Just released: Cover crops and intercropping systems help reduce nitrate and pesticide leaching.

What agronomic levers—combined with reduced pesticide use—can help limit pesticide transfer into drainage water? Spoiler: sometimes, it’s enough… not to leave the soil bare.

In a new article based on research from the CrosyeN project, entitled “Cover crops and intercropping help to reduce nitrate and pesticide leaching in low‑input systems” and published in Agricultural Systems, the authors analysed six years of data collected from several diversified arable cropping systems under real farming conditions.

• Objective: to determine whether low‑input systems can reduce nitrate and pesticide losses while remaining agronomically productive.

What was tested:

• Six cropping systems using diversified rotations, varietal mixtures, and species associations, with or without cover crops
• Monitoring of drainage water transfers
• Analysis of molecules applied before and during the experiment (≈ 44 molecules)
   

Key findings

• Diversifying cropping systems, especially through the introduction of multi‑service cover crops (CIMS), is a highly effective strategy for reducing agriculture’s environmental footprint.
• Cover crops reduce nitrate losses by 42–56%.
• Even more striking: they also reduce pesticide leaching for certain molecules by 53–82%.
• This includes S‑metolachlor, which accounts for more than half of the measured losses.
• Intercropping systems also help reduce these leakages.

One of the most original results of the study is precisely this clear reduction in pesticide leaching thanks to cover crops, an effect that remains very poorly documented at the scale of whole cropping systems.
 

Enjoy the read! And feel free to share your feedback or your own experiences with cover crops and diversified systems.

And because running such a long‑term experiment—and analysing pesticides in water over several years (539 samples!)—is expensive, a big thank‑you to the funders: the ANR through the Systerra MICMAC Design project, the France 2030 PEPR FairCarboN CrosyeN programme, the IntercropVALUES Horizon Project, and the Adour‑Garonne Water Agency through the MIXES project.

Finally, many thanks to the technical teams at INRAE Occitanie–Toulouse and INRAE UE APC (Experimental Unit for Agroecology and Crop Phenotyping).