130 MAINE STATE COLLEGE. 



An examination of table A shows that the set of plots which 

 has been cultivated for six years without manure has yielded the 

 present year 38.9 bushels of oats. 



The following three sets of plots have each received during the 

 six years three applications of what is called a complete fertilizer, 

 that is, a fertilizer containing phosphoric acid, potash aud nitro- 

 gen. The only difference in the treatment of the three sets of 

 plots being that the source of phosphoric acid in the first set was 

 dissolved bone black, in the second fine ground bone, and in the 

 third fine ground South Carolina rock. This year's crop shows 

 but little difference between the effectiveness of the phosphoric 

 acid from dissolved bone black and fine ground bone. It should 

 be remembered, however, that this crop was grown two years 

 after the last application of the fertilizers and the soluble phos- 

 phoric acid of the dissolved bone black had, without doubt, 

 reverted. 



Little can be said in regard to the crop produced with South 

 Carolina rock as a source of phosphoric acid. These plots gave 

 a crop which was no greater than that obtained on the unmanured 

 plots, and was less than was obtained on plots manured with 

 muriate of potash and sulphate of ammonia with no South Caro- 

 lina rock. 



No explanation is known for this variation in the crop of the 

 South Carolina rock plots, from what might have been expected. 



The product on the plots manured with commercial fertilizers 

 was unsatisfactory, considering the treatment they had received 

 in the way of fertilizers. 



Table C furnishes the data for studying the effect of the phos- 

 phoric acid from different sources through the six years since the 

 experiment was commenced. Dissolved bone black gives the 

 largest total yield of oats, the second largest yield of peas and 

 the smallest yield of hay. Fine ground bone has given the 

 largest yield of hay and peas and the second largest yield of oats. 

 The South Carolina rock is second in yield of hay and third in 



yield of oats and peas. 



The plots manured with commercial fertilizers gave large yields 



the first year of the experiment, two sets even exceeding the 

 yield of the stable manure plots. The second year of the experi- 

 ment the weather was unfavorable and the yield on all plots was 

 light. The stable manure has, however, with the exception of that 

 year, given uniformly good crops, while those upon which commer- 

 cial fertilizers were used have not produced what could be called a 



