What happens when you test legume–cereal intercropping in semi-arid environments? At ICA-CSIC in Spain, María José Carpio, César Plaza, and Juan Carlos García-Gil are studying how legume-cereal systems perform in such challenging environments. Their research spans soil and plant sampling, on-site greenhouse gas monitoring, and extends beyond the lab to outreach activities with farmers, stakeholders, and students.
In this interview, they share what they have learned so far and explain why even small changes in the soil can lead to big climate and sustainability benefits.
ICA-CSIC: “We are María José Carpio, César Plaza and Juan Carlos García-Gil from the Instituto de Ciencias Agrarias (ICA) of the Spanish National Research Council (CSIC).
Within the LEGUMINOSE project, we are responsible for the iCROP field experiment. Our role involves coordinating all field activities and collecting data for chemical and biochemical soil analyses, as well as measuring agronomic parameters and greenhouse gas (GHG) emissions. Our goal is to assess the performance and environmental impact of legume–cereal intercropping in semi-arid environments.”
Looking back…
ICA-CSIC: “Over the past two years, we have been running in the iCROP field trial. Here, we collect data on soil and plant parameters, assess crop yields, and monitor GHG emissions. We have also presented our work at five national and international conferences and workshops, and organised a range of outreach activities, including field visits, educational workshops, and public science events.”
…and ahead
ICA-CSIC: “We are currently analysing and processing a large volume of leaf and stem images collected at three phenological stages to calculate the Leaf Area Index (LAI). This index is an important parameter for understanding crop growth and productivity. In parallel, we have just completed the milling of all plant organs from the three phenological samplings for nutritional analysis. This has been one of the most detailed and time-consuming datasets we have worked on so far, involving careful processing of both plant and soil samples.
Looking ahead, we are excited to see how these results will help us better understand the environmental and agronomic benefits of intercropping in semi-arid conditions.
We would like to highlight two upcoming outreach activities related to our iCROP experiment:
- Autumn School Workshop in October 2025: A one-day seminar for vocational students in agronomy, agroecology, or related disciplines. The workshop combines theoretical sessions on intercropping with hands-on field activities at the La Poveda experimental farm.
- Workshop and field visit for Madrid’s Science and Innovation Week in November 2025: An event for local farmers, agronomists, and the science-interested public that includes interactive discussions followed by a guided field visit.
These events aim to foster knowledge exchange on sustainable agriculture and promote intercropping as a sustainable strategy in semi-arid systems.”
From challenges…
ICA-CSIC: “One of our biggest challenges has been managing the complexity and volume of data needed for our research – from image analysis and biomass processing to detailed soil measurements. The workload has been intense and required careful coordination, especially during peak sampling and analysis periods.
We tackled this by working closely as a team, planning ahead, and dividing tasks effectively to keep everything moving. It has been demanding, but also rewarding to see the full picture come together — and to know the data will support meaningful insights on intercropping systems.”
… to surprises
ICA-CSIC: “One of the most surprising insights was seeing how well legume-cereal intercropping performed in semi-arid, rainfed conditions – even with limited water. It improved land use efficiency, reduced fertiliser needs, and enhanced overall system performance.
We also noticed positive changes belowground: stronger associations between crops and beneficial mycorrhizal fungi, improved nutrient cycling and enhanced soil health. On top of that, intercropping also contributed to reducing greenhouse gas emissions, specifically N₂O emissions due to lower fertiliser application. The microbial communities in the intercropped plots also used carbon more efficiently, reducing CO₂ losses.”
The value of intercropping
ICA-CSIC: “Intercropping offers a practical strategy to improve soil health, make better use of resources, and enhance the resilience of farming systems, especially in semi-arid conditions. However, its implementation for grain production still raises questions among stakeholders, such as farmers and the feed manufacturing industry, primarily due to a lack of information or knowledge. That is why sharing research results and building trust is so important.”
From fungal networks to carbon efficiency, the ICA-CSIC team’s findings offer a glimpse on the hidden dynamics beneath the soil surface of intercropping systems. Their work shows that even under dry and challenging conditions, carefully designed field trials can reveal not only yield benefits, but also deeper environmental advantages worth paying attention to.