RATIONAL FRUIT CULTURE. 47 



the other hand, if there is nothing wrong with the cultural 

 conditions, such as the drainage, thin and scanty growth may 

 be regarded as a sure sign that they want something which they 

 cannot find in the ground. But what ? 



THE INGREDIENTS IN PLANT FOOD. 



There are three principal ingredients in plant-food — 

 phosphate, nitrate, and potash. All three occur in stable 

 manure, but as they are not in the right proportions, there 

 is necessarily some waste. For if a plant has consumed, say, 

 all the phosphate and all the nitrate, together with as much 

 of the potash as it needs to accompany them, and there is some 

 potash left over, the surplus cannot be used until more phos- 

 phate and nitrate are added. Hence the advantage of arti- 

 ficials. We can mix them with stable manure to supply any 

 deficiency, or, as, owing to the substitution of motors for 

 horses, it is becoming more and more difficult to procure and 

 more expensive, we can substitute them in the right propor- 

 tions for it. 



THE WASTAGE OF NITRATE. 



The most important of the three ingredients is the nitrate, 

 because whereas the other two remain in the soil, it dissolves 

 at once in water and quickly drains away into the lower strata 

 beyond the reach of the roots. This can be illustrated in a 

 simple way. If a plot containing plants of the same kind 

 is divided into three parts, and one part is treated with phos- 

 phate, another with nitrate, and the third with potash, the 

 plants on the nitrate-treated plot will almost certainly grow 

 more rapidly than the others, thus showing that they needed 

 nitrate more than either of the other two fertilisers. 



THE BACTERIA IN THE SOIL. 



It is true that Nature does something to make good the 

 wastage of nitrate which is perpetually going on. The ground 



