42 THE POTATO. 



the drills. Superphosphate should be applied at planting 

 time, applying as advised for the sulphate of potash. 

 Nitrate of soda and sulphate of ammonia are best used as 

 top-dressings when the shaws are a few inches high. 



Lime. There is no doubt that lime is an excellent 

 material to apply to land about to be cropped with pota- 

 toes. It is a valuable substance for mechanically improv- 

 ing the condition of soils. Mechanically it renders clay 

 soil more pliable and less plastic, and, in the case of light 

 soils, helps to bind the particles together, and thus render 

 them less susceptible to drought. Chemically, lime 

 sweetens sour soils, such as those of a peaty nature, or 

 that have been heavily manured generation after genera- 

 tion. Moreover, it unlocks the inert fertility of a soil, and 

 sets free potash for the food of the crops. Further, it acts 

 upon vegetable acids and liberates ammonia, encourages 

 the formation of nitrates in the soil, and generally forms an 

 excellent plant food. Then again, lime in its caustic con- 

 dition destroys the various insect and fungoid pests in the 

 soil, and is, therefore, of great value all round. Lime is 

 best applied in its caustic or " quick " form to heavy clay 

 and sour soils, and in the form of fine chalk to light soils. 

 As it quickly sinks in the soil it should be applied in small 

 doses at frequent intervals, rather, than large doses at long 

 intervals. Quicklime may be applied in winter or early 

 spring, at the rate of one to two tons per acre ; and chalk 

 at the rate of three to five tons per acre in winter. The 

 former dose should be repeated every five or six years, and 

 the latter every eight or nine years. Quicklime should be 

 slaked and immediately ploughed or harrowed in, not left 

 on the surface of the soil, otherwise its caustic properties 

 and chemical and mechanical value will be lost, or 

 weakened. 



Seaweed. This is an excellent manure for potatoes 

 where it can be easily and cheaply obtained. It contains 

 from four to twenty per cent, of potash, and about three 



