Growing miscanthus helps reduce nitrates in groundwater

Growing miscanthus helps reduce nitrates in groundwater

MisEauVert, a collaborative R&D project funded by the ANR, focuses in particular on the effect of miscanthus cultivation on protecting water quality in catchment areas (AAC).

For this project, Loïc Strullu (INRAE Laon) carried out extensive modeling work at the AAC level. This work focuses in particular on nitrate flows under crops.

The study AAC, which is the St-Georges-sur-Eure Mérobert AAC, is located southwest of Chartres (Eure-et-Loir). It has been classified as a priority since 2009.

The modeling was conducted using STICS, a soil-plant-atmosphere simulation tool that has been under continuous development by INRAE and CIRAD since 1996. Currently,the scientific community makes extensive use of thethe STICS model in its modeling work.

In MisEauVert, this modeling work complements the monitoring of experimental miscanthus plots. Located in close proximity to the Saint-Georges-sur-Eure AAC, plot monitoring is based on the collection and analysis of drainage water. The system monitors a miscanthus plot and a control plot, measuring nitrates and plant protection products.

Purpose of modeling

The modeling focused on nitrate concentrations across the entire AAC, based on two scenarios:

  • the current scenario, which models current cultivation dynamics on the AAC.
  • and a low-input scenario (LIS), with 10% of the AAC area planted with miscanthus and 5% with other LIS crops: sunflower and AB.

The challenge is to answer questions such as:What is the nitrate concentration in the water below the soil horizon of the compared soils, between miscanthus, other BNI crops, and current crops?

A good level of accuracy and representativeness was achieved thanks to local databases and the involvement and knowledge of local stakeholders: Chartres Métropole, the Eure-et-Loir Chamber of Agriculture, and Gabel.

The modeling results show the significant impact of BNI crops in reducing nitrate concentrations in water.

The most significant effects are those of miscanthus, with a 53 to 59% reduction in nitrates compared to the replaced rotations. The NBI scenario, with 10% of the UAA in miscanthus and 5% in other NBI crops, allows for an average 11% reduction in nitrates compared to the initial scenario.

 

Summary available here: 24_02_2026_MisEauVert-Simulation at the AAC Mérobert scale-summary

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