Mar. lo, 1919 Organic Matter and Water-Holding Capacity of Soil 265 



grown upon it every year without the use of clover or manure. In 1883 

 the university acquired the farm for experimental purposes and the next 

 year the field was seeded to clover, from that time on being kept in a 

 good rotation until in 1893 Snyder {11, p. 2) laid it out in six plots as a 

 fertility experiment (fig. i, A). All available records indicate that the 

 land included in the plots had been treated alike during the preceding 

 36-year period (i 856-1 892). Plots 2 and 3 were to be kept in 4- and 

 5-year rotations, including clover and receiving manure, and each of the 

 others to be devoted continuously to the same grain crop and to receive 



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 O - f<"' ComposiUs A 



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Fig. I. — Diagram showing arrangement of plots and crops on field J, University Farm, St. Paul, Minn, 

 A is the original plan adhered to from 1893 to 1914, while B shows the cropping plan in 1915, C shows 

 the arrangement of the samples taken for the two composites from a plot. 



neither manure nor fertilizer, No. i, 4, 5, and 6 being planted to wheat, 

 com, oats, and barley, respectively. The construction of a bam in 191 2 

 upon part of plot i has rendered this useless for experimental purposes 



(PI. 36). 



The present discussion deals chiefly with plots 3 and 4, on the latter 

 of which, beginning with 1893, there had been grown 22 successive crops 

 of corn, without the application of any manure. On the other there had 

 been only 6 crops of com, but 4 of barley, 7 of oats, and 5 of clover, 

 while 25 tons per acre of manure had been applied, 5 tons with each crop 

 of com except that of 1897. 



