44 BULLETIN' 699, U. S. DEPARTMENT OF AGRICULTURE. 



but none of these were conducted for a period of more than four 

 3^ears, so the results are not considered in detail. 



All the other experiments with raw rock phosphate conducted by 

 the Indiana station are described and discussed by Wiancko and 

 Conner^ in a recent bulletin entitled "Acid Phosphate versus Raw 

 Eock Phosphate as Fertilizer." 



Two of these experiments, one at Littles, in Pike County, and 

 the other at Scottsburg, Scott County, were begun at the same time 

 (1905), and are similar in every respect. There are three series of 

 plots of one-twentieth acre each, and a three-year rotation of corn, 

 wheat, and clover has been practiced, so that each crop could be 

 grown on one series every year. " When the clover failed cowpeas or 

 soy beans were substituted. The land was plowed once in three years 

 for corn, except when clover failed, when it was also plowed for 

 soy beans or cowpeas. The wheat was drilled on disked corn stubble 

 and the clover seeded on the wheat in the spring." The various fer- 

 tilizers were all applied to the wheat in the first round of the rotation, 

 the treatment being as follows: Manure at the rate of 10 tons per 

 acre, raw rock at the rate of 1 ton per acre, and acid phosphate drilled 

 with the wheat at the rate of 130 pounds per acre. After the first 

 rotation paanure was again applied at the same rate on every corn 

 crop and acid phosphate on every wheat crop. A second ton of 

 raw rock phosphate was applied for corn and cowpeas in 1911 and 

 1912. Both fields were limed in 1911 at the rate of 2 tons of finely 

 ground limestone per acre. While there were three check plots in 

 each of the three series, the various fertilizer materials were repre- 

 sented by only one plot in each series. 



The field at Littles is nearly level with a slight slope running 

 lengthwise of the plots. The soil is described as a yellowish brown 

 silt loam of medium fertility. The phosphoric acid content as de- 

 termined by analysis is 0.13 per cent. 



The Scottsburg field is almost level on one series, but rises grad- 

 ually through the two other series of plots. The soil is Volusia silt 

 loam and is considered of low fertility. The total phosphoric acid 

 content as determined by analysis is less than 0.1 per cent. The 

 average yields of the three crops on both fields during the 10 years 

 of the experiment are given in Tables XX and XXL 



» Ind. Agr. Expt. Sta., Bull. No. 187, vol. 18 pp. 1055-1082 (1916). 



