RURAL ECONOMICS 



1835 



Table VIII. — Relative efficiency of ammonia nitrogen and nitrate nitrogen 

 as ivorked out by G^egoire. 



These results, which have been confirmed by other authorities, show 

 that the probable error decreases as the size of the plot increases, but not 

 proportionately so that in practice it is usual to adopt unit areas not larger 

 than 100 sq. metres, for with bigger plots, it becomes increasingly difficult 

 to find a suitable experimental area where tlie soil shows no variability. 

 3) The appropriate size of samples for analysis. Rodewald has 

 shown : a) that for seed samples, 300 to 400 seeds are rec^uired for piirity 

 and germination tests, the error diminishing rapidly up to this point and 

 but very slowly above it ; and that the " error of tolerance " to be adopted 

 is 2.22 per cent for ,^eeds with a purity and germination capacity of 05 per 

 cent. He also confirms Noble's conclusions (i) which were based on the 

 results of practical experiments. 



vSummarising, the writer points out that the study of agricultural eco- 

 nomics is a method of investigation which only yields approximate results as 

 it is not always possible to isolate the required factors. The method, 

 however, is the most logical one for obtaining a knowledge of the empirical 

 laws governing the management of farms provided the data are collected 

 with care and submitted to searching criticism. 



131 7 - Farm Cost Accounting in the United States in riw Breedcr\ Gazette, voi. lxx, 



Xo 13, p. 553, Chicago, .September 27, 1916, 



A wave of interest in farm cost accounting has been started by county 

 agricultural agents in the United States. Some farm accounting has been 

 done by the Minnesota and Illinois universities, from actual detailed annual 

 farm records, showing the possibilities of a system of finding the cost of 



(i) C. GiNi. La regolaritei dei fenomini rari, Giornalc dc^li Economisti, March 1908, 

 pp. 210-291. 



