SCIENCE IS ITS APPLICATION. 85 



farming, the great desideratum was to make a soil rich 

 in plant food, that could be called upon to grow any 

 crop suitable to the climate ; of late years, in this coun- 

 try, the tendency has been to fertilize especially for the 

 crop under cultivation. One system is fertilizing the 

 land, the other is fertilizing the crop. With tobacco, 

 and in fact with all market garden crops, fertilizing the 

 soil is the method to he followed, except that for tobacco 

 an excess of phosphoric acid is unnecessary, and also 

 that special care must be taken to exclude all compounds 

 of chlorine. 



This system of stocking the land with an excess of 

 manurial matter is the more essential for tobacco, be- 

 cause lands are very differently affected by the fertilizing 

 elements. Some lands have a great power of fixing and 

 retaining potash in an almost insoluble form ; others 

 have a strong affinity for lime ; and much difference is 

 noticed in the ease with which the nitrogen supply is 

 developed for the use of the growing crop. The only 

 safe rule is to give a superabundance of all forms of 

 plant food that are required. More care is necessary in 

 the selection of manurial supply for tobacco than for 

 any other crop, because it is a remarkably delicate plant, 

 and the texture and burning qualities of the leaf are 

 largely influenced by the materials upon which it feeds. 



Another reason why tobacco and many other quick- 

 growing crops require much larger stores of plant food 

 in the soil than is found in the chemical analyses of the 

 product, is because the roots of the crop cannot occupy 

 every portion of the soil, especially in the early stages of 

 growth. The demand made on the soil, or on fertili- 

 zers, by the tobacco crop, is greater than that made by 

 any other crops which receive as much of nearly every 

 kind of plant food. Hay is almost as exhaustive as 

 tobacco, measured in total extract from the soil, but 

 grass grows the whole year throughout, save when the 



