THE ORANGE IN CALIFORNIA— FERTILIZATION. 149 



Potash Fertilizers.— In fertilizing the orange, potash is most 

 frequently used either in the form of the sulphate or of wood 

 ashes. While sulphate of potash has been most widely used, 

 there is apparently little evidence that it is superior to other 

 forms. Muriate of potash, containing the equivalent of about 

 fifty per cent of actual potash, the form probably most used 

 in the apple and peach orchards of the North, has been little 

 used in orange groves. Apparently those who have used this 

 form have obtained uniformly good results. Kainit, or German 

 potash salt, which is a crude double salt of magnesium sulphate 

 with calcium chloride, containing the equivalent of from twelve 

 to fourteen per cent of actual potash, is a form much used in 

 Northern orchards and is promising for use in orange groves. 

 Its very active effect in increasing the surface tension of the 

 soil moisture, and thus attracting water to the trees, might 

 make it an excellent form to add in early spring to aid the 

 plant in withstanding the spring drought, which is so frequently 

 injurious to the orange tree and sometimes fatal to the fruit 

 crop. Growers not supplied with facilities for irrigation would, 

 undoubtedly, find it profitable to consider carefully points of 

 this nature in fertilization. The noticeable effect of potash on 

 the orange tree appears to be its aid in completing and matur- 

 ing the wood. Apparently an insufficient amount of potash is 

 shown by an excessive growth of weak, immature wood, which 

 does not harden up as winter approaches and is liable to be 

 injured by frost. 



An abundance of potash, in the form of sulphate of potash 

 or tobacco stems, is said by many growers to produce excess- 

 ively sour fruit. That potash is very necessary in fruit 

 production is shown by the fact that the fruit contains a large 

 percentage of this element. An average of fifteen analyses of 

 different varieties of Florida oranges shows 52.05 per cent to 

 be about the usual amount of potash in the ash of the orange 

 fruit. The ash in these fifteen analyses averaged 0.916 per 

 cent, or less than one per cent of the total weight of the fruit. 



Phosphoric ^cifi.— Phosphoric acid, which is a very necessary 

 element of fertilization on Florida orange lands, is mostly used 

 in the form of dissolved bone black, acidulated bone or phos- 

 phate rock, soft phosphate, raw bone, guano, etc. The immedi- 

 ate effect of phosphoric acid on the orange tree and fruit is 

 little understood. Several intelligent growers claim to be able 



