14 FARMERS' BULLETIN 788. 



of the trees themselves. On the other hand, comp itition between 

 trees, where several rows are planted together, tends to make those 

 on the outside of the belt push their roots farther out into the open 

 ground. 



The width of the strip of ground to be allowed the windbreak 

 may be figured at from one and one-fourth to twice the height of 

 the trees; for instance, a single row of trees 50 feet high should be 

 allowed a strip of ground from 62 to 100 feet wide. 



DIRECT RETURNS FROM PLANTING. 



In addition to affording protection to crops and buildings, the 

 windbreak usually has considerable value as a source of wood supply 

 for use on the farm or for sale. In the f ollowing estimates of the tim- 

 ber value of various kinds of windbreaks the acreage on which the 

 figures are based includes not only the ground actually occupied by 

 the trees but also that which is shaded and sapped. The estimates are 

 for annual income per acre, discounted at the rate of 4 per cent from 

 the final value of the timber when cut. No allowance is made for 

 the cost of planting. 



Cottonwood rows and narrow belts planted on fairly moist bottom 

 lands yield an income of from $2.64 to $8.01 per acre, the greatest 

 values being obtained by cutting after the age of 40 years. Good re- 

 turns can not be expected from any but moist situations. 



Willow planted on thoroughly moist soil yields from $4.17 to $15.81 

 worth of posts per acre, the highest values being realized when cut- 

 ting is clone between the ages of 14 and 20 years. When utilized for 

 fuel, willow yields an income of from 72 cents to $2.78. 



Green ash yields from $2.53 to $6.51 in posts on the best class of 

 soils, and from $1.84 upward on poorer soils. It is an excellent 

 auxiliary to cottonwood, but will make good growth on much more 

 unfavorable situations. 



Honey locust is capable of growing on dry ground but grows very 

 rapidly where there is more moisture. On dry ground it produces 

 from $1 to $4.10 worth of posts per acre; on moist soil from $1.84 to 

 $5.42 per acre. When cut and allowed to make sprout growth it may 

 produce even larger yields. 



Osage orange may return as high as $12.51 per acre on the best 

 soils. Its value on second-class soils is from $3.94 to $11.85. Even 

 on third and fourth class soils it may return as much as $6 per acre. 

 Osage orange not only produces posts that are hardly exceeded in 

 lasting qualities by those obtained from any other species but is capa- 

 ble of growing on very dry situations. 



Russian mulberry planted in favorable situations usually produces 

 a number of rapid-growing shoots from each root, which makes it a 



