THE USE OF MANURES 165 



Where a crop is top-dressed little can be 

 done to incorporate the manure with the 

 soil, but under other circumstances it is a 

 good plan to work the manure into the land by 

 means of the harrow or cultivator. The 

 passage of these implements tends to improve 

 the lateral distribution, and, at the same 

 time, results in the manure being more com- 

 pletely mixed up with the mass of soil. 

 This helps the soil to fix it, and at the same 

 time it is more completely appropriated by 

 plant roots. The relationship between soil 

 and manure should also be carefully con- 

 sidered. Thus, other things being equal, 

 sulphate of ammonia is preferable to nitrate 

 of soda on light land. Basic slag has an 

 advantage over superphosphate in the case 

 of peaty soil, whereas the reverse may be 

 the case of chalky land. Potash, again, will 

 have relatively more influence where the 

 soil is sand or peat, than where it is clay. 



Enough has probably been said to empha- 

 size the desirability of considering the rela- 

 tionship of manures to crops. In the case 

 of barley, for instance, which is a shallow- 

 feeding plant, sulphate of ammonia is rela- 

 tively of more importance than nitrate of 

 soda, whereas in the case of mangolds the 

 reverse holds true. In the treatment of 



