197 



mittently, as when they pass through spaces of soils free from phos- 

 phates. Again, these micro-organisms, regarded now as essential to 

 soil fertility, and which specially favour fermentations, and which con- 

 vert inert plant food into assimilable forms, can prosper only when phos- 

 phates everywhere abound. Besides superphosphates are exceedingly 

 beneficial to young crops, in hastening them beyond the period when 

 they are most susceptible to the attack of parasitical insects. 



Potassic manures are so readily fixed by the double silicates in loams 

 and clays that it is almost impossible to secure their proper dissemina- 

 tion through a soil. They are, therefore, as a rule, not to be recommended 

 as a top dressing. Properly speaking, they should be applied some 

 time before the crop is planted, so that by repeated ploughing and har- 

 rowing, they may become well mixed with the soil However, salts of 

 potash have different diffusive powers in themselves, which are greatly 

 modified by admixture with other manures. Henc^^, the refinement of 

 fertilisation would require that in compounding commercial manures, 

 that form of potash should be used which would be increased in diffu- 

 sive power by the presence of the forms of nitrogen and phosphoric 

 acid used. 



AT WHAT TIME SHOULD FERTILISERS BE APPLIED ? 



From what has been said, it is evident that the separate application 

 of each ingredient of commercial fertilisers at such a time and in such 

 quantity as the characteristics of the individual soil and crop would 

 suggest, would be the most scientific course of procedure. 



Potassic manures could properly be applied several months before 

 planting a crop. Super or acid phosphates a little before or at the time 

 of planting, while nitrogen should be furnished only to meet the de- 

 mands of the growing plants, and then only in such quantities as will 

 supply immediate nectssities. The above are the suggestions of science, 

 but unfortunately, in our present stage of advancement, they cannot be 

 rigidly followed. The larger part of the supply of our commercial fer- 

 tilisers are manipulated goods containing two or more ingredients, and 

 therefore separate applications cannot be followed.(3) 



DEPTH AT WHICH FERTIIISERS SHOULD BE PLACED. 



As already seen, potassic fertilisers should never be applied on the 

 surface of growing crops, since fixation would occur there and the root- 

 lets of plants never find it. It has been found that the more these fer- 

 tilisers are diffused through the soil the better the results obtained. 

 Depths of two to ten inches is the range of cane roots in an average 

 clay soil. Therefore, an application at four to five inches, to be subse- 



(3) It is quite within the power of planters to purchase the potassic, pkosphatio 

 and nitrogenous constituents of fertilisers separately and to apply them at such 

 timet as experience shows to be most suitable. Potash and phosphates may b» ap- 

 plied during the period of preparing the land for plant canes, or, ia the case of 

 ratoons, soon after the plant canes have been cut. In this way they become well 

 incorporated with the soil by the operations of tillage and weeding before groat 

 root development takes place. The nitrogenous fertilisers can be applied t > the 

 growing crop at a later period in small quantities, as top dressings at such times 

 as the crop appears to demand an application of assimilated nitrogen, a condition 

 which, in the case of the sugar cane, the experienced planter has little difficulty in 

 recognizing. 



