297 



in an ordinary damp manure shed will sometimes be found 

 standing in a pool of liquid, a solution formed by the water 

 which the contents have absorbed from the atmosphere. Such 

 an explanation of the wetness of soil dressed with nitrate of 

 soda is entirely inadequate, because the extra quantity of water 

 retained by the soil from such a cause would be imperceptible. 

 Suppose as much as a ton of nitrate of soda per acre was 

 applied, that it absorbed its own weight of water, and again 

 remained wholly in the surface layer of the land 9 inches 

 deep, the water retained by the whole ton of nitrate of soda 

 would not amount to more than one in a thousand of soil, and 

 could not cause the slightest difference to the texture. More- 

 over, determinations have been made of the water actually 

 present in the Rothamsted soils on the mangold plots, and 

 no differences that could affect the behaviour of the soil have 

 ever been detected. The altered appearance and the greater 

 apparent wetness must therefore be due to some other cause. 

 Mechanical analyses were next made of the soils. It seemed 

 possible that the greater stickiness of the nitrated soils might 

 be due to a general disintegration of the soil into finer particles, 

 brought about by the long-continued action of the fertiliser. 

 But it was surprising to find that the nitrated soils were 

 distinctly and regularly coarser, that is to say, they had been 



TABLE XCIX. Mechanical Analyses of Rothamsted Soils, with and 

 without Sodium Nitrate. 



deprived of some of their finer particles. Table XCIX. gives the 

 average mechanical analyses of five pairs of plots from the 



