ARTIFICIAL MANURES AND HORTICULTURAL PRACTICE. 51 



to make these develop rapidly and vigorously in order that they 

 may recover as soon as possible from the ravages made upon 

 them by insects, frosts, and bad weather ; further, that they 

 may elaborate as quickly as possible a widely distributed and 

 deeply penetrating network of healthy roots, and in this way 

 acquire so much vital energy and so much power of resistance 

 that they can encounter with successful opposition all injurious 

 attacks, from whatever source. 



In order to attain all this, the following condition must be 

 fulfilled — that the plant during its early stages of development 

 has placed at its disposal as much easily available and readily 

 soluble phosphoric acid as it can possibly assimilate. 



Basic Slag is a somewhat new phosphatic manure, containing 

 from 14 to 20 per cent, of phosphoric acid, or equal from 30 to 

 42 per cent, of tricalcium phosphate. One ton weight will con- 

 tain about 336 lbs. of phosphoric acid and 1,120 lbs. of lime ; the 

 latter will be of a caustic character, and will act on the nitrogen 

 of the soil probably more quickly than the lime in superphosphate. 

 The phosphoric acid in basic slag acts slower and over a longer 

 period than the same element in superphosphate. It is a suitable 

 material for providing the soil with a lasting supply of phosphoric 

 acid, especially in the lower layers of soil, such as vine-borders; 

 this manure will also ensure the healthy development of fruit 

 trees, vines, ornamental trees, and shrubs. It also provides a 

 good dressing for lawns, cricket grounds, and paddocks, as it 

 encourages the growth of clovers and the finer quality of 

 grasses. 



Basic slag may be used in preference to superphosphate on 

 all wet, peaty, and rich garden soils, on account of it contain- 

 ing free caustic lime which neutralises the organic acids of the 

 soil. But it must not be used in combination with ammonia 

 salts, because it sets the ammonia free and causes a loss of plant- 

 food. 



Potash Manures. — Four kinds of potash manures are enumer- 

 ated in Table V. — kainit, sulphate of potash, muriate of potash, 

 and phosphate of potash. Kainit is a crude potash salt, and the 

 commonest form in which potash is now employed as manure. 

 One ton will contain about 515 lbs. of potash, with about 25 per 

 cent, of magnesia salts, and 35 per cent, of common salt 

 (chloride of sodium). 



