Agronomy Research Expertise in Montpellier and Languedoc-Roussillon (South of France)

Agronomy : crops and cropping systemse

Keywords :

Managing nitrate pollution hazards in western Réunion

2. Minimizing the impact of cropping on biogeochemical cycles

2. Minimizing the impact of cropping on biogeochemical cycles

The population of the island of Réunion should increase by around 30% by 2030. Treatment of agroindustrial (effluents, composts, stillage, etc.) and urban (STEP sludge, waste water, mixed compost) organic waste will accelerate to overcome the structural delays. Moreover, in this island region, expansion of the urban fabric substantially hampers the development of agricultural areas. It is therefore crucial to increase and optimize organic waste recycling while sustainably managing two vital resources—soil and groundwater—and preserving them from pollution. Research was carried out to gain further insight into: (i) organic matter transformation processes in tropical soil, and (ii) the potential for using cropping systems to regulate water and solute flows in the tropical volcanic soils of Réunion. At the Colimaçons station, a plot was equipped with instruments to monitor water and nitrate flows to up to 2 m depth (photo 1). It was shown that, after slurry spreading, nitrate flows were very slow as compared to water flows, mainly due to the anion retention capacity of Andosols (figure 1). The nitrate pools formed in this way could be used by crops, with a high contribution to the annual nitrogen balance. It is possible to reduce the risk of leaching to optimize organic or chemical fertilizer applications by focusing on the uptake periods and on root growth patterns in the soil layer. In order to be able to apply the findings obtained in a research station to the many agricultural and soil-climate conditions of western Réunion, a thematic map of the vulnerability of the water table to soilborne pollution was drawn up (figure 2). This map shows that some areas are much more sensitive than others to nitrate transport hazards, and therefore improving agricultural practices should be a priority in those areas.

Contact(s) :
Hervé Saint Macary ,
Frédéric Feder ,
Nicolas Payet ,

Publication date : 30/05/2010


Payet N., Findeling A., Chopart J.L., Feder F., Nicolini E.A., Saint Macary H., Vauclin M. 2009. Modelling the fate of nitrogen following pig slurry application on a tropical cropped acid soil on the island of Réunion (France). Agriculture, ecosystems and environment, 134 (3-4) : 218-233.
DOI link/ publisher web site

Payet N., Nicolini E., Rogers K., Saint Macary H., Vauclin M. 2010. Evidence of soil pollution by nitrates derived from pig effluent using 18O and 15N isotope analyses. Agronomy for Sustainable Development, 30 (4) : 743-751.

DOI link/ publisher web site



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