quantification and control nitrates flow: from the drained parcel at the watershed

Abstract

To study the nitrate transfers through of nitrate in a context of subsurface drained plot makes it possible to highlight the main processes of leaching. The presence of the drain pipe at 1 m deep strongly modifies water and nitrates pathways. The concentrations measured at outlet of drained plot (site of Jaillière) are related to the localization of the nitrogen stock between drain and interdrain. A pluri-annual approach introduces the concept of leaching cycle whose nitrate residue management at entry-winter is a key. At watershed scale, (site of Orgeval), the comprehension of the nitrate concentrations is more complex: the interactions between groundwater, river, ripisylve are observed on various space scales. In addition to the adaptation of BMP's at plot scale, the restauration of landscape retention zones facilitates processes of nitrates elimination (benthic and riparian denitrification). Those complementary mitigating solutions make part of nitrate management within a watershed.