AGRICULTURAL EXPERIMENTS 253 



of the drainage waters of some of the Rothamsted plots which 

 have been continuously receiving soluble compounds of phos- 

 phoric acid shows that the phosphoric acid is immediately 

 arrested and accumulates in the surface layers of the soil, where 

 indeed it remains in a condition continuously available for 

 the needs of the crop. Potash compounds, on the contrary, are 

 washed rather deeper into the soil and are not so thoroughly 

 arrested ; in both cases the absorption is so complete that the 

 farmer may apply these manures in the autumn and winter and 

 need not fear the loss of whatever is not taken up by the first 

 crop which occupies the land. 



Again, the existence in the laboratory of samples of soil 

 taken from the various plots on successive dates in their history 

 led to an investigation of the rate at which carbonate of lime — 

 that indispensable constituent of a fertile soil, is being removed 

 normally by rain and how far this rate is affected by different 

 systems of manuring. In the course of this investigation it 

 became evident that a great number of our cultivated soils owe 

 their present fertility to applications either of quicklime or 

 carbonate of lime that were made at regular intervals during 

 the seventeenth and eighteenth centuries; as this operation has 

 been very generally dispensed with during the last half-century 

 our soils must eventually become impoverished and fall to a 

 lower level of fertility. The lessons thus derived have begun to 

 bear fruit, first of all in the advice given to farmers all over the 

 country and then in the renewed attention that has been paid 

 to the regular use of lime that is everywhere apparent. Many 

 a farmer who is now seeing the benefits of applying lime to 

 his land does not realise that this is the outcome of a purely 

 scientific investigation at Rothamsted, which directed the 

 attention of his immediate advisers to a neglected side of 

 soil management. 



Whilst work upon the soil is likely to occupy the attention 

 at Rothamsted for many years to come and to cast light upon 

 many unsuspected difficulties, the crops themselves also provide 

 valuable material for investigation. The question of quality in 

 produce is particularly important to British farmers but is still 

 almost an unexplored field. We know in a general way that 

 particular soils produce crops of a higher quality and we can 

 sometimes roughly correlate this with manurial but more often 

 with physical factors of soil and climate. We do not, however, 



