266 MANUAL OF AGRICULTUEE. 



by Way and Krocker, says : — " It appears that about f of all the 

 rain which falls escapes through the drains, and the rest is got rid 

 of by evai)oration. An inch of rain falling on an imperial acre, 

 weighs rather more than a hundred tons ; hence, in the course of 

 a year, there must pass off' by the drains about 1000 tons of drain- 

 age water, carrying with it, out of the reach of the plants, such 

 substances as it has dissolved, and 1500 tons must remain to give 

 to the plant all that it holds in solution." (It has been already 

 stated, however, that the amount of moisture inhaled by the plants 

 covering an acre of ground alone exceeds the rainfall on such an 

 area.) These 1500 tons of water must, if they have the same 

 composition as that which escapes, contain only 2| lbs. of potash 

 and less than 1 lb. of ammonia. It may be alleged that the 

 water wliich remains, lying longer in contact with the soil, 

 may contain a large quantity of matter in solution, but even 

 admitting this to be the case, it cannot for a moment be 

 supposed that they can ever amount to more than a very 

 small fraction of what is required for a single crop. It may, 

 therefore, be stated with certainty that solubility in water 

 is not essential to the absorption of substances by the plant, 

 which must possess the power of itself directly attacking, acting 

 chemicallv on, and dissolving them. The mode in which it does 

 this is entirely unknown, but it, in all probability, depends upon 

 very feeble chemical action, and hence the importance of having 

 the soil constituents, not in solution, but in such a state that they 

 may be readily made soluble by the plants," viz., with the par- 

 ticles in a finely divided state. The nitrates being the most 

 soluble salts are washed out most abundantly, 



"We speak of soils as being stiff, tenacious and heavy, when 

 they are difficult to cultivate by means of the ordinary farm 

 power ; sharp and free when they are of a gritty texture, and 

 easily pulverised ; deaf, when of a spongy, inactive texture, as 

 w^hen the soil adheres to the iron of the plough and other imple- 

 ments ; deep, when they can be deeply furrowed and stirred 

 without the subsoil being reached ; thin, in the opposite case ; 

 retcjitive, when they retain the surface water, and admit only 

 of its slow percolation downwards ; and porous when the reverse 

 takes place. Such other terms are applied, as rich, poor, hungry, 

 grateful, kindly, and so on, according to the degree of natural 

 fertility in soils, the readiness with which they absorb and 

 retain manuriul matter added to them ; or, on the other hand, 

 with which they part with it unused, or their possession, or want 

 of other such like obvious properties. 



Black soils are to be seen in peaty, white soils in chalky dis- 

 tricts. Eed soils are frequent, and for the most part they are 

 very fertile. But the prevalent tint is a brownish one. Black, 

 dark-coloured soils reflect the solar rays less, and consequently 



