38 WINDBREAKS. 



Beyond this there was a sudden increase in the size and number of the 

 plants, which were, for a short distance out, larger than the normal 

 for the field. The total loss was 146.3 per cent of the possible yield 

 on a strip as wide as the height of the tree. If there is deducted from 

 this the 51.5 per cent lost in cornfields, where there is damage only 

 from shading, the 95 per cent left represents the sapping damage of 

 soft maple roots extending to the north. 



A similar effect was found in the case of alfalfa east of an osage 

 orange hedge (see diagram 14). No rain fell during the month in 

 which this (the second) crop matured, and at its end the dearth of 

 moisture in the root zone was quite marked. In this case the sapping 

 damage was 20 per cent in addition to the normal effects of shading 

 on the east side of osage hedges. 



The season was too moist to furnish examples of the most severe 

 damage from sapping. It is safe to say, however, that in cases of 

 extreme drought, the loss of annual crops may be complete to the 

 outer limits of the tree roots. 



REMEDIES. 



Damaging competition for moisture between forest trees and 

 smaller forms of vegetation may be greatly lessened in any of the 

 following ways: 



(1) By thorough cultivation of the soil adjacent to the trees, 

 increasing the moisture of the lower soil, and decreasing the necessity 

 for wide root extension on the part of the trees. With rows and 

 hedges along roads a strip between the trees and the road should be 

 cultivated in order to induce root growth on that side. 



(2) By very deep plowing each year alongside of shallow-rooted 

 species, such as osage orange and mulberry, in order to cut off the 

 surface roots. 



(3) By deep plowing or even dynamiting of the subsoil in extreme 

 cases, before planting 'the trees, to encourage deep rooting, and to 

 facilitate the upward capillary movement of moisture. 



(4) By the use of seed crops, such as timothy and other grasses, 

 clover, and alfalfa, next to the trees. This should not be done until 

 the trees have attained the height desired for, protective purposes, 

 since the competition of these crops will in a large measure check the 

 growth of the trees. 



(5) By planting tap-rooted species like white pine, Norway pine, 

 oaks, hickories, and maples on the edge of the grove or belt adjacent 

 to crops. 



III. SOIL FERTILITY. 



Farmers often lay much stress upon the fact that the trees in a 

 windbreak seem to sap the fertility of the soil along their borders. 

 Careful studies of the requirements of various forest trees have shown 



