50 



THE COMPOSITION OF FERTILE AND BARREN SOILS. 



without lime ; all must contain it if they can be in a condition 

 to produce good crops, for not one of our cultivated crops is des- 

 titute of lime ; without it they cannot grow ; hence it is that in 

 some soils a small dressing of lime produces a great effect. Lime 

 is the third principal constituent of soils. The fourth and last 

 principal constituent is organic matter arising from the remains 

 of former crops decaying roots and leaves. It is invariably 

 present in fertile soils ; but I would observe that the proportion 

 of organic matter does not determine the fertility of land. It 

 was assumed at one time that the fertility of soils was regulated 

 by the quantity of organic matter which they contained. If you 

 take up an agricultural work published as late as 1800, or even 

 1850 for I have found works of the kind as late as that you 

 will find a theory advocated that the more " humus " the soil 

 contains, the more fertile it is. But this theory is not correct. 



Vegetable Moulds. 

 ANALYSES OF FERTILE AND INFERTILE VEGETABLE MOULDS. 



No. 1 and 2 are fertile soils of a tract of land in North Holland, gained 



by embankment from the sea. 

 No. 3. Rich vegetable mould. 

 No. 4. Poor sandy mould. 

 No. 5. Very fertile peaty mould. 

 No. 6. Boggy ; very sterile land. 



