growing site, (specifically, some needle colors matched 5 GY 5/6 and 5 GY 5/8 

 in the Munsell chart) they appeared to be vigorous and typical of commercial 

 quality Christmas trees. 



Two out of every three such trees may be expected to fall within the one 

 standard deviation range in Table 11 (or 21 out of 22 within two times the 

 deviation presented). 



This indicates considerable variability in healthy trees in any one nutrient 

 characteristic rather than a rigidity, and also suggests a lack of rigidity in nutrient 

 demand. 



Despite this flexibility in healthy trees it is hoped that in any one instance 

 the preliminary standards will prove of value in the use of foliar analysis to 

 pinpoint nutrient deficiency. 



IV. Appendix 



A. Bulk density 



Bulk density (referred to in Table 4 and the studies) is also called volume 

 weight, or apparent specific gravity. It is the ratio between the dry weight of a 

 given volume of undisturbed soil and the weight of an equal volume of water. 

 The volume measured includes pore space. (Note-specific gravity itself is a 

 similar ratio but pore space is not included). Very compact soils have high 

 volume weights (less pore space contributes to this). Mineral soil material free 

 of organic matter develops very little variation in specific gravity, therefore the 

 amount of organic matter in the soil is reflected in lowered bulk density. Gen- 

 erally, rocks and sand in soil favor high values (Lutz and Chandler, Forest Soils, 

 John Wiley & Sons Inc., 1946). 



B. Tree Grade for the Main Plots 



Christmas tree grading measures appeal-looks. The overall appeal of a particu- 

 lar tree is determined by varying combinations of many minute characteristics 

 which are not obvious at first glance. These characteristics are grouped into 

 three classes, major features: 



1. Crown Symmetry 



a. Even length of branches at a particular node. 



b. Branches of proportional length at successive nodes. 



c. Full whorls (branches evenly spaced around the bole at each node). 



d. Stemform (straight, bent, crooked, multi-leaders, etc.) 



2. Crown Density 



a. Branches per node 



b. Internodal length 



c. Internodal branching 



d. Foliage characteristics (number and length of needles). 



28 



