FERTILIZERS AND FERTILIZING. . 3QJ 



Sources of PotaslL The forms in which potash may 

 be supplied to citrus trees are: high-grade potash, con 

 taining about 51 per cent, available potash; low-grade 

 sulphate of potash, containing about 26 per cent.; and 

 muriate of potash, containing about 50 per cent. The 

 raw salt, kainit, is also used sometimes, but the bulk per 

 unit of potash is so great that it is too expensive to be 

 recommended. 



Of all the materials used, the sulphates are the saf- 

 est and best. It is well established that it is not well to 

 use muriate of potash on some crops. Their quality is 

 impaired thereby. This is true of tobacco, the Irish po- 

 tato, the sugar beet and perhaps other crops. The deteri- 

 oration is ascribed to the presence of chlorine, which inter- 

 feres with the accumulation of starch as a stored product. 

 There is a general impression abroad that muriate of 

 potash is not a good substance to use on orange trees, 

 and while its deleterious effects have never been properly 

 elucidated, the impression is probably well grounded. It 

 may be that chlorine interferes with sugar formation 

 and we know that starch and sugar are very closely re- 

 lated compounds, fruit sugar being C 6 H 12 O 6 ; starch, 

 C 6 H 10 5 . 



High-grade sulphate of potash is usually preferable^* 

 to low-grade, as the cost of freight and handling is less 

 per unit of potash, but either may be used. 



Sources of Nitrogen. Nitrogen may be obtained as 

 nitrate of soda, sulphate of ammonia, dried blood, cot- 

 tonseed meal and castor pomace. Tankage, generally 

 sold in the markets as blood and bone, is also another 

 source of supply. Nitrate of soda contains approxi- 

 mately 16 per cent, nitrogen ; sulphate of ammonia, 21 per 

 cent. ; dried blood, 14 per cent. ; cottonseed meal, 6.5 per 



