142 ANNUAL. REPORT OF THE Ufl. i>ui;. 



The most extended and systematic experiments along this line, 

 however, had been conducted at the Maryland and I'enusylvania Sta- 

 tions. Bulletin No. 68, of the Maryland Experiment Station gives 

 a detailed report of the former. A summary of the principal facts 

 relating to this experiment may also be found in Bulletin No. 94, of 

 the Pennsylvania Department of Agriculture. The average total re- 

 sults show that insoluble phosphoric acid yields a greater number 

 of pounds of both grain and straw than phosphates in the soluble 

 and reverted form, and the yield was not only greater but the cost 

 was only about one-half as much. The experiments in Pennsylvania 

 were planned by Dr. W. H. Jordan, now Director of the Experiment 

 Station at Geneva, N. Y., and a full discussion of the results cover- 

 ing a period of 12 years during^which the experiment was in progress 

 may be found in the station report for 1895. The soil is a limestone 

 clay formed from the decomposition of the surrounding and under- 

 lying rock which is largely magnesian limestone. It has the general 

 appearance of a clayey loam. In the beginning of the experiment 

 a given weight of each of the different fertilizers was applied, the 

 plan being to apply the same amount of phosphoric acid in the four 

 different forms, but as the composition varied considerably, a chemi- 

 cal analysis was made in the later years of the experiment and a 

 definite amount of the valuable ingredients applied per acre. The 

 rotation used was the one common to this section, wheat, grass, corn 

 and oats. The plots were 1-20 of an acre in area and the results are 

 stated in terms of so much per acre^ all of the plots, except of course 

 the nothing plot, received an application of potash and nitrogen at 

 the rate of 200 lbs. of muriate of potash and 240 lbs. sulphate of 

 ammonia per acre; these amounts corresponding to 100 lbs. of actual 

 potash and 47 lbs. of nitrogen per acre. The various forms of phos- 

 phoric acid were supplied as follows: Soluble, from dissolved bone 

 black, reverted from dissolved bone black, treated 12 hours previous 

 to using, with an equal weight of quick lime; insoluble phosphoric 

 acid from ground bone and South Carolina rock. The bone black 

 in both cases being supplied at the rate of 200 lbs. per acre, or 32 

 lbs. of phosphoric acid and the ground bone and South Carolina rock 

 at the rate of 150 lbs. to the acre, corresponding to 40 lbs. of phos- 

 phoric acid. The following table shows the average yield of wheat, 

 grass, corn and oats through the entire period of 12 years during 

 which the experiment was in progress: 



