44 THE CHEMISTRY OF THE FARM. 



potash, and phosphoric acid. When carted off the land 

 they are probably the most exhaustive crop that a farmer 

 can grow. As mangels have not the same difficulty that 

 turnips have of attacking the combined phosphoric acid of 

 the soil, phosphatic manures are, in their case, of much 

 less importance. Purely nitrogenous manures, as nitrate 

 of sodium, when applied alone to mangels, generally pro- 

 duce a great effect on the crop ; this is not the case with 

 turnips, which require phosphates as well as nitrogen in 

 their manure. 



As both turnips and mangels consume extremely large 

 amounts of plant food, a liberal general manuring with 

 farmyard manure is in most cases essential for the pro- 

 duction of a full crop ; but the special characteristic of 

 the manure for turnips should be phosphatic, and of that 

 for mangels nitrogenous. 



Potatos are surface feeders, and require a liberal general 

 manuring to ensure an abundant crop. 



As both^root crops and potatos require large supplies 

 of potash, kainit will be found of service on land naturally 

 poor in that ingredient. It will be chiefly required when 

 the crops are raised with artificial manures only, as farm- 

 yard manure will always supply a considerable amount of 

 potash. 



Forest Growth. — The figures given in the table repre- 

 sent the composition of the produce of beech, spruce 

 fir, and Scotch pine forests felled for timber, and are 

 the results of extensive investigations made in Ba- 

 varia. Nitrogen, sulphur, and chlorine determinations 

 are wanting. 



The amount of dry matter in the annual forest growth 



