System of 42 plots

The “42 plots” long-term experimental system was created in 1928 by Albert Demolon at the Station Centrale d'Agronomie at the “Centre National de Recherches Agronomiques” in Versailles. The initial aim was to determine the effects of prolonged application of the main N, P and K fertilizers, as well as limestone amendments, on the composition and physical properties of aeolian silt soils characteristic of the Paris Basin and Northern France.
Plots measure 2 x 2.5 m. The experiment includes 16 different treatments in 2 replications, as well as 10 control plots, with no inputs whatsoever. For 85 years, the management of the system has been unchanged: annual fertilizer and soil improver application at a fixed dose, maintenance of the plots without vegetation, spading of the surface horizon twice a year (spring, autumn).
Since the 1980s, the use of the device has evolved: thanks to archives of historical samples, it now acts as a recording device for environmental quality (accumulation and fate of atmospheric fallout of metallic micropollutants and radioelements); it also occupies a central place as an experimental model, for example for studies on the temporal dynamics of different pools of matter.