THE NUTRITION OF THE ROOT 67 



properties which would ensure a rapid decomposition of manure, 

 a process which is, however, retarded by the chief fault of this 

 soil, its great wetness. To counteract this, the soil must be 

 well drained, besides which, deep ploughing and repeated 

 harrowing, to cause an even breaking up of the soil, are very 

 beneficial. A large addition of straw-containing manure is 

 very paying, as it keeps up the porosity and permeability of 

 the soil. 



The chief means of improving the soil is, therefore, as we 

 have seen, the use of stable manure, the nutritive properties of 

 which we have already discussed. Besides these, it is proved 

 to be useful on account of its faculty of retaining water. It 

 can absorb its own, and sometimes even more than its own, 

 weight of water. Being very porous, it is true that it loses 

 this water very rapidly, but its great hygroscopic capacity 

 causes it to absorb the necessary amount of this indispensable 

 substance. Dry stable manure can absorb from the atmos- 

 phere and retain 40 per cent, of its weight of water, and this 

 absorption of water vapour takes place in greatest quantity 

 towards the morning, and thus from the absorption of dew the soil 

 obtains carbonic acid, ammonia, and nitrates, which are of con- 

 siderable benefit to the vegetation. Besides its own nutritive 

 value, stable manure has, as we see, the power of further enrich- 

 ing the soil from the atmosphere, and this fertilising power is 

 enhanced by the fact that stable-manure has a greater power 

 than any other substance of absorbing the heat of the sun and 

 the oxygen of the air. It accelerates, therefore, the pi'ocesses 

 of decomposition taking place in the soil, and thus brings 

 about and keeps up the conditions necessary for the active life 

 of the roots. 



Manuring with stable manure must therefore remain the 

 best method of improving the soil for every sort of cultivation, 

 while artificial manures may form useful additions. 



Where market-gardening is carried on on a very large scale, 

 so that occasionally there may be a lack of stable manure, it 

 will be found useful to plough in some crop before it has 

 matured its seeds. Leguminous plants, as, for instance, lupins, 

 are most useful for this purpose, as their power of forming 

 nitrogenous subtances from the nitrogen of the air will 



