34 BULLETIlSr 699, U. S. DEPARTMENT OF AGRICULTTJIIE. 



prior to 1913, in which j^ear the results reported were obtained, the 

 field was cropped with a 6-3^ear rotation, including 1 year each of 

 corn, oats (or cowpeas), and wheat, and 3 years of meadow and 

 pasture with clover and timothy. 



The figures obtained seem very favorable to the use of heavy appli- 

 cations (2 tons) of raw rock phosphate, but they are the yields of 

 only one year. A comparison of the yields obtained therefore with 

 and without the addition of raw rock phosphate is probably justified^ 

 although the land treated with phosphate rock received twice as 

 much limestone as the plot on which no phosphate was applied. It 

 is possible that the additional amount of lime which this tract received 

 had considerable influence on the large increase in yield. 



In the fall of 1913 Hoplrins, Hosier, Pettit, and Fisher^ reported 

 m detail nine-year results of an experiment begun at Galesburg, 111., 

 in 1904. The soil of this experiment field is the brown silt loam 

 prairie soil of the Upper Illinois glaciation. The field was divided 

 into three series of plots, each series containing 20 plots of one-fifth 

 acre each. A six-year rotation was followed. The previous history 

 of the experiment field is not given. 



At the beginning of the experiment limestone was applied to the 

 first 15 plots of each series at the rate of 1,300 pounds per acre, and 

 again to tie same plots in either 1912 or 1913 at the rate of 4 tons per 

 acre. In 1904 the first applications of raw ground rock phosphate 

 were made, but the regular plan of this experiment which was to 

 apply 1^ tons per acre of raw ground phosphate rock every six years 

 before plowing for corn was not fully underway on all series of 

 plots until 1906. One hundred pounds of potassium sulphate per 

 acre was applied annually. 



It was planned to study the use of phosphate rock, both in grain 

 farming and live-stock farming. In the grain-farming system crop 

 residues are returned to the various plots in proportion to the pro- 

 duction of each and in the live-stock system all produce (or its equiva- 

 lent) is used for feed and bedding and the manure returned to the 

 plots in proportion to their yields during the preceding rotation. 

 In this particular experiment, however, these two systems were not 

 in operation on all series until 1911 and 1912. The average yields 

 of the various crops during the nine years of the experiment are given 

 in Table XI. 



» 111. Agr. Expt. Sta., SoU Kept. No. 7 (1913). 



