THE MONTHLY BULLETIN. 417 



California tends to show that about 50 trees to the acre is the maximum 

 that can profitably be used; where the soil is rich and deep and large 

 growing varieties are planted, this number should be diminished. 



The form of planting — that is the arrangement of the trees with re- 

 gard to each other and the direction of the rows — is of importance. On 

 land which is level or of uniform grade there are two suitable arrange- 

 ments in use — the square and the diamond systems. In the square 

 system the trees are planted equi-distant, in rows at right angles to each 

 other. Each tree then has soil and air space equal to the square of the 

 distance apart. Thus if the trees are planted 30 feet apart each tree 

 will occupy an area of 900 square feet, which represents a fraction of 

 over 48 trees to the acre. In the diamond system the land is laid out in 

 a series of equilateral triangles in rows which are at an angle of 60 

 degrees to each other. The area apportioned to each tree will be equal 



^ M^- 



f. ?. 



■ / 



Fig. SS. — The Columella olive. (State 

 Hort. Com.) 



to two equilateral triangles wlicse sides are the distance apart of the 

 trees. Distances of 32J feet apart will give the same number of trees 

 per acre by the diamond system as 30 feet apart by the square. In 

 determining the direction of the rows, the main consideration is to so 

 place them that the trees will get the maximum exposure to the sun 

 and the best distribution of the sunlight. On hilly or rolling land the 

 degree of insolation is influenced principally by the direction of the 

 slope and can be modified very slightly by the planting plan. Where 

 the slopes are considerable, the planting in rows following the contour 

 lines is often advisable, as this simplifies irrigation, cultivation, hauling 

 of crops and fertilization. 



Selection of Trees in the Nursery. — Most orchard trees succeed best 

 if planted when quite small. The olive tree is an exception to this rule. 

 It may be transplanted at almost any time. A very small tree requires 

 more constant care during the first two years. A large tree, on the 



