PLANTING AND CARE OF TREES , ll5 



the soil. In farm practice it is a common thing to grow a crop 

 of clover, rye, or buckwheat for the purpose of ploughing under. 



The water-holding capacity of a soil is dependent largely upon 

 its humus content. Trees growing in soil that is well supplied with 

 humus are not likely to suffer from drought during dry seasons. 

 It is not necessary here to enumerate the many other functions 

 of humus in the soil, but it is enough to say that it should be 

 supplied whenever practicable. 



Fertilizers for Trees — Most soils contain a sufficient supply of 

 the various elements of plant food — nitrogen, potash, and 

 phosphoric acid — and when the soil is in a good mechanical con- 

 dition the tree is able to obtain without difficulty these elements, 

 and it is seldom necessary to make additional applications. But 

 since the soil where our shade trees are supposed to grow is not 

 usually in a suitable mechanical condition and since it is often 

 impracticable to improve it in this respect* the application of 

 chemical fertilizers often proves beneficial. 



Inasmuch as soils differ so widely with regard to their manurial 

 requirements, it is always difficult to make an}' general recommen- 

 dations. The following formula is suggested as an annual dressing 

 for each full grown tree. A very large tree should receive a 

 slightly heavier dressing and a smaller one proportionately less : — 

 Nitrate of soda (157c nitrogen or its equivalent) G pounds 



Muriate or sulphate of potash (50% potash) 6 " 



Acid phosphate (187^ phosphoric acid) 8 " 



This is a light dressing and may be greatly increased without 

 fear or injury. The three compounds may be mixed together and 

 scattered over the surface of the ground, extending considerably 

 beyond the spread of the branches. The application should be 

 made in the spring, just as the leaves are appearing, and during 

 a heavy rain, or just before watering the ground from a hose. 

 If these directions are followed and if the lumps are well mashed 

 there will be no injury to the grass. The practice of spreading 

 stable manure on the ground beneath the trees in the fall and in 

 raking it off in the spring, is a connnendable one, but many 

 people object to it on account of the odor and appearance. 



Cultivation — Whenever it is feasible, the ground beneath and 

 around the trees should be cultivated. Cultivation aeriates the 

 soil and increases chemical action, making more plant food avail- 



