InterRoot - Harnessing Root System Dynamics to Unlock Cereal-Legume Intercropping Partnerships in Organic Agriculture

Tackling the Organic Yield Gap from the Ground Up

Conventional farming relies on abundant synthetic fertilisers and pesticides to secure high yields, but these inputs carry heavy environmental and economic costs. Organic agriculture, by contrast, makes the most of natural resource cycling, yet the majority of modern cereal and legume cultivars were bred for nutrient-rich, low-stress conditions. However, they therefore often underperform as inputs are limited and pests, weeds, and diseases are more prevalent.

One promising way to bridge this “organic yield gap” is intercropping - growing two or more crop species together to promote mutual benefits such as improved nutrient use and pest resistance. Despite its potential, intercropping remains underutilised, and the reasons why some crop combinations work better than others are still not fully understood. This is especially true for the interactions taking place below ground.

 
Why Focus on Roots?

While most intercropping studies focus on aboveground traits like canopy structure, light competition, or crop height, we argue that the belowground interactions between crop species are no less important. Roots govern water and nutrient acquisition, influence microbial communities, and play a critical role in soil structure and function.

Complementary root systems - e.g. a deep-rooted legume grown next to a shallower-rooted cereal- can reduce direct competition and increase overall resource capture. However, current research tends to focus on species-level pairings and rarely explores the diversity among crop varieties.

Yet this variation within species may be important. Different varieties can differ in root depth, angle, growth timing, and interaction with neighbouring plants. These differences offer a largely untapped opportunity for improving organic intercrop performance.

 
The Aim of InterRoot

InterRoot aims to identify cereal-legume intercropping variety combinations that are optimally compatible below ground.

We will focus on root architectural traits - including depth, angle, distribution, and growth timing - that influence how crops use soil space and resources over time. The project will assess how root complementarity can enhance nutrient acquisition, particularly nitrogen and phosphorus, with the goal of improving yields without synthetic inputs.

Rather than only asking which crop species can be grown together, InterRoot asks which varieties are most compatible, and which root traits help make these combinations work.

The project will begin by screening a wide selection of cereal and legume varieties currently grown in Sweden in both controlled environments and field conditions. From these results, we will select the most promising crop teams and test how their root systems relate to nutrient uptake, yield, grain protein content, weed pressure, and other traits relevant to organic production.

In short, InterRoot aims to help identify crop varieties that work better together - not only above ground, but from the roots up.