53 



right and causing them to throw off their leaves. Here again the exact 

 action is not, to my knowledge, understood. The following may be the 

 explanation : It is well known that plants growing on the soa-coast, in 

 soil saturated with the salty sea water, are, in some respects, under 

 almost the same conditions as in deserts, having great difficulty in 

 obtaining sufficient water, though surrounded by water. The root hairs 

 have difficulty in extracting the water from the strong salty solutions. 

 Tho plants thus have various devices to prevent excessive evaporation 

 or transpiration of water from the leaves, similar to those developed by 

 desert plants. The injurious effect of the nitrogen salts may in this 

 case be caused by simply producing such a strong solution of the salt 

 in the vicinity of the plant that the roots are not able to absorb the 

 necessary moisture, and thus the plant is compelled to cut off its leaves 

 t© prevent the transpiration of the water which can not be replenished 

 by further absorption. 



Sulphate of ammonia has been very widely used among orange grow- 

 ers. Nitrate of soda has been but little used thus far, but is apparently 

 growing in favour. Its insecticide and water- attracting properties are 

 probably much greater than those of sulphate of ammonia. 



POTASH FERTILISERS. 



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, thei*e is apparently little evidence that it is in 

 any way superior, to other forms Muriate of potash, containing the 

 equivalent of about 50 per cent of actual potash, the form pi'obably 

 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 Oerman potash salt, 

 which is a crude double salt of magnesium sulphate with calcium chlo- 

 ride, containing the equivalent of from 12 to 14 per cent of actual po- 

 tash, is a form much used in Northern orchards and is promising for use 

 in orange groves. Its very active effect in increasing the surface ten- 

 sion 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 sametimes fatal to the fruit crop. Growers not sup- 

 plied with facilities for irrigation would, undoubtedly find it profit- 

 able to consider carefully points of this nature in fertilisation. The 

 noticeable effect of potash on the orange tree appears to be its aid 

 in completing and maturing 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 excessively 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 . 916 per cent, 

 or less than 1 per cent of the total weight of the fruit. 



