32 



BULLETIN 933, U. S. DEPARTMENT OF AGRICULTURE. 



for this prevailing inferiority of walnut plantations — either there 

 was a poor choice of planting sites or there was wrong management 

 of the planted stands, or both. 



Table 13. — Diameter growth in plantations, in comparison with average and 

 slow growth in natural stands. 



Age 



(years). 



Diameter, breast high (inches). 



In plan- 

 tations. 



In natural stands — 



Of aver- 

 age 

 growth. 



Of slow 

 growth . 



10 

 20 

 30 

 40 

 50 

 60 

 70 

 80 



2.0 



5.2 



7.4 



9.2 



10.9 



12.3 



13.4 



14.4 



1.2 

 5.0 



8.8 

 12.5 

 15.7 

 18.3 

 20.6 

 22.2 



0.6 

 3.1 

 5.4 

 8.0 

 10.8 

 12.9 

 15.2 

 17,2 



CHOICE OF PLANTING SITES. 



The plantations of walnut in the prairie regions were quite natu- 

 rally started in the situations in which the owners most needed trees ; 

 that is, on the treeless uplands or, occasionally, in recent years, on 

 parts of cleared bottom lands. The sites selected were only rarely 

 those which supported tree growth at the time of the settlement. 

 The soil quality of these sites may be excellent, but the moisture 

 present in the soil during the summer is insufficient for the flourish- 

 ing growth of walnut. 



As has been pointed out on pages 4 and 18, walnut needs for good 

 growth a deep, fertile soil, both well watered and well drained, per- 

 mitting the free movement of soil moisture and, at the same time, the 

 access of air to the roots. These qualities are the more necessary the 

 less favorable the climatic conditions, especially the precipitation. 

 From Indiana westward soils suitable for planting are to be found 

 principally in bottom lands, but bottom-land soils are in fact to be pre- 

 ferred even in the East. Swampy areas and places where cottonwood, 

 willows, sycamore, or river birch form, or have formed, the chief 

 growth will usually prove unsuited to walnut, though areas subject 

 to floods for short periods, in which the backwater does not stand 

 long in the depression, may form excellent sites. If the soil is a 

 sterile sand, or if hardpan exists not far beneath the surface, as in 

 parts of the Lake States, walnut can not be grown satisfactorily, 

 even in the most favorable climate. 



In the East, with its larger amount and better distribution of rain- 

 fall, much more freedom in the selection of planting sites is possible 

 than in the prairie regions or in the Lake States. In the limestone 

 regions of Tennessee, Kentucky, West Virginia, and the northeastern 

 part of the range in general, cut-over lands and even rocky hillsides, 



