IV] MODERN METHODS 61 



number of trials are being made, and in some cases 

 on a definite systematic plan, to ascertain broadly the 

 needs of the commoner crops on important types of 

 soil. Chalk or lime is also applied, though, it must 

 be said, not always as often as necessary. 



2. Every effort is made to keep up the supply of 

 nitrogenous organic matter in the soil. It is not yet 

 possible, and perhaps never will be, to maintain the 

 same level as in land permanently covered with grass 

 or other vegetation. But leguminous crops are grown ; 

 the " seeds " (i.e. mixture of grass and clover) are left 

 for two or three years, in which time a dense root 

 mass forms; and in many instances a crop (such as 

 mustard, tares, etc.) is sown with the deliberate in- 

 tention of being ploughed into the ground. 



3. Enormous quantities of cattle food are im- 

 ported from newer countries and from less highly 

 developed regions. Only a small part — not more 

 than five or ten per cent. — of their nitrogen, phos- 

 phorus and potassium is retained by the animal : the 

 rest passes into the manure and goes to fertilise the 

 land. There are, however, very considerable losses 

 in making manure, and as much as one half of the 

 fertilising constituents may fail to reach the soil. 

 Greater economy is effected by feeding the animals 

 on the arable land, thus obviating the necessity for 

 making farmyard manure. 



4. Crops are therefore grown suitable for animals 



