July 1, 1920 Universality of Field Heterogeneity 291 



Grouping all yields in two comparable subplots, we find 



1 91 3, first cutting, r= 0.407 ± 0.059, y/£',= 6.93. 



1913, second cutting, r= .343± .062, rlEf= 5.52. 



1 914, first cutting, r= .6o2± .045, y/£'y= 13.4. 

 1914, second cutting, r= .657± .040, r/Ej.= 16.4. 



We note that all the correlations are higher for a 2 -fold division than 

 for a 4-fold division. The coefficients for the second cutting of 191 3 are 

 again lower than the otner values. 



The foregoing results are based upon weightings of single cuttings 

 only. It is now desirable to determine the correlations for yield of 

 first and second cuttings combined. 



If the combined yield be considered in quarter plots as ultimate units 

 in 1 914 we find 



r==o.5i7±o.036, r/E^^ 14.2. 



Combining to obtain total yield in half plots in both 191 3 and 1914, we 

 have the following correlations between the yields of the two half plots: 

 For 1 91 3, r = 0.387 ±0.060, rlEj.= 6.46. 

 For 1914, r= .709± .035, r/Ej.= 20.2. 



5. — STRAW AND GRAIN IN WHEAT 



The data of the Rothamsted wheat plots,^ analyzed in an earlier paper 

 (5, p. 436-440, 443-444), show the following correlations when the 500 

 plots are grouped in 2 by 2 fold manner for the first 22 files and in a 2 

 by 3 fold manner for the twenty-third to the twenty-fifth file: 



For yield of grain, r=o.336±o.027, r/Ej.= i2.5. 



For yield of straw, r= .483^ .023, rlEr=20.g. 



6. STRAW AND GRAIN IN RAGI, ELEUSINE CORACANA 



Lehmann {12) has given a series of data derived from the yields of 

 grain and straw of ragi cultivated on the dry-land tract of the Experi- 

 mental Farm at Hebbel, near Bangalore, Mysore State. The plots used 

 were of i/io-acre area. 



The land was previously owned by several raiyats who have naturally treated it 

 somewhat differently in regard to manuring and cultivation. The various pieces 

 used as garden lands are of course in much better condition than those used for ordi- 

 nary dry crops. This causes considerable temporary differences to exist in some of 

 the plots in addition to probably slight permanent differences. {12, 6th Rpt., p. 2.) 



. From these conditions one would expect a high degree of heteroge- 

 neity in the series of plots. The data permit the testing of the possibility 

 of a decrease in heterogeneity due to uniformity of crop and treatment 

 for three years. 



' For data see Mercer and Hall {15, p. iiq); also Map B of Harris (5). 



