igzo.] French Agricultural Soil Maps. 



57 



FRENCH AGRICULTURAL SOIL MAPS. 



Lieut. -Colonel Louis Tebbutt has forwarded to the Ministry 

 a sample of agricultural maps drawn up by the Agricultural 

 Experiment Station of the Department of the Somme. The 

 maps are placed in the Communal Town Room for inspection 

 by all interested. The map is reproduced here to show their 

 general character. It is really a large-scale geological map 

 such as can be obtained from the Geological Survey of this 

 country, but it contains in addition information as to soils 

 derived from actual analysis. 



The drawing up of these maps has long been carried out in 

 France, the work being particularly associated with the Station 

 Agronomique de TAisne at Laon. Ever since 1856 M. Risler, 

 then Director of the Institut Agronomique, has drawn attention 

 to the close relationship between geological origin and soil 

 type, which in France has subsequently been strongly 

 emphasised ; writers have even claimed that soils derived 

 from the same geological stratum have the same composition. 



The colours on the map show the geological formation 

 (Couches Geologiques). The little columns in the numbered 

 oblongs show the chemical composition of the soil, the yellow 

 column on the right-hand side giving the percentage of total 

 lime (not carbonate, as would be given here* ; the three left- 

 hand columns show the number of parts per thousand (i.e., 

 percentages multiplied by 10) of nitrogen (slate coloured), 

 phosphoric acid and potash. The circles with coloured 

 sectors show the mechanical composition, the soil being sub- 

 divided into humus, chalk, sand and clay : these terms possess 

 a definite meaning well understood by French agricultural 

 experts, though they do not correspond exactly with the same 

 terms as used in this country. Thus the " humus " nearly 

 corresponds with our " Organic Matter," but is quite different 

 from our " Soluble Humus " ; the " chalk " is our "Carbonates 

 reckoned as calcium carbonate " ; the " sand " is our " Coarse 

 Sand " and some " Fine Sand," while the " clay " is our " Clay," 

 " fine silt," " silt," and some " fine sand." 



The map is certainly very interesting and could be used 

 effectively in discussing local experience with lime, fertilisers, 

 etc., and the results of agricultural and horticultural trials. 

 A village schoolmaster who was also a keen gardener could, 

 with his local knowledge, make considerable use of it. 



* Where the yellow column in the diagrams on the map is broken in the 

 top division, the percentage of lime is higher than can be shown in the 

 columns. 



