he can lend his money. Hence the above rates will be used in calculations. 



(d) Length of Time Between Planting and Harvest. This in- 

 fluences the amount to which the interest charges on the various items 

 will accumulate. In previous calculations the writer has found the best 

 available evidence seems to indicate about 60 years as giving the highest 

 profits from the use of the soil for private forestry, while 80 to 100 years 

 is more profitable for government forestry. In order to make a comparison 

 as favorable as possible to private forestry, 60 years is chosen for the 

 length of rotation. Specific costs are figured on this basis using the 

 various interest rates already named. 



Influence of Yield Per Acre on Costs Per Thousand Board Feet. 

 Except for the interest on the soil value and the taxes with interest there- 

 on., the foregoing elements of cost per acre will not vary widely on dif- 

 ferent qualities of soil. It is, of course, common knowledge that the yield 

 on different soil qualities will vary greatly. This variation is even greater 

 than generally supposed. The United States Forest Service has made a 

 careful study of this subject in Western Washington and Oregon, the 

 results of which have unfortunately only in part been published. In this 

 study measurements were taken of stands on a wide variety of soils 

 which were classified into three qualities on the basis of the yields found. 

 Quality I or first quality 44 M. per acre, Quality II or medium quality 32 

 M. feet per acre and Quality III or poorest quality 16% M. feet per acre 

 for the same period. Obviously, then, if the cost per acre of growing the 

 timber remains little changed for the different qualities the cost per 1,000 

 feet B. M. will be much less in the case of large yields, just as would be 

 the case in an agricultural crop. These results are brought out in tables 

 about to follow, in which the yields shown by the U. S. Forest Service 

 study are used as authoritative. 



Results of Foregoing Elements Presented in Tabular Form. The 

 definite results of the foregoing elements have been worked out mathe- 

 matically for each item and are presented in the following tables in order 

 to show their relationships, and make comparisons of different interest 

 rates and tax systems as simple as possible. The itemized and total costs 

 to owners working under different interest rates are presented in a single 

 table for each of the soil qualities already mentioned. Costs on Quality 

 I soil are presented in Table I, on Quality II soil in Table III, and on 

 Quality III soil in Table V. The intervening tables present summaries 

 of those mentioned in which the first costs, the interest charges and the 

 iax costs are segregated and their percentage relations to each other 

 computed. 



On Quality II forest soil the costs per acre are reduced slightly 

 owing to lesser soil value, and hence to less taxes due to the lower soil 

 value and the smaller volume of stand of timber. The land is considered 

 worth $5.00 and the taxes to be two-thirds of what they were on Quality 

 I. The yield according to yield tables prepared by the U. S. Forest 

 Service will be 32,000 ft. B. M. per acre at 60 years*. The costs will be 

 as shown for different owners in Table I. 



Comparing Table III with Table I, it is seen that where interest 

 rates are low, costs per acre are not reduced much below Quality I, but 

 as yield is less the most cost per M. is raised, except in the case of 6 per 

 cent and 7 per cent interest rates. Where interest is high, reduction in land 



