Scientists investigate potential of plant traits and intercropping to reduce reliance on fertilisers

"The benefits of intercropping are clear in other contexts too, like the control of pests and disease or nitrogen use, but we have the first concrete evidence on how intercropping or these specific traits could affect P use.

Ongoing research by the James Hutton Institute, Rothamsted Research and Lancaster University is shedding light into the dark world of roots and soils, by focusing on the potential of plants to harness the phosphorus (P) already present in soils and reduce reliance on phosphate-based fertilisers.

It’s a well-known fact that phosphate fertilisers required for crop production are non-renewable and represent a significant cost to farmers. Moreover, if applied in excess, P pollution can lead to unwanted environmental impacts such as the ‘greening’ of aquatic systems due to harmful algal blooms.

To improve the efficiency of P use in agricultural systems, alternative and innovative fertilisation and cropping methods are necessary. The approaches being focused on by the consortium, better known as OPUS (Organic Phosphorus Utilization in Soils), include the selection of key plant traits or combinations of plants with the ability to release organic acids and enzymes from roots. These plant products interact in soil to unlock P bound to minerals and organic matter and then convert it to a form that plants can use.

OPUS members from the James Hutton Institute have found that P efficiency is improved through multiple approaches including the intercropping of cereals and legumes with these traits. “What’s interesting is that intercropping, and all its inherent benefits, is actually a traditional farming practice, which became unfashionable when agriculture became industrialized and focused on monoculture production”, said Dr Tim George, a rhizosphere scientist on the project at the James Hutton Institute.

Dr Courtney Giles, a post-doctoral researcher on the project, commented: “The benefits of intercropping are clear in other contexts too, like the control of pests and disease or nitrogen use, but we have the first concrete evidence on how intercropping or these specific traits could affect P use.”

This work also supports broader ecological theories, such as those proposed by Dr Rob Brooker and colleagues at the James Hutton Institute, on the benefits of increasing biodiversity in cropping systems, “But in this case”, Dr George added, “we’ve demonstrated that these theories hold true from a nutrient-perspective as well.”

The final year of the OPUS project will culminate with a week-long international workshop in the Lake District of England, which will bring together organic phosphorus researchers from across the world, to discuss how our understanding of soil phosphorus dynamics could be used to develop practical solutions to global P scarcity.

All are welcome to join Drs George and Giles in a discussion and demonstration of cereal and legume intercropping and how it improves P use this June at the James Hutton Institute LEAF Technical Day. For more information on P, its use in agriculture and behaviour in soils, see the OPUS group forum.