GROWING THE PLANTS 65 



soil may modify the validity of calculations of this 

 sort, since soils differ so much. 



One factor in soil -fertility is not supplied by chemi- 

 cals. That factor is humus, a more important one 

 than the others. In this stable -manure has the advan- 

 tage, but the same results may be obtained by the 

 judicious use of green -crops before planting and of 

 cover -crops afterward. 



PROPAGATION 



There is practically but one way of propagating 

 black -caps, and that is by means of tips. Plants can 

 be grown from root cuttings or by burying the entire 

 cane and cutting it in pieces after roots are thrown 

 out, but these methods are so seldom used that there 

 is little need of taking them into consideration. These 

 tips take root naturally, unaided, in sod ground, for 

 they thread their way amongst the grass roots, and 

 are thus held in place until established. In culti- 

 vated ground they are blown about by the wind, and 

 do not have an opportunity of becoming fastened in 

 the soil. It is necessary, therefore, to put the tips 

 down and cover them, in order to secure any consider- 

 able number of plants. This may be done with a hoe, 

 spade or any other convenient tool. It is better to 

 point the tip well downward, so that the end is the 

 deepest part when covered. This will produce a plant 

 of much better shape than if the tip is put in nearly 

 horizontal and covered for a considerable length. 



A tool hung somewhat like an adze, but with a 



