI International, to name but a few, show a commercial alignment to the general area of soil microbes.

Far from being of academic interest, the use of manufactured mycorrhizal fungal inoculum in the UK is now well established and a number of demonstration and extended research projects are under way. Following on from an EU funded project at East Malling Research, where yield increases of up to 20% were noted on strawberry output over three years; the use on mycorrhiza on a commercial scale will be explored in a new TSB project in collaboration with Agrovista and BerryGardens. NIAB have also completed a year’s demonstration activity targeting soya, sainfoin and turf grass where significant germination and early growth effects were noted that form the basis of further work going forward, including work on onions in association with Tesco.

The use of mycorrhiza in forage grasses heralded the first use of these fungi at field-scale in UK farming through introduction of fungal inocula and the value of its use is now being explored with extended trials by collaborating seed houses including Limagrain and Cotswold Seeds across selected herbal and forage leys.

The use of mycorrhizal fungi and other classes of soil microbes, such as plant growth promoting rhizo-bacteria has become common practise in agriculture some parts of the world, from wheat in Canada to cassava in Brazil, but its benefit and use in the UK is now emerging. One factor that needs to be understood in the application of this technology is that these fungi cannot grow without a host plant partner. Although many of the cereal and horticultural crops are good hosts, some are not, including the Brassicaceae (cabbage family), and a season with a non mycorrhizal crop rotation will significantly reduce functional mycorrhizal fungi in the soil; this can reduce yields of the following crop. Conversely, the inoculation of a crop, during planting, with mycorrhizal fungi may not have to be an annual activity if farming practices are structured to ensure that these soil microbes are well supported in the soil, through rotation selection and the careful use of fungicides. The quest to define good farming practises to both introduce and maintain mycorrhizal fungi levels is a key focus in much of the current UK research effort in this field.

As we seek to modulate artificial inputs in farming and maintain and increase yields, it is clear that soil biology has a key role and the remarkable mycorrhizal fungi will need to play its part. For further information please contact collaborating organisations:

Dr Lydia Smith

Head of Innovation Farm

NIAB, Huntingdon Road

Cambridge CB3 0LE

Tel +44 (0)1223 342242

w: www.innovationfarm.co.uk

Ian Misselbrook

Limagrain UK Ltd

Rothwell

Market Rasen

Lincolnshire

LN7 6DT

e: SWFuLm1pc3NlbGJyb29rQGxpbWFncmFpbi5jby51aw==

Paul Totterdell

Assistant Manager

Cotswold Seeds Ltd

t: 01608 653203

e: cGF1bHRAY290c3dvbGRzZWVkcy5jb20=

w: www.cotswoldseeds.com

Mark Mackie

PlantWorks Ltd

Unit 930 Cornforth Drive

Kent Science Park

Sittingbourne

Kent

ME9 8PX

t. +44(0)1795 411527

e: aW5mb0BwbGFudHdvcmtzdWsuY28udWs=

w. www.rootgrow.co.uk