with thin skin, and little rag. Sulphate of ammonia has the 

 effect, growers testify, of sweetening the fruit to a considerable 

 extent. There seems to be little doubt as to the correctness of 

 this view, but why it is so, remains a question. The sweetening 

 is probably more marked if there is a slight deficiency of 

 potash, The use of very large quantities of either sulphate of 

 ammonia or nitrate of soda may result disastrously, acting as 

 " chemical poison," killing the trees outright 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 sea- 

 coast, in soil saturated with the salty sea water, are, in some 

 respects, under almost the same condition as in the deserts, 

 having great difficulty in obtaining sufficient water, though 

 surrounded by water. The root hairs have difficulty in extract- 

 ing the water from the salty solutions. The 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 to prevent the transpiration of the water which 

 cannot be replenished by further absorption. Sulphate of am- 

 monia has been very widely used among orange growers. 

 Nitrate of soda has been but little used thus far, but is ap- 

 parently growing in favour. Its insecticide and water-attracting 

 properties are probably much greater than those of sulphate of 

 ammonia. 



Potash Fertilisers, 



In fertilising 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 ap- 

 parently 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 probably 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 

 uniformly obtained good results. Kainit, or German potash 

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

 calcium chloride, containing the equivalent of 12 to l4 per cent, 

 of actual potash, is a form much used in ISTorthern 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 w^ithstanding the 



