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 modern cereal and legume cultivars were bred for nutrient rich, low stress conditions and thus often underperform when 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 its mechanisms are still not fully understood – especially those operating below ground.

While most intercropping studies focus on aboveground traits like canopy structure or light competition, 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 – for example, a deep-rooted cereal grown with a shallow-rooted legume – can reduce direct competition and increase overall resource capture. However, current research tends to focus on species-level pairings and rarely explores the intraspecific diversity among crop varieties. Yet, the genetic variation within species can lead to significant differences in root architecture and interaction dynamics – a largely untapped opportunity for improving organic intercrop performance.

The Aim of InterRoot

InterRoot aims to identify crop legume-cereal intercropping variety combinations that are optimally compatible belowground. We will focus on root architectural traits (e.g. depth, angle, growth timing) that influence spatial and temporal resource use in intercropping systems. The project will assess how root complementarity can enhance nutrient acquisition, particularly nitrogen and phosphorus, with the goal of improving yields without synthetic inputs.

The project will begin by screening a wide selection of cereal and legume varieties currently grown in Sweden - including modern and heritage lines – in both controlled environments and field conditions, quantifying root growth and interaction patterns. Based on these results, we will select the most promising teams and evaluate them in in detailed rhizotron facilities and organic field conditions near Uppsala and on Öland. Measurements will include yield, nutrient uptake, grain protein content, weed pressure, and other functional indicators relevant to organic production. Special attention will be given to identifying variety traits that are consistent across different soil types and environmental conditions.

Why This Research is Timely and Necessary

Despite rising interest in organic intercropping, fundamental knowledge about root-root interactions and varietal compatibility is lacking. Given that organic systems rely on ecological processes rather than synthetic inputs, the efficiency of root systems becomes a key factor in productivity. InterRoot addresses this gap by bringing together plant physiology, agroecology, and potential for breeding – generating actionable knowledge for farmers and plant breeders alike. The long-term goal is to provide concrete variety recommendations for intercrops tailored to organic conditions. By focusing on root interactions as a driver of yield and nutrient efficiency, InterRoot promotes farming systems that are less dependent on external inputs and more resilient to environmental variability.