G. W. Robinson 355 



The agricultural value of these soils varies according to climate and 

 situation. In sheltered places the standard of cultivation is fairly high. 

 In the counties of Shropshire and Montgomery where considerable areas 

 of these soils occur in sheltered valleys, the farming is very good. This 

 is also true of the outlying areas in Anglesey and Carnarvonshire. 



In Denbighshire, where the Palaeozoic silt loam is typically developed, 

 and where it forms so large a part of the total area, the farming may 

 be described- as good second-rate cultivation. The rotation of crops 

 is similar to that practised in Anglesey. Denbighshire is largely a 

 county of sheep-farming: the upland moors provide abundant rough 

 grazing in the summer months. While the Anglesey medium loam 

 would appear to be suitable for further development in the direction 

 of market gardening, it cannot be said that this type of soil as developed 

 in Denbighshire is likely to be suitable for a more intensive svstem of 

 husbandry, although there is room for much improvement along the 

 lines of existing practices. 



The Palaeozoic silt loam of Anglesey shows very little difference from 

 the rest of Anglesey in the agriculture practised on it, except that the 

 grass land is possibly a little better than on the Anglesey medium loam. 



The average composition of forty-nine samples is shown in the general 

 table. As will be seen from the figures for range and interquartile range 

 these soils form a very well-defined type. The most noteworthy feature 

 is that the fine silt is the dominant fraction, being on the average 

 nearly 29 % of the soil. The percentage of clay is only 6-6. The 

 consequence of this is that these soils are very sticky when wet but, 

 owing to the comparatively small amount of clay and, possibly, to the 

 high proportions of gravel and organic matter, are fairly friable on 

 drying. A number of determinations of plasticity were made according 

 to the method of Atterberg^, The largest plasticity number obtained 

 was 10 for a Carnarvonshire soil containing 30-5 % fine silt and 12-35 % 

 clay. This may be compared with the figure 23-9 obtained for a glacial 

 clay of the vale of Clwyd. In order to determine the effect of fine silt 

 on the plasticity of a soil, the clay was removed by sedimentation from 

 a soil containing 34-4 % of fine silt and 14-9 % clay. The residual 

 material was found to have entirely lost its plasticity, i.e. it could only 

 be rolled without disintegration when it contained so much water as to 

 render it capable of behaving as a fluid. 



Chemically these soils are notable for their high proportions of 

 potash soluble in hydrochloric acid — -80 % on an average. Phosphoric 

 ^ Int. Milt, fur Bodenkunde, vol. i, p. 10. 



